sql_class.h

/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights
   reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef SQL_CLASS_INCLUDED
#define SQL_CLASS_INCLUDED

/* Classes in mysql */

#include "my_global.h"                          /* NO_EMBEDDED_ACCESS_CHECKS */
#ifdef MYSQL_SERVER
#include "unireg.h"                    // REQUIRED: for other includes
#endif
#include "sql_const.h"
#include <mysql/plugin_audit.h>
#include "log.h"
#include "rpl_tblmap.h"
#include "mdl.h"
#include "sql_locale.h"                         /* my_locale_st */
#include "sql_profile.h"                   /* PROFILING */
#include "scheduler.h"                     /* thd_scheduler */
#include "protocol.h"             /* Protocol_text, Protocol_binary */
#include "violite.h"              /* vio_is_connected */
#include "thr_lock.h"             /* thr_lock_type, THR_LOCK_DATA,
                                     THR_LOCK_INFO */
#include "opt_trace_context.h"    /* Opt_trace_context */
#include "rpl_gtid.h"

#include "sql_digest_stream.h"            // sql_digest_state

#include <mysql/psi/mysql_stage.h>
#include <mysql/psi/mysql_statement.h>
#include <mysql/psi/mysql_idle.h>
#include <mysql_com_server.h>
#include "sql_data_change.h"
#include "my_atomic.h"

#define FLAGSTR(V,F) ((V)&(F)?#F" ":"")

extern "C"
const char *set_thd_proc_info(void *thd_arg, const char *info,
                              const char *calling_func,
                              const char *calling_file,
                              const unsigned int calling_line);

#define thd_proc_info(thd, msg) \
  set_thd_proc_info(thd, msg, __func__, __FILE__, __LINE__)

extern "C"
void set_thd_stage_info(void *thd,
                        const PSI_stage_info *new_stage,
                        PSI_stage_info *old_stage,
                        const char *calling_func,
                        const char *calling_file,
                        const unsigned int calling_line);
                        
#define THD_STAGE_INFO(thd, stage) \
  (thd)->enter_stage(& stage, NULL, __func__, __FILE__, __LINE__)

class Reprepare_observer;
class Relay_log_info;

class Query_log_event;
class Load_log_event;
class sp_rcontext;
class sp_cache;
class Parser_state;
class Rows_log_event;
class Sroutine_hash_entry;
class User_level_lock;
class user_var_entry;

enum enum_ha_read_modes { RFIRST, RNEXT, RPREV, RLAST, RKEY, RNEXT_SAME };

enum enum_delay_key_write { DELAY_KEY_WRITE_NONE, DELAY_KEY_WRITE_ON,
                            DELAY_KEY_WRITE_ALL };
enum enum_slave_exec_mode { SLAVE_EXEC_MODE_STRICT,
                            SLAVE_EXEC_MODE_IDEMPOTENT,
                            SLAVE_EXEC_MODE_LAST_BIT };
enum enum_slave_type_conversions { SLAVE_TYPE_CONVERSIONS_ALL_LOSSY,
                                   SLAVE_TYPE_CONVERSIONS_ALL_NON_LOSSY,
                                   SLAVE_TYPE_CONVERSIONS_ALL_UNSIGNED,
                                   SLAVE_TYPE_CONVERSIONS_ALL_SIGNED};
enum enum_slave_rows_search_algorithms { SLAVE_ROWS_TABLE_SCAN = (1U << 0),
                                         SLAVE_ROWS_INDEX_SCAN = (1U << 1),
                                         SLAVE_ROWS_HASH_SCAN  = (1U << 2)};

enum enum_mark_columns
{ MARK_COLUMNS_NONE, MARK_COLUMNS_READ, MARK_COLUMNS_WRITE};
enum enum_filetype { FILETYPE_CSV, FILETYPE_XML };

/* Bits for different SQL modes modes (including ANSI mode) */
#define MODE_REAL_AS_FLOAT              1
#define MODE_PIPES_AS_CONCAT            2
#define MODE_ANSI_QUOTES                4
#define MODE_IGNORE_SPACE               8
#define MODE_NOT_USED                   16
#define MODE_ONLY_FULL_GROUP_BY         32
#define MODE_NO_UNSIGNED_SUBTRACTION    64
#define MODE_NO_DIR_IN_CREATE           128
#define MODE_POSTGRESQL                 256
#define MODE_ORACLE                     512
#define MODE_MSSQL                      1024
#define MODE_DB2                        2048
#define MODE_MAXDB                      4096
#define MODE_NO_KEY_OPTIONS             8192
#define MODE_NO_TABLE_OPTIONS           16384
#define MODE_NO_FIELD_OPTIONS           32768
#define MODE_MYSQL323                   65536L
#define MODE_MYSQL40                    (MODE_MYSQL323*2)
#define MODE_ANSI                       (MODE_MYSQL40*2)
#define MODE_NO_AUTO_VALUE_ON_ZERO      (MODE_ANSI*2)
#define MODE_NO_BACKSLASH_ESCAPES       (MODE_NO_AUTO_VALUE_ON_ZERO*2)
#define MODE_STRICT_TRANS_TABLES        (MODE_NO_BACKSLASH_ESCAPES*2)
#define MODE_STRICT_ALL_TABLES          (MODE_STRICT_TRANS_TABLES*2)
#define MODE_NO_ZERO_IN_DATE            (MODE_STRICT_ALL_TABLES*2)
#define MODE_NO_ZERO_DATE               (MODE_NO_ZERO_IN_DATE*2)
#define MODE_INVALID_DATES              (MODE_NO_ZERO_DATE*2)
#define MODE_ERROR_FOR_DIVISION_BY_ZERO (MODE_INVALID_DATES*2)
#define MODE_TRADITIONAL                (MODE_ERROR_FOR_DIVISION_BY_ZERO*2)
#define MODE_NO_AUTO_CREATE_USER        (MODE_TRADITIONAL*2)
#define MODE_HIGH_NOT_PRECEDENCE        (MODE_NO_AUTO_CREATE_USER*2)
#define MODE_NO_ENGINE_SUBSTITUTION     (MODE_HIGH_NOT_PRECEDENCE*2)
#define MODE_PAD_CHAR_TO_FULL_LENGTH    (ULL(1) << 31)

extern char internal_table_name[2];
extern char empty_c_string[1];
extern LEX_STRING EMPTY_STR;
extern LEX_STRING NULL_STR;
extern MYSQL_PLUGIN_IMPORT const char **errmesg;

extern bool volatile shutdown_in_progress;

extern "C" LEX_STRING * thd_query_string (MYSQL_THD thd);
extern "C" char **thd_query(MYSQL_THD thd);

class CSET_STRING
{
private:
  LEX_STRING string;
  const CHARSET_INFO *cs;
public:
  CSET_STRING() : cs(&my_charset_bin)
  {
    string.str= NULL;
    string.length= 0;
  }
  CSET_STRING(char *str_arg, size_t length_arg, const CHARSET_INFO *cs_arg) :
  cs(cs_arg)
  {
    DBUG_ASSERT(cs_arg != NULL);
    string.str= str_arg;
    string.length= length_arg;
  }

  inline char *str() const { return string.str; }
  inline size_t length() const { return string.length; }
  const CHARSET_INFO *charset() const { return cs; }

  friend LEX_STRING * thd_query_string (MYSQL_THD thd);
  friend char **thd_query(MYSQL_THD thd);
};


#define TC_LOG_PAGE_SIZE   8192
#define TC_LOG_MIN_SIZE    (3*TC_LOG_PAGE_SIZE)

#define TC_HEURISTIC_RECOVER_COMMIT   1
#define TC_HEURISTIC_RECOVER_ROLLBACK 2
extern ulong tc_heuristic_recover;

typedef struct st_user_var_events
{
  user_var_entry *user_var_event;
  char *value;
  ulong length;
  Item_result type;
  uint charset_number;
  bool unsigned_flag;
} BINLOG_USER_VAR_EVENT;


class Key_part_spec :public Sql_alloc {
public:
  LEX_STRING field_name;
  uint length;
  Key_part_spec(const LEX_STRING &name, uint len)
    : field_name(name), length(len)
  {}
  Key_part_spec(const char *name, const size_t name_len, uint len)
    : length(len)
  { field_name.str= (char *)name; field_name.length= name_len; }
  bool operator==(const Key_part_spec& other) const;
  Key_part_spec *clone(MEM_ROOT *mem_root) const
  { return new (mem_root) Key_part_spec(*this); }
};


class Alter_drop :public Sql_alloc {
public:
  enum drop_type {KEY, COLUMN, FOREIGN_KEY };
  const char *name;
  enum drop_type type;
  Alter_drop(enum drop_type par_type,const char *par_name)
    :name(par_name), type(par_type)
  {
    DBUG_ASSERT(par_name != NULL);
  }
  Alter_drop *clone(MEM_ROOT *mem_root) const
    { return new (mem_root) Alter_drop(*this); }
};


class Alter_column :public Sql_alloc {
public:
  const char *name;
  Item *def;
  Alter_column(const char *par_name,Item *literal)
    :name(par_name), def(literal) {}
  Alter_column *clone(MEM_ROOT *mem_root) const
    { return new (mem_root) Alter_column(*this); }
};


class Key :public Sql_alloc {
public:
  enum Keytype { PRIMARY, UNIQUE, MULTIPLE, FULLTEXT, SPATIAL, FOREIGN_KEY};
  enum Keytype type;
  KEY_CREATE_INFO key_create_info;
  List<Key_part_spec> columns;
  LEX_STRING name;
  bool generated;

  Key(enum Keytype type_par, const LEX_STRING &name_arg,
      KEY_CREATE_INFO *key_info_arg,
      bool generated_arg, List<Key_part_spec> &cols)
    :type(type_par), key_create_info(*key_info_arg), columns(cols),
    name(name_arg), generated(generated_arg)
  {}
  Key(enum Keytype type_par, const char *name_arg, size_t name_len_arg,
      KEY_CREATE_INFO *key_info_arg, bool generated_arg,
      List<Key_part_spec> &cols)
    :type(type_par), key_create_info(*key_info_arg), columns(cols),
    generated(generated_arg)
  {
    name.str= (char *)name_arg;
    name.length= name_len_arg;
  }
  Key(const Key &rhs, MEM_ROOT *mem_root);
  virtual ~Key() {}
  /* Equality comparison of keys (ignoring name) */
  friend bool foreign_key_prefix(Key *a, Key *b);
  virtual Key *clone(MEM_ROOT *mem_root) const
    { return new (mem_root) Key(*this, mem_root); }
};

class Table_ident;

class Foreign_key: public Key {
public:
  enum fk_match_opt { FK_MATCH_UNDEF, FK_MATCH_FULL,
                      FK_MATCH_PARTIAL, FK_MATCH_SIMPLE};
  enum fk_option { FK_OPTION_UNDEF, FK_OPTION_RESTRICT, FK_OPTION_CASCADE,
                   FK_OPTION_SET_NULL, FK_OPTION_NO_ACTION, FK_OPTION_DEFAULT};

  LEX_STRING ref_db;
  LEX_STRING ref_table;
  List<Key_part_spec> ref_columns;
  uint delete_opt, update_opt, match_opt;
  Foreign_key(const LEX_STRING &name_arg, List<Key_part_spec> &cols,
              const LEX_STRING &ref_db_arg, const LEX_STRING &ref_table_arg,
              List<Key_part_spec> &ref_cols,
              uint delete_opt_arg, uint update_opt_arg, uint match_opt_arg)
    :Key(FOREIGN_KEY, name_arg, &default_key_create_info, 0, cols),
    ref_db(ref_db_arg), ref_table(ref_table_arg), ref_columns(ref_cols),
    delete_opt(delete_opt_arg), update_opt(update_opt_arg),
    match_opt(match_opt_arg)
  {
    // We don't check for duplicate FKs.
    key_create_info.check_for_duplicate_indexes= false;
  }
  Foreign_key(const Foreign_key &rhs, MEM_ROOT *mem_root);
  virtual Key *clone(MEM_ROOT *mem_root) const
  { return new (mem_root) Foreign_key(*this, mem_root); }
};

typedef struct st_mysql_lock
{
  TABLE **table;
  uint table_count,lock_count;
  THR_LOCK_DATA **locks;
} MYSQL_LOCK;


class LEX_COLUMN : public Sql_alloc
{
public:
  String column;
  uint rights;
  LEX_COLUMN (const String& x,const  uint& y ): column (x),rights (y) {}
};

class MY_LOCALE;

struct Query_cache_block;

struct Query_cache_tls
{
  /*
    'first_query_block' should be accessed only via query cache
    functions and methods to maintain proper locking.
  */
  Query_cache_block *first_query_block;
  void set_first_query_block(Query_cache_block *first_query_block_arg)
  {
    first_query_block= first_query_block_arg;
  }

  Query_cache_tls() :first_query_block(NULL) {}
};

/* SIGNAL / RESIGNAL / GET DIAGNOSTICS */

typedef enum enum_diag_condition_item_name
{
  /*
    Conditions that can be set by the user (SIGNAL/RESIGNAL),
    and by the server implementation.
  */

  DIAG_CLASS_ORIGIN= 0,
  FIRST_DIAG_SET_PROPERTY= DIAG_CLASS_ORIGIN,
  DIAG_SUBCLASS_ORIGIN= 1,
  DIAG_CONSTRAINT_CATALOG= 2,
  DIAG_CONSTRAINT_SCHEMA= 3,
  DIAG_CONSTRAINT_NAME= 4,
  DIAG_CATALOG_NAME= 5,
  DIAG_SCHEMA_NAME= 6,
  DIAG_TABLE_NAME= 7,
  DIAG_COLUMN_NAME= 8,
  DIAG_CURSOR_NAME= 9,
  DIAG_MESSAGE_TEXT= 10,
  DIAG_MYSQL_ERRNO= 11,
  LAST_DIAG_SET_PROPERTY= DIAG_MYSQL_ERRNO
} Diag_condition_item_name;

extern const LEX_STRING Diag_condition_item_names[];

#include "sql_lex.h"                            /* Must be here */

extern LEX_CSTRING sql_statement_names[(uint) SQLCOM_END + 1];
class Delayed_insert;
class select_result;
class Time_zone;

#define THD_SENTRY_MAGIC 0xfeedd1ff
#define THD_SENTRY_GONE  0xdeadbeef

#define THD_CHECK_SENTRY(thd) DBUG_ASSERT(thd->dbug_sentry == THD_SENTRY_MAGIC)

typedef ulonglong sql_mode_t;

typedef struct system_variables
{
  /*
    How dynamically allocated system variables are handled:
    
    The global_system_variables and max_system_variables are "authoritative"
    They both should have the same 'version' and 'size'.
    When attempting to access a dynamic variable, if the session version
    is out of date, then the session version is updated and realloced if
    neccessary and bytes copied from global to make up for missing data.
  */ 
  ulong dynamic_variables_version;
  char* dynamic_variables_ptr;
  uint dynamic_variables_head;    /* largest valid variable offset */
  uint dynamic_variables_size;    /* how many bytes are in use */
  LIST *dynamic_variables_allocs; /* memory hunks for PLUGIN_VAR_MEMALLOC */
  
  ulonglong max_heap_table_size;
  ulonglong tmp_table_size;
  ulonglong long_query_time;
  my_bool end_markers_in_json;
  /* A bitmap for switching optimizations on/off */
  ulonglong optimizer_switch;
  ulonglong optimizer_trace; 
  ulonglong optimizer_trace_features; 
  long      optimizer_trace_offset;
  long      optimizer_trace_limit;
  ulong     optimizer_trace_max_mem_size;
  sql_mode_t sql_mode; 
  ulonglong option_bits; 
  ha_rows select_limit;
  ha_rows max_join_size;
  ulong auto_increment_increment, auto_increment_offset;
  ulong bulk_insert_buff_size;
  uint  eq_range_index_dive_limit;
  ulong join_buff_size;
  ulong lock_wait_timeout;
  ulong max_allowed_packet;
  ulong max_error_count;
  ulong max_length_for_sort_data;
  ulong max_sort_length;
  ulong max_tmp_tables;
  ulong max_insert_delayed_threads;
  ulong min_examined_row_limit;
  ulong multi_range_count;
  ulong myisam_repair_threads;
  ulong myisam_sort_buff_size;
  ulong myisam_stats_method;
  ulong net_buffer_length;
  ulong net_interactive_timeout;
  ulong net_read_timeout;
  ulong net_retry_count;
  ulong net_wait_timeout;
  ulong net_write_timeout;
  ulong optimizer_prune_level;
  ulong optimizer_search_depth;
  ulong preload_buff_size;
  ulong profiling_history_size;
  ulong read_buff_size;
  ulong read_rnd_buff_size;
  ulong div_precincrement;
  ulong sortbuff_size;
  ulong max_sp_recursion_depth;
  ulong default_week_format;
  ulong max_seeks_for_key;
  ulong range_alloc_block_size;
  ulong query_alloc_block_size;
  ulong query_prealloc_size;
  ulong trans_alloc_block_size;
  ulong trans_prealloc_size;
  ulong group_concat_max_len;

  ulong binlog_format; 
  my_bool binlog_direct_non_trans_update;
  ulong binlog_row_image; 
  my_bool sql_log_bin;
  ulong completion_type;
  ulong query_cache_type;
  ulong tx_isolation;
  ulong updatable_views_with_limit;
  uint max_user_connections;
  ulong my_aes_mode;

  my_thread_id pseudo_thread_id;
  my_bool tx_read_only;
  my_bool low_priority_updates;
  my_bool new_mode;
  my_bool query_cache_wlock_invalidate;
  my_bool engine_condition_pushdown;
  my_bool keep_files_on_create;

  my_bool old_alter_table;
  uint old_passwords;
  my_bool big_tables;

  plugin_ref table_plugin;
  plugin_ref temp_table_plugin;

  /* Only charset part of these variables is sensible */
  const CHARSET_INFO *character_set_filesystem;
  const CHARSET_INFO *character_set_client;
  const CHARSET_INFO *character_set_results;

  /* Both charset and collation parts of these variables are important */
  const CHARSET_INFO  *collation_server;
  const CHARSET_INFO  *collation_database;
  const CHARSET_INFO  *collation_connection;

  /* Error messages */
  MY_LOCALE *lc_messages;
  /* Locale Support */
  MY_LOCALE *lc_time_names;

  Time_zone *time_zone;
  /*
    TIMESTAMP fields are by default created with DEFAULT clauses
    implicitly without users request. This flag when set, disables
    implicit default values and expect users to provide explicit
    default clause. i.e., when set columns are defined as NULL,
    instead of NOT NULL by default.
  */
  my_bool explicit_defaults_for_timestamp;

  my_bool sysdate_is_now;
  my_bool binlog_rows_query_log_events;

  double long_query_time_double;

  my_bool pseudo_slave_mode;

  Gtid_specification gtid_next;
  Gtid_set_or_null gtid_next_list;
  my_bool show_old_temporals;
} SV;


typedef struct system_status_var
{
  ulonglong created_tmp_disk_tables;
  ulonglong created_tmp_tables;
  ulonglong ha_commit_count;
  ulonglong ha_delete_count;
  ulonglong ha_read_first_count;
  ulonglong ha_read_last_count;
  ulonglong ha_read_key_count;
  ulonglong ha_read_next_count;
  ulonglong ha_read_prev_count;
  ulonglong ha_read_rnd_count;
  ulonglong ha_read_rnd_next_count;
  /*
    This number doesn't include calls to the default implementation and
    calls made by range access. The intent is to count only calls made by
    BatchedKeyAccess.
  */
  ulonglong ha_multi_range_read_init_count;
  ulonglong ha_rollback_count;
  ulonglong ha_update_count;
  ulonglong ha_write_count;
  ulonglong ha_prepare_count;
  ulonglong ha_discover_count;
  ulonglong ha_savepoint_count;
  ulonglong ha_savepoint_rollback_count;
  ulonglong ha_external_lock_count;
  ulonglong opened_tables;
  ulonglong opened_shares;
  ulonglong table_open_cache_hits;
  ulonglong table_open_cache_misses;
  ulonglong table_open_cache_overflows;
  ulonglong select_full_join_count;
  ulonglong select_full_range_join_count;
  ulonglong select_range_count;
  ulonglong select_range_check_count;
  ulonglong select_scan_count;
  ulonglong long_query_count;
  ulonglong filesort_merge_passes;
  ulonglong filesort_range_count;
  ulonglong filesort_rows;
  ulonglong filesort_scan_count;
  /* Prepared statements and binary protocol */
  ulonglong com_stmt_prepare;
  ulonglong com_stmt_reprepare;
  ulonglong com_stmt_execute;
  ulonglong com_stmt_send_long_data;
  ulonglong com_stmt_fetch;
  ulonglong com_stmt_reset;
  ulonglong com_stmt_close;

  ulonglong bytes_received;
  ulonglong bytes_sent;
  /*
    Number of statements sent from the client
  */
  ulonglong questions;

  ulong com_other;
  ulong com_stat[(uint) SQLCOM_END];

  /*
    IMPORTANT!
    SEE last_system_status_var DEFINITION BELOW.
    Below 'last_system_status_var' are all variables that cannot be handled
    automatically by add_to_status()/add_diff_to_status().
  */
  double last_query_cost;
  ulonglong last_query_partial_plans;
} STATUS_VAR;

/*
  This is used for 'SHOW STATUS'. It must be updated to the last ulong
  variable in system_status_var which is makes sens to add to the global
  counter
*/

#define last_system_status_var questions


inline CHARSET_INFO *
mysqld_collation_get_by_name(const char *name,
                             CHARSET_INFO *name_cs= system_charset_info)
{
  CHARSET_INFO *cs;
  MY_CHARSET_LOADER loader;
  my_charset_loader_init_mysys(&loader);
  if (!(cs= my_collation_get_by_name(&loader, name, MYF(0))))
  {
    ErrConvString err(name, name_cs);
    my_error(ER_UNKNOWN_COLLATION, MYF(0), err.ptr());
    if (loader.error[0])
      push_warning_printf(current_thd,
                          Sql_condition::WARN_LEVEL_WARN,
                          ER_UNKNOWN_COLLATION, "%s", loader.error);
  }
  return cs;
}


#ifdef MYSQL_SERVER

void free_tmp_table(THD *thd, TABLE *entry);


/* The following macro is to make init of Query_arena simpler */
#ifndef DBUG_OFF
#define INIT_ARENA_DBUG_INFO is_backup_arena= 0; is_reprepared= FALSE;
#else
#define INIT_ARENA_DBUG_INFO
#endif

class Query_arena
{
public:
  /*
    List of items created in the parser for this query. Every item puts
    itself to the list on creation (see Item::Item() for details))
  */
  Item *free_list;
  MEM_ROOT *mem_root;                   // Pointer to current memroot
#ifndef DBUG_OFF
  bool is_backup_arena; /* True if this arena is used for backup. */
  bool is_reprepared;
#endif
  /*
    The states relfects three diffrent life cycles for three
    different types of statements:
    Prepared statement: STMT_INITIALIZED -> STMT_PREPARED -> STMT_EXECUTED.
    Stored procedure:   STMT_INITIALIZED_FOR_SP -> STMT_EXECUTED.
    Other statements:   STMT_CONVENTIONAL_EXECUTION never changes.
  */
  enum enum_state
  {
    STMT_INITIALIZED= 0, STMT_INITIALIZED_FOR_SP= 1, STMT_PREPARED= 2,
    STMT_CONVENTIONAL_EXECUTION= 3, STMT_EXECUTED= 4, STMT_ERROR= -1
  };

  enum_state state;

  /* We build without RTTI, so dynamic_cast can't be used. */
  enum Type
  {
    STATEMENT, PREPARED_STATEMENT, STORED_PROCEDURE
  };

  Query_arena(MEM_ROOT *mem_root_arg, enum enum_state state_arg) :
    free_list(0), mem_root(mem_root_arg), state(state_arg)
  { INIT_ARENA_DBUG_INFO; }
  /*
    This constructor is used only when Query_arena is created as
    backup storage for another instance of Query_arena.
  */
  Query_arena() { INIT_ARENA_DBUG_INFO; }

  virtual Type type() const;
  virtual ~Query_arena() {};

  inline bool is_stmt_prepare() const { return state == STMT_INITIALIZED; }
  inline bool is_stmt_prepare_or_first_sp_execute() const
  { return (int)state < (int)STMT_PREPARED; }
  inline bool is_stmt_prepare_or_first_stmt_execute() const
  { return (int)state <= (int)STMT_PREPARED; }
  inline bool is_conventional() const
  { return state == STMT_CONVENTIONAL_EXECUTION; }

  inline void* alloc(size_t size) { return alloc_root(mem_root,size); }
  inline void* calloc(size_t size)
  {
    void *ptr;
    if ((ptr=alloc_root(mem_root,size)))
      memset(ptr, 0, size);
    return ptr;
  }
  inline char *strdup(const char *str)
  { return strdup_root(mem_root,str); }
  inline char *strmake(const char *str, size_t size)
  { return strmake_root(mem_root,str,size); }
  inline void *memdup(const void *str, size_t size)
  { return memdup_root(mem_root,str,size); }
  inline void *memdup_w_gap(const void *str, size_t size, uint gap)
  {
    void *ptr;
    if ((ptr= alloc_root(mem_root,size+gap)))
      memcpy(ptr,str,size);
    return ptr;
  }

  void set_query_arena(Query_arena *set);

  void free_items();
  /* Close the active state associated with execution of this statement */
  virtual void cleanup_stmt();
};


class Server_side_cursor;

class Statement: public Query_arena
{
  Statement(const Statement &rhs);              /* not implemented: */
  Statement &operator=(const Statement &rhs);   /* non-copyable */
public:
  /*
    Uniquely identifies each statement object in thread scope; change during
    statement lifetime. FIXME: must be const
  */
   ulong id;

  /*
    MARK_COLUMNS_NONE:  Means mark_used_colums is not set and no indicator to
                        handler of fields used is set
    MARK_COLUMNS_READ:  Means a bit in read set is set to inform handler
                        that the field is to be read. If field list contains
                        duplicates, then thd->dup_field is set to point
                        to the last found duplicate.
    MARK_COLUMNS_WRITE: Means a bit is set in write set to inform handler
                        that it needs to update this field in write_row
                        and update_row.
  */
  enum enum_mark_columns mark_used_columns;

  LEX_STRING name; /* name for named prepared statements */
  LEX *lex;                                     // parse tree descriptor
  /*
    Points to the query associated with this statement. It's const, but
    we need to declare it char * because all table handlers are written
    in C and need to point to it.

    Note that if we set query = NULL, we must at the same time set
    query_length = 0, and protect the whole operation with
    LOCK_thd_data mutex. To avoid crashes in races, if we do not
    know that thd->query cannot change at the moment, we should print
    thd->query like this:
      (1) reserve the LOCK_thd_data mutex;
      (2) print or copy the value of query and query_length
      (3) release LOCK_thd_data mutex.
    This printing is needed at least in SHOW PROCESSLIST and SHOW
    ENGINE INNODB STATUS.
  */
  CSET_STRING query_string;

  /*
    In some cases, we may want to modify the query (i.e. replace
    passwords with their hashes before logging the statement etc.).

    In case the query was rewritten, the original query will live in
    query_string, while the rewritten query lives in rewritten_query.
    If rewritten_query is empty, query_string should be logged.
    If rewritten_query is non-empty, the rewritten query it contains
    should be used in logs (general log, slow query log, binary log).

    Currently, password obfuscation is the only rewriting we do; more
    may follow at a later date, both pre- and post parsing of the query.
    Rewriting of binloggable statements must preserve all pertinent
    information.
  */
  String      rewritten_query;

  inline char *query() const { return query_string.str(); }
  inline uint32 query_length() const { return (uint32)query_string.length(); }
  const CHARSET_INFO *query_charset() const { return query_string.charset(); }
  void set_query_inner(const CSET_STRING &string_arg)
  {
    query_string= string_arg;
  }
  void set_query_inner(char *query_arg, uint32 query_length_arg,
                       const CHARSET_INFO *cs_arg)
  {
    set_query_inner(CSET_STRING(query_arg, query_length_arg, cs_arg));
  }
  void reset_query_inner()
  {
    set_query_inner(CSET_STRING());
  }
  char *db;
  size_t db_length;

public:

  /* This constructor is called for backup statements */
  Statement() {}

  Statement(LEX *lex_arg, MEM_ROOT *mem_root_arg,
            enum_state state_arg, ulong id_arg);
  virtual ~Statement();

  /* Assign execution context (note: not all members) of given stmt to self */
  virtual void set_statement(Statement *stmt);
  void set_n_backup_statement(Statement *stmt, Statement *backup);
  void restore_backup_statement(Statement *stmt, Statement *backup);
  /* return class type */
  virtual Type type() const;
};


class Statement_map
{
public:
  Statement_map();

  int insert(THD *thd, Statement *statement);

  Statement *find_by_name(LEX_STRING *name)
  {
    Statement *stmt;
    stmt= (Statement*)my_hash_search(&names_hash, (uchar*)name->str,
                                     name->length);
    return stmt;
  }

  Statement *find(ulong id)
  {
    if (last_found_statement == 0 || id != last_found_statement->id)
    {
      Statement *stmt;
      stmt= (Statement *) my_hash_search(&st_hash, (uchar *) &id, sizeof(id));
      if (stmt && stmt->name.str)
        return NULL;
      last_found_statement= stmt;
    }
    return last_found_statement;
  }
  /*
    Close all cursors of this connection that use tables of a storage
    engine that has transaction-specific state and therefore can not
    survive COMMIT or ROLLBACK. Currently all but MyISAM cursors are closed.
    CURRENTLY NOT IMPLEMENTED!
  */
  void close_transient_cursors();
  void erase(Statement *statement);
  /* Erase all statements (calls Statement destructor) */
  void reset();
  ~Statement_map();
private:
  HASH st_hash;
  HASH names_hash;
  Statement *last_found_statement;
};

class Ha_trx_info;

struct THD_TRANS
{
  /* true is not all entries in the ht[] support 2pc */
  bool        no_2pc;
  int         rw_ha_count;
  /* storage engines that registered in this transaction */
  Ha_trx_info *ha_list;

private:
  /* 
    The purpose of this member variable (i.e. flag) is to keep track of
    statements which cannot be rolled back safely(completely).
    For example,

    * statements that modified non-transactional tables. The value
    MODIFIED_NON_TRANS_TABLE is set within mysql_insert, mysql_update,
    mysql_delete, etc if a non-transactional table is modified.

    * 'DROP TEMPORARY TABLE' and 'CREATE TEMPORARY TABLE' statements.
    The former sets the value CREATED_TEMP_TABLE is set and the latter
    the value DROPPED_TEMP_TABLE.
    
    The tracked statements are modified in scope of:

    * transaction, when the variable is a member of THD::transaction.all
    
    * top-level statement or sub-statement, when the variable is a
    member of THD::transaction.stmt

    This member has the following life cycle:

    * stmt.m_unsafe_rollback_flags is used to keep track of top-level statements
    which cannot be rolled back safely. At the end of the statement, the value
    of stmt.m_unsafe_rollback_flags is merged with all.m_unsafe_rollback_flags
    and gets reset.
    
    * all.cannot_safely_rollback is reset at the end of transaction

    * Since we do not have a dedicated context for execution of a sub-statement,
    to keep track of non-transactional changes in a sub-statement, we re-use
    stmt.m_unsafe_rollback_flags. At entrance into a sub-statement, a copy of
    the value of stmt.m_unsafe_rollback_flags (containing the changes of the
    outer statement) is saved on stack.  Then stmt.m_unsafe_rollback_flags is
    reset to 0 and the substatement is executed. Then the new value is merged
    with the saved value.
  */

  unsigned int m_unsafe_rollback_flags;
  /*
    Define the type of statemens which cannot be rolled back safely.
    Each type occupies one bit in m_unsafe_rollback_flags.
  */
  static unsigned int const MODIFIED_NON_TRANS_TABLE= 0x01;
  static unsigned int const CREATED_TEMP_TABLE= 0x02;
  static unsigned int const DROPPED_TEMP_TABLE= 0x04;

public:
#ifndef DBUG_OFF
  void dbug_unsafe_rollback_flags(const char* msg) const
  {
    DBUG_PRINT("debug", ("%s.unsafe_rollback_flags: %s%s%s",
                         msg,
                         FLAGSTR(m_unsafe_rollback_flags, MODIFIED_NON_TRANS_TABLE),
                         FLAGSTR(m_unsafe_rollback_flags, CREATED_TEMP_TABLE),
                         FLAGSTR(m_unsafe_rollback_flags, DROPPED_TEMP_TABLE)));
  }
#endif

  bool cannot_safely_rollback() const
  {
    return m_unsafe_rollback_flags > 0;
  }
  unsigned int get_unsafe_rollback_flags() const
  {
    return m_unsafe_rollback_flags;
  }
  void set_unsafe_rollback_flags(unsigned int flags)
  {
    DBUG_PRINT("debug", ("set_unsafe_rollback_flags: %d", flags));
    m_unsafe_rollback_flags= flags;
  }
  void add_unsafe_rollback_flags(unsigned int flags)
  {
    DBUG_PRINT("debug", ("add_unsafe_rollback_flags: %d", flags));
    m_unsafe_rollback_flags|= flags;
  }
  void reset_unsafe_rollback_flags()
  {
    DBUG_PRINT("debug", ("reset_unsafe_rollback_flags"));
    m_unsafe_rollback_flags= 0;
  }
  void mark_modified_non_trans_table()
  {
    DBUG_PRINT("debug", ("mark_modified_non_trans_table"));
    m_unsafe_rollback_flags|= MODIFIED_NON_TRANS_TABLE;
  }
  bool has_modified_non_trans_table() const
  {
    return m_unsafe_rollback_flags & MODIFIED_NON_TRANS_TABLE;
  }
  void mark_created_temp_table()
  {
    DBUG_PRINT("debug", ("mark_created_temp_table"));
    m_unsafe_rollback_flags|= CREATED_TEMP_TABLE;
  }
  bool has_created_temp_table() const
  {
    return m_unsafe_rollback_flags & CREATED_TEMP_TABLE;
  }
  void mark_dropped_temp_table()
  {
    DBUG_PRINT("debug", ("mark_dropped_temp_table"));
    m_unsafe_rollback_flags|= DROPPED_TEMP_TABLE;
  }
  bool has_dropped_temp_table() const
  {
    return m_unsafe_rollback_flags & DROPPED_TEMP_TABLE;
  }

  void reset()
  {
    no_2pc= FALSE;
    rw_ha_count= 0;
    reset_unsafe_rollback_flags();
  }
  bool is_empty() const { return ha_list == NULL; }
};

class Ha_trx_info
{
#ifndef DBUG_OFF
  friend const char *
  ha_list_names(Ha_trx_info *ha_list, char *const buf_arg)
  {
    char *buf = buf_arg;
    while (ha_list)
    {
      buf += sprintf(buf, "%s", ha_legacy_type_name(ha_list->m_ht->db_type));
      ha_list = ha_list->m_next;
      if (ha_list)
        buf += sprintf(buf, ", ");
    }
    if (buf == buf_arg)
      sprintf(buf, "<NONE>");
    return buf_arg;
  }
#endif

public:
  void register_ha(THD_TRANS *trans, handlerton *ht_arg)
  {
    DBUG_ENTER("Ha_trx_info::register_ha");
    DBUG_PRINT("enter", ("trans: 0x%llx, ht: 0x%llx (%s)",
                         (ulonglong) trans, (ulonglong) ht_arg,
                         ha_legacy_type_name(ht_arg->db_type)));
    DBUG_ASSERT(m_flags == 0);
    DBUG_ASSERT(m_ht == NULL);
    DBUG_ASSERT(m_next == NULL);

    m_ht= ht_arg;
    m_flags= (int) TRX_READ_ONLY; /* Assume read-only at start. */

    m_next= trans->ha_list;
    trans->ha_list= this;
    DBUG_VOID_RETURN;
  }

  void reset()
  {
    DBUG_ENTER("Ha_trx_info::reset");
    m_next= NULL;
    m_ht= NULL;
    m_flags= 0;
    DBUG_VOID_RETURN;
  }

  Ha_trx_info() { reset(); }

  void set_trx_read_write()
  {
    DBUG_ASSERT(is_started());
    m_flags|= (int) TRX_READ_WRITE;
  }
  bool is_trx_read_write() const
  {
    DBUG_ASSERT(is_started());
    return m_flags & (int) TRX_READ_WRITE;
  }
  bool is_started() const { return m_ht != NULL; }
  void coalesce_trx_with(const Ha_trx_info *stmt_trx)
  {
    /*
      Must be called only after the transaction has been started.
      Can be called many times, e.g. when we have many
      read-write statements in a transaction.
    */
    DBUG_ASSERT(is_started());
    if (stmt_trx->is_trx_read_write())
      set_trx_read_write();
  }
  Ha_trx_info *next() const
  {
    DBUG_ASSERT(is_started());
    return m_next;
  }
  handlerton *ht() const
  {
    DBUG_ASSERT(is_started());
    return m_ht;
  }
private:
  enum { TRX_READ_ONLY= 0, TRX_READ_WRITE= 1 };
  Ha_trx_info *m_next;
  handlerton *m_ht;
  uchar       m_flags;
};

struct st_savepoint {
  struct st_savepoint *prev;
  char                *name;
  uint                 length;
  Ha_trx_info         *ha_list;
  MDL_savepoint        mdl_savepoint;
};

enum xa_states {XA_NOTR=0, XA_ACTIVE, XA_IDLE, XA_PREPARED, XA_ROLLBACK_ONLY};
extern const char *xa_state_names[];

typedef struct st_xid_state {
  /* For now, this is only used to catch duplicated external xids */
  XID  xid;                           // transaction identifier
  enum xa_states xa_state;            // used by external XA only
  bool in_thd;
  /* Error reported by the Resource Manager (RM) to the Transaction Manager. */
  uint rm_error;
} XID_STATE;

extern mysql_mutex_t LOCK_xid_cache;
extern HASH xid_cache;
bool xid_cache_init(void);
void xid_cache_free(void);
XID_STATE *xid_cache_search(XID *xid);
bool xid_cache_insert(XID *xid, enum xa_states xa_state);
bool xid_cache_insert(XID_STATE *xid_state);
void xid_cache_delete(XID_STATE *xid_state);

class Security_context {
private:

String host;
String ip;
String external_user;
public:
  Security_context() {}                       /* Remove gcc warning */
  /*
    host - host of the client
    user - user of the client, set to NULL until the user has been read from
    the connection
    priv_user - The user privilege we are using. May be "" for anonymous user.
    ip - client IP
  */
  char   *user;
  char   priv_user[USERNAME_LENGTH];
  char   proxy_user[USERNAME_LENGTH + MAX_HOSTNAME + 5];
  /* The host privilege we are using */
  char   priv_host[MAX_HOSTNAME];
  /* points to host if host is available, otherwise points to ip */
  const char *host_or_ip;
  ulong master_access;                 /* Global privileges from mysql.user */
  ulong db_access;                     /* Privileges for current db */
  /*
    This flag is set according to connecting user's context and not the
    effective user.
  */
  bool password_expired;               /* password expiration flag */

  void init();
  void destroy();
  void skip_grants();
  inline char *priv_host_name()
  {
    return (*priv_host ? priv_host : (char *)"%");
  }
  
  bool set_user(char *user_arg);
  String *get_host();
  String *get_ip();
  String *get_external_user();
  void set_host(const char *p);
  void set_ip(const char *p);
  void set_external_user(const char *p);
  void set_host(const char *str, size_t len);
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  bool
  change_security_context(THD *thd,
                          LEX_STRING *definer_user,
                          LEX_STRING *definer_host,
                          LEX_STRING *db,
                          Security_context **backup);

  void
  restore_security_context(THD *thd, Security_context *backup);
#endif
  bool user_matches(Security_context *);
};


class Log_throttle
{
  ulonglong window_end;

  const ulong window_size;

  ulong count;

protected:
  const char *summary_template;

  void new_window(ulonglong now);

  bool inc_log_count(ulong rate) { return (++count > rate); }

  bool in_window(ulonglong now) const { return (now < window_end); };

  ulong prepare_summary(ulong rate);

  Log_throttle(ulong window_usecs, const char *msg)
              : window_end(0), window_size(window_usecs),
                count(0), summary_template(msg)
  {}

public:
  static const ulong LOG_THROTTLE_WINDOW_SIZE= 60000000;
};


class Slow_log_throttle : public Log_throttle
{
private:
  Security_context aggregate_sctx;

  ulonglong total_exec_time;

  ulonglong total_lock_time;

  ulong *rate;

  bool (*log_summary)(THD *, const char *, uint);

  mysql_mutex_t *LOCK_log_throttle;

  void new_window(ulonglong now);

  void print_summary(THD *thd, ulong suppressed,
                     ulonglong print_lock_time,
                     ulonglong print_exec_time);

public:

  Slow_log_throttle(ulong *threshold, mysql_mutex_t *lock, ulong window_usecs,
                    bool (*logger)(THD *, const char *, uint),
                    const char *msg);

  bool flush(THD *thd);

  bool log(THD *thd, bool eligible);
};


class Error_log_throttle : public Log_throttle
{
private:
  void (*log_summary)(const char *, ...);

  void print_summary(ulong suppressed)
  {
    (*log_summary)(summary_template, suppressed);
  }

public:
  Error_log_throttle(ulong window_usecs,
                     void (*logger)(const char*, ...),
                     const char *msg)
  : Log_throttle(window_usecs, msg), log_summary(logger)
  {}

  bool flush(THD *thd);

  bool log(THD *thd);
};


extern Slow_log_throttle log_throttle_qni;


struct Item_change_record: public ilink<Item_change_record>
{
  Item **place;
  Item *old_value;
};

typedef I_List<Item_change_record> Item_change_list;


enum enum_locked_tables_mode
{
  LTM_NONE= 0,
  LTM_LOCK_TABLES,
  LTM_PRELOCKED,
  LTM_PRELOCKED_UNDER_LOCK_TABLES
};


class Open_tables_state
{
private:
  Dynamic_array<Reprepare_observer *> m_reprepare_observers;

public:
  Reprepare_observer *get_reprepare_observer() const
  {
    return
      m_reprepare_observers.elements() > 0 ?
      *m_reprepare_observers.back() :
      NULL;
  }

  void push_reprepare_observer(Reprepare_observer *o)
  { m_reprepare_observers.append(o); }

  Reprepare_observer *pop_reprepare_observer()
  { return m_reprepare_observers.pop(); }

  void reset_reprepare_observers()
  { m_reprepare_observers.clear(); }

public:
  TABLE *open_tables;
  TABLE *temporary_tables;
  TABLE *derived_tables;
  /*
    During a MySQL session, one can lock tables in two modes: automatic
    or manual. In automatic mode all necessary tables are locked just before
    statement execution, and all acquired locks are stored in 'lock'
    member. Unlocking takes place automatically as well, when the
    statement ends.
    Manual mode comes into play when a user issues a 'LOCK TABLES'
    statement. In this mode the user can only use the locked tables.
    Trying to use any other tables will give an error.
    The locked tables are also stored in this member, however,
    thd->locked_tables_mode is turned on.  Manual locking is described in
    the 'LOCK_TABLES' chapter of the MySQL manual.
    See also lock_tables() for details.
  */
  MYSQL_LOCK *lock;

  /*
    CREATE-SELECT keeps an extra lock for the table being
    created. This field is used to keep the extra lock available for
    lower level routines, which would otherwise miss that lock.
   */
  MYSQL_LOCK *extra_lock;

  /*
    Enum enum_locked_tables_mode and locked_tables_mode member are
    used to indicate whether the so-called "locked tables mode" is on,
    and what kind of mode is active.

    Locked tables mode is used when it's necessary to open and
    lock many tables at once, for usage across multiple
    (sub-)statements.
    This may be necessary either for queries that use stored functions
    and triggers, in which case the statements inside functions and
    triggers may be executed many times, or for implementation of
    LOCK TABLES, in which case the opened tables are reused by all
    subsequent statements until a call to UNLOCK TABLES.

    The kind of locked tables mode employed for stored functions and
    triggers is also called "prelocked mode".
    In this mode, first open_tables() call to open the tables used
    in a statement analyses all functions used by the statement
    and adds all indirectly used tables to the list of tables to
    open and lock.
    It also marks the parse tree of the statement as requiring
    prelocking. After that, lock_tables() locks the entire list
    of tables and changes THD::locked_tables_modeto LTM_PRELOCKED.
    All statements executed inside functions or triggers
    use the prelocked tables, instead of opening their own ones.
    Prelocked mode is turned off automatically once close_thread_tables()
    of the main statement is called.
  */
  enum enum_locked_tables_mode locked_tables_mode;
  uint current_tablenr;

  enum enum_flags {
    BACKUPS_AVAIL = (1U << 0)     /* There are backups available */
  };

  /*
    Flags with information about the open tables state.
  */
  uint state_flags;
  Open_tables_state() : state_flags(0U) { }

  void set_open_tables_state(Open_tables_state *state);

  void reset_open_tables_state();
};


class Open_tables_backup: public Open_tables_state
{
public:
  MDL_savepoint mdl_system_tables_svp;
};

/* Defines used for Sub_statement_state::in_sub_stmt */

#define SUB_STMT_TRIGGER 1
#define SUB_STMT_FUNCTION 2


class Sub_statement_state
{
public:
  ulonglong option_bits;
  ulonglong first_successful_insert_id_in_prev_stmt;
  ulonglong first_successful_insert_id_in_cur_stmt, insert_id_for_cur_row;
  Discrete_interval auto_inc_interval_for_cur_row;
  Discrete_intervals_list auto_inc_intervals_forced;
  ulonglong limit_found_rows;
  ha_rows    cuted_fields, sent_row_count, examined_row_count;
  ulong client_capabilities;
  uint in_sub_stmt;
  bool enable_slow_log;
  bool last_insert_id_used;
  SAVEPOINT *savepoints;
  enum enum_check_fields count_cuted_fields;
};


/* Flags for the THD::system_thread variable */
enum enum_thread_type
{
  NON_SYSTEM_THREAD= 0,
  SYSTEM_THREAD_DELAYED_INSERT= 1,
  SYSTEM_THREAD_SLAVE_IO= 2,
  SYSTEM_THREAD_SLAVE_SQL= 4,
  SYSTEM_THREAD_NDBCLUSTER_BINLOG= 8,
  SYSTEM_THREAD_EVENT_SCHEDULER= 16,
  SYSTEM_THREAD_EVENT_WORKER= 32,
  SYSTEM_THREAD_INFO_REPOSITORY= 64,
  SYSTEM_THREAD_SLAVE_WORKER= 128
};

inline char const *
show_system_thread(enum_thread_type thread)
{
#define RETURN_NAME_AS_STRING(NAME) case (NAME): return #NAME
  switch (thread) {
    static char buf[64];
    RETURN_NAME_AS_STRING(NON_SYSTEM_THREAD);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_DELAYED_INSERT);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_SLAVE_IO);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_SLAVE_SQL);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_NDBCLUSTER_BINLOG);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_EVENT_SCHEDULER);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_EVENT_WORKER);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_INFO_REPOSITORY);
    RETURN_NAME_AS_STRING(SYSTEM_THREAD_SLAVE_WORKER);
  default:
    sprintf(buf, "<UNKNOWN SYSTEM THREAD: %d>", thread);
    return buf;
  }
#undef RETURN_NAME_AS_STRING
}

class Internal_error_handler
{
protected:
  Internal_error_handler() :
    m_prev_internal_handler(NULL)
  {}

  virtual ~Internal_error_handler() {}

public:
  virtual bool handle_condition(THD *thd,
                                uint sql_errno,
                                const char* sqlstate,
                                Sql_condition::enum_warning_level level,
                                const char* msg,
                                Sql_condition ** cond_hdl) = 0;

private:
  Internal_error_handler *m_prev_internal_handler;
  friend class THD;
};


class Dummy_error_handler : public Internal_error_handler
{
public:
  bool handle_condition(THD *thd,
                        uint sql_errno,
                        const char* sqlstate,
                        Sql_condition::enum_warning_level level,
                        const char* msg,
                        Sql_condition ** cond_hdl)
  {
    /* Ignore error */
    return TRUE;
  }
};


class Drop_table_error_handler : public Internal_error_handler
{
public:
  Drop_table_error_handler() {}

public:
  bool handle_condition(THD *thd,
                        uint sql_errno,
                        const char* sqlstate,
                        Sql_condition::enum_warning_level level,
                        const char* msg,
                        Sql_condition ** cond_hdl);

private:
};


class Locked_tables_list
{
private:
  MEM_ROOT m_locked_tables_root;
  TABLE_LIST *m_locked_tables;
  TABLE_LIST **m_locked_tables_last;
  TABLE **m_reopen_array;
  size_t m_locked_tables_count;
public:
  Locked_tables_list()
    :m_locked_tables(NULL),
    m_locked_tables_last(&m_locked_tables),
    m_reopen_array(NULL),
    m_locked_tables_count(0)
  {
    init_sql_alloc(&m_locked_tables_root, MEM_ROOT_BLOCK_SIZE, 0);
  }
  void unlock_locked_tables(THD *thd);
  ~Locked_tables_list()
  {
    unlock_locked_tables(0);
  }
  bool init_locked_tables(THD *thd);
  TABLE_LIST *locked_tables() { return m_locked_tables; }
  void unlink_from_list(THD *thd, TABLE_LIST *table_list,
                        bool remove_from_locked_tables);
  void unlink_all_closed_tables(THD *thd,
                                MYSQL_LOCK *lock,
                                size_t reopen_count);
  bool reopen_tables(THD *thd);
};


struct Ha_data
{
  void *ha_ptr;
  Ha_trx_info ha_info[2];
  plugin_ref lock;
  Ha_data() :ha_ptr(NULL) {}
};

class Global_read_lock
{
public:
  enum enum_grl_state
  {
    GRL_NONE,
    GRL_ACQUIRED,
    GRL_ACQUIRED_AND_BLOCKS_COMMIT
  };

  Global_read_lock()
    : m_state(GRL_NONE),
      m_mdl_global_shared_lock(NULL),
      m_mdl_blocks_commits_lock(NULL)
  {}

  bool lock_global_read_lock(THD *thd);
  void unlock_global_read_lock(THD *thd);

  static bool global_read_lock_active()
  {
    return my_atomic_load32(&m_active_requests) ? true : false;
  }

  bool can_acquire_protection() const
  {
    if (m_state)
    {
      my_error(ER_CANT_UPDATE_WITH_READLOCK, MYF(0));
      return TRUE;
    }
    return FALSE;
  }
  bool make_global_read_lock_block_commit(THD *thd);
  bool is_acquired() const { return m_state != GRL_NONE; }
  void set_explicit_lock_duration(THD *thd);
private:
  volatile static int32 m_active_requests;
  enum_grl_state m_state;
  MDL_ticket *m_mdl_global_shared_lock;
  MDL_ticket *m_mdl_blocks_commits_lock;
};

extern "C" void my_message_sql(uint error, const char *str, myf MyFlags);


/*
  Convert microseconds since epoch to timeval.
  @param     micro_time  Microseconds.
  @param OUT tm          A timeval variable to write to.
*/
static inline void
my_micro_time_to_timeval(ulonglong micro_time, struct timeval *tm)
{
  tm->tv_sec=  (long) (micro_time / 1000000);
  tm->tv_usec= (long) (micro_time % 1000000);
}

class THD :public MDL_context_owner,
           public Statement,
           public Open_tables_state
{
private:
  inline bool is_stmt_prepare() const
  { DBUG_ASSERT(0); return Statement::is_stmt_prepare(); }

  inline bool is_stmt_prepare_or_first_sp_execute() const
  { DBUG_ASSERT(0); return Statement::is_stmt_prepare_or_first_sp_execute(); }

  inline bool is_stmt_prepare_or_first_stmt_execute() const
  { DBUG_ASSERT(0); return Statement::is_stmt_prepare_or_first_stmt_execute(); }

  inline bool is_conventional() const
  { DBUG_ASSERT(0); return Statement::is_conventional(); }

public:
  MDL_context mdl_context;

  /* Used to execute base64 coded binlog events in MySQL server */
  Relay_log_info* rli_fake;
  /* Slave applier execution context */
  Relay_log_info* rli_slave;

  void reset_for_next_command();
  /*
    Constant for THD::where initialization in the beginning of every query.

    It's needed because we do not save/restore THD::where normally during
    primary (non subselect) query execution.
  */
  static const char * const DEFAULT_WHERE;

#ifdef EMBEDDED_LIBRARY
  struct st_mysql  *mysql;
  unsigned long  client_stmt_id;
  unsigned long  client_param_count;
  struct st_mysql_bind *client_params;
  char *extra_data;
  ulong extra_length;
  struct st_mysql_data *cur_data;
  struct st_mysql_data *first_data;
  struct st_mysql_data **data_tail;
  void clear_data_list();
  struct st_mysql_data *alloc_new_dataset();
  /*
    In embedded server it points to the statement that is processed
    in the current query. We store some results directly in statement
    fields then.
  */
  struct st_mysql_stmt *current_stmt;
#endif
#ifdef HAVE_QUERY_CACHE
  Query_cache_tls query_cache_tls;
#endif
  NET     net;                          // client connection descriptor
  NET_SERVER m_net_server_extension;
  Protocol *protocol;                   // Current protocol
  Protocol_text   protocol_text;        // Normal protocol
  Protocol_binary protocol_binary;      // Binary protocol
  HASH    user_vars;                    // hash for user variables
  String  packet;                       // dynamic buffer for network I/O
  String  convert_buffer;               // buffer for charset conversions
  struct  rand_struct rand;             // used for authentication
  struct  system_variables variables;   // Changeable local variables
  struct  system_status_var status_var; // Per thread statistic vars
  struct  system_status_var *initial_status_var; /* used by show status */
  THR_LOCK_INFO lock_info;              // Locking info of this thread
  mysql_mutex_t LOCK_thd_data;

  /* all prepared statements and cursors of this connection */
  Statement_map stmt_map;
  /*
    A pointer to the stack frame of handle_one_connection(),
    which is called first in the thread for handling a client
  */
  char    *thread_stack;

  char *catalog;

  Security_context main_security_ctx;
  Security_context *security_ctx;

  /*
    Points to info-string that we show in SHOW PROCESSLIST
    You are supposed to update thd->proc_info only if you have coded
    a time-consuming piece that MySQL can get stuck in for a long time.

    Set it using the  thd_proc_info(THD *thread, const char *message)
    macro/function.

    This member is accessed and assigned without any synchronization.
    Therefore, it may point only to constant (statically
    allocated) strings, which memory won't go away over time.
  */
  const char *proc_info;

private:
  unsigned int m_current_stage_key;

public:
  void enter_stage(const PSI_stage_info *stage,
                   PSI_stage_info *old_stage,
                   const char *calling_func,
                   const char *calling_file,
                   const unsigned int calling_line);

  const char *get_proc_info() const
  { return proc_info; }

  /*
    Used in error messages to tell user in what part of MySQL we found an
    error. E. g. when where= "having clause", if fix_fields() fails, user
    will know that the error was in having clause.
  */
  const char *where;

  ulong client_capabilities;            /* What the client supports */
  ulong max_client_packet_length;

  HASH          handler_tables_hash;
  /*
    One thread can hold up to one named user-level lock. This variable
    points to a lock object if the lock is present. See item_func.cc and
    chapter 'Miscellaneous functions', for functions GET_LOCK, RELEASE_LOCK. 
  */
  User_level_lock *ull;
#ifndef DBUG_OFF
  uint dbug_sentry; // watch out for memory corruption
#endif
  struct st_my_thread_var *mysys_var;

private:
  enum enum_server_command m_command;

public:
  uint32     unmasked_server_id;
  uint32     server_id;
  uint32     file_id;                   // for LOAD DATA INFILE
  /* remote (peer) port */
  uint16 peer_port;
  struct timeval start_time;
  struct timeval user_time;
  // track down slow pthread_create
  ulonglong  prior_thr_create_utime, thr_create_utime;
  ulonglong  start_utime, utime_after_lock;

  thr_lock_type update_lock_default;
  Delayed_insert *di;

  /* <> 0 if we are inside of trigger or stored function. */
  uint in_sub_stmt;

  uint fill_status_recursion_level;
  uint fill_variables_recursion_level;

  /* container for handler's private per-connection data */
  Ha_data ha_data[MAX_HA];

  /*
    Position of first event in Binlog
    *after* last event written by this
    thread.
  */
  event_coordinates binlog_next_event_pos;
  void set_next_event_pos(const char* _filename, ulonglong _pos);
  void clear_next_event_pos();

  /*
     Ptr to row event extra data to be written to Binlog /
     received from Binlog.

   */
  uchar* binlog_row_event_extra_data;
  static bool binlog_row_event_extra_data_eq(const uchar* a,
                                             const uchar* b);

#ifndef MYSQL_CLIENT
  int binlog_setup_trx_data();

  /*
    Public interface to write RBR events to the binlog
  */
  int binlog_write_table_map(TABLE *table, bool is_transactional,
                             bool binlog_rows_query);
  int binlog_write_row(TABLE* table, bool is_transactional,
                       const uchar *new_data,
                       const uchar* extra_row_info);
  int binlog_delete_row(TABLE* table, bool is_transactional,
                        const uchar *old_data,
                        const uchar* extra_row_info);
  int binlog_update_row(TABLE* table, bool is_transactional,
                        const uchar *old_data, const uchar *new_data,
                        const uchar* extra_row_info);
  void binlog_prepare_row_images(TABLE* table);

  void set_server_id(uint32 sid) { server_id = sid; }

  /*
    Member functions to handle pending event for row-level logging.
  */
  template <class RowsEventT> Rows_log_event*
    binlog_prepare_pending_rows_event(TABLE* table, uint32 serv_id,
                                      size_t needed,
                                      bool is_transactional,
                                      RowsEventT* hint,
                                      const uchar* extra_row_info);
  Rows_log_event* binlog_get_pending_rows_event(bool is_transactional) const;
  inline int binlog_flush_pending_rows_event(bool stmt_end)
  {
    return (binlog_flush_pending_rows_event(stmt_end, FALSE) || 
            binlog_flush_pending_rows_event(stmt_end, TRUE));
  }
  int binlog_flush_pending_rows_event(bool stmt_end, bool is_transactional);

  int is_current_stmt_binlog_format_row() const {
    DBUG_ASSERT(current_stmt_binlog_format == BINLOG_FORMAT_STMT ||
                current_stmt_binlog_format == BINLOG_FORMAT_ROW);
    return current_stmt_binlog_format == BINLOG_FORMAT_ROW;
  }
  inline bool optimizer_switch_flag(ulonglong flag) const
  {
    return (variables.optimizer_switch & flag);
  }

  enum binlog_filter_state
  {
    BINLOG_FILTER_UNKNOWN,
    BINLOG_FILTER_CLEAR,
    BINLOG_FILTER_SET
  };

  inline void reset_binlog_local_stmt_filter()
  {
    m_binlog_filter_state= BINLOG_FILTER_UNKNOWN;
  }

  inline void clear_binlog_local_stmt_filter()
  {
    DBUG_ASSERT(m_binlog_filter_state == BINLOG_FILTER_UNKNOWN);
    m_binlog_filter_state= BINLOG_FILTER_CLEAR;
  }

  inline void set_binlog_local_stmt_filter()
  {
    DBUG_ASSERT(m_binlog_filter_state == BINLOG_FILTER_UNKNOWN);
    m_binlog_filter_state= BINLOG_FILTER_SET;
  }

  inline binlog_filter_state get_binlog_local_stmt_filter()
  {
    return m_binlog_filter_state;
  }

private:
  binlog_filter_state m_binlog_filter_state;

  enum_binlog_format current_stmt_binlog_format;

  uint32 binlog_unsafe_warning_flags;

  /*
    Number of outstanding table maps, i.e., table maps in the
    transaction cache.
  */
  uint binlog_table_maps;
  /*
    MTS: db names listing to be updated by the query databases
  */
  List<char> *binlog_accessed_db_names;

  const char *m_trans_log_file;
  char *m_trans_fixed_log_file;
  my_off_t m_trans_end_pos;
public:
  void issue_unsafe_warnings();

  uint get_binlog_table_maps() const {
    return binlog_table_maps;
  }
  void clear_binlog_table_maps() {
    binlog_table_maps= 0;
  }

  /*
    MTS: accessor to binlog_accessed_db_names list
  */
  List<char> * get_binlog_accessed_db_names()
  {
    return binlog_accessed_db_names;
  }

  /*
     MTS: resetter of binlog_accessed_db_names list normally
     at the end of the query execution
  */
  void clear_binlog_accessed_db_names() { binlog_accessed_db_names= NULL; }

  /* MTS: method inserts a new unique name into binlog_updated_dbs */
  void add_to_binlog_accessed_dbs(const char *db);

#endif /* MYSQL_CLIENT */

public:

  struct st_transactions {
    SAVEPOINT *savepoints;
    THD_TRANS all;                      // Trans since BEGIN WORK
    THD_TRANS stmt;                     // Trans for current statement
    XID_STATE xid_state;
    Rows_log_event *m_pending_rows_event;

    /*
       Tables changed in transaction (that must be invalidated in query cache).
       List contain only transactional tables, that not invalidated in query
       cache (instead of full list of changed in transaction tables).
    */
    CHANGED_TABLE_LIST* changed_tables;
    MEM_ROOT mem_root; // Transaction-life memory allocation pool

    /*
      (Mostly) binlog-specific fields use while flushing the caches
      and committing transactions.
      We don't use bitfield any more in the struct. Modification will
      be lost when concurrently updating multiple bit fields. It will
      cause a race condition in a multi-threaded application. And we
      already caught a race condition case between xid_written and
      ready_preempt in MYSQL_BIN_LOG::ordered_commit.
    */
    struct {
      bool enabled;                   // see ha_enable_transaction()
      bool pending;                   // Is the transaction commit pending?
      bool xid_written;               // The session wrote an XID
      bool real_commit;               // Is this a "real" commit?
      bool commit_low;                // see MYSQL_BIN_LOG::ordered_commit
      bool run_hooks;                 // Call the after_commit hook
#ifndef DBUG_OFF
      bool ready_preempt;             // internal in MYSQL_BIN_LOG::ordered_commit
#endif
    } flags;

    void cleanup()
    {
      DBUG_ENTER("THD::st_transaction::cleanup");
      changed_tables= 0;
      savepoints= 0;

      /*
        If rm_error is raised, it means that this piece of a distributed
        transaction has failed and must be rolled back. But the user must
        rollback it explicitly, so don't start a new distributed XA until
        then.
      */
      if (!xid_state.rm_error)
        xid_state.xid.null();
      free_root(&mem_root,MYF(MY_KEEP_PREALLOC));
      DBUG_VOID_RETURN;
    }
    my_bool is_active()
    {
      return (all.ha_list != NULL);
    }
    st_transactions()
    {
      memset(this, 0, sizeof(*this));
      xid_state.xid.null();
      init_sql_alloc(&mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
    }
    void push_unsafe_rollback_warnings(THD *thd)
    {
      if (all.has_modified_non_trans_table())
        push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                     ER_WARNING_NOT_COMPLETE_ROLLBACK,
                     ER(ER_WARNING_NOT_COMPLETE_ROLLBACK));

      if (all.has_created_temp_table())
        push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                     ER_WARNING_NOT_COMPLETE_ROLLBACK_WITH_CREATED_TEMP_TABLE,
                     ER(ER_WARNING_NOT_COMPLETE_ROLLBACK_WITH_CREATED_TEMP_TABLE));

      if (all.has_dropped_temp_table())
        push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                     ER_WARNING_NOT_COMPLETE_ROLLBACK_WITH_DROPPED_TEMP_TABLE,
                     ER(ER_WARNING_NOT_COMPLETE_ROLLBACK_WITH_DROPPED_TEMP_TABLE));
    }
    void merge_unsafe_rollback_flags()
    {
      /*
        Merge stmt.unsafe_rollback_flags to all.unsafe_rollback_flags. If
        the statement cannot be rolled back safely, the transaction including
        this statement definitely cannot rolled back safely.
      */
      all.add_unsafe_rollback_flags(stmt.get_unsafe_rollback_flags());
    }
  } transaction;
  Global_read_lock global_read_lock;
  Field      *dup_field;
#ifndef __WIN__
  sigset_t signals;
#endif
#ifdef SIGNAL_WITH_VIO_SHUTDOWN
  Vio* active_vio;
#endif
  /*
    This is to track items changed during execution of a prepared
    statement/stored procedure. It's created by
    register_item_tree_change() in memory root of THD, and freed in
    rollback_item_tree_changes(). For conventional execution it's always
    empty.
  */
  Item_change_list change_list;

  /*
    A permanent memory area of the statement. For conventional
    execution, the parsed tree and execution runtime reside in the same
    memory root. In this case stmt_arena points to THD. In case of
    a prepared statement or a stored procedure statement, thd->mem_root
    conventionally points to runtime memory, and thd->stmt_arena
    points to the memory of the PS/SP, where the parsed tree of the
    statement resides. Whenever you need to perform a permanent
    transformation of a parsed tree, you should allocate new memory in
    stmt_arena, to allow correct re-execution of PS/SP.
    Note: in the parser, stmt_arena == thd, even for PS/SP.
  */
  Query_arena *stmt_arena;

  /*
    map for tables that will be updated for a multi-table update query
    statement, for other query statements, this will be zero.
  */
  table_map table_map_for_update;

  /* Tells if LAST_INSERT_ID(#) was called for the current statement */
  bool arg_of_last_insert_id_function;
  /*
    ALL OVER THIS FILE, "insert_id" means "*automatically generated* value for
    insertion into an auto_increment column".
  */
  /*
    This is the first autogenerated insert id which was *successfully*
    inserted by the previous statement (exactly, if the previous statement
    didn't successfully insert an autogenerated insert id, then it's the one
    of the statement before, etc).
    It can also be set by SET LAST_INSERT_ID=# or SELECT LAST_INSERT_ID(#).
    It is returned by LAST_INSERT_ID().
  */
  ulonglong  first_successful_insert_id_in_prev_stmt;
  /*
    Variant of the above, used for storing in statement-based binlog. The
    difference is that the one above can change as the execution of a stored
    function progresses, while the one below is set once and then does not
    change (which is the value which statement-based binlog needs).
  */
  ulonglong  first_successful_insert_id_in_prev_stmt_for_binlog;
  /*
    This is the first autogenerated insert id which was *successfully*
    inserted by the current statement. It is maintained only to set
    first_successful_insert_id_in_prev_stmt when statement ends.
  */
  ulonglong  first_successful_insert_id_in_cur_stmt;
  /*
    We follow this logic:
    - when stmt starts, first_successful_insert_id_in_prev_stmt contains the
    first insert id successfully inserted by the previous stmt.
    - as stmt makes progress, handler::insert_id_for_cur_row changes;
    every time get_auto_increment() is called,
    auto_inc_intervals_in_cur_stmt_for_binlog is augmented with the
    reserved interval (if statement-based binlogging).
    - at first successful insertion of an autogenerated value,
    first_successful_insert_id_in_cur_stmt is set to
    handler::insert_id_for_cur_row.
    - when stmt goes to binlog,
    auto_inc_intervals_in_cur_stmt_for_binlog is binlogged if
    non-empty.
    - when stmt ends, first_successful_insert_id_in_prev_stmt is set to
    first_successful_insert_id_in_cur_stmt.
  */
  /*
    stmt_depends_on_first_successful_insert_id_in_prev_stmt is set when
    LAST_INSERT_ID() is used by a statement.
    If it is set, first_successful_insert_id_in_prev_stmt_for_binlog will be
    stored in the statement-based binlog.
    This variable is CUMULATIVE along the execution of a stored function or
    trigger: if one substatement sets it to 1 it will stay 1 until the
    function/trigger ends, thus making sure that
    first_successful_insert_id_in_prev_stmt_for_binlog does not change anymore
    and is propagated to the caller for binlogging.
  */
  bool       stmt_depends_on_first_successful_insert_id_in_prev_stmt;
  /*
    List of auto_increment intervals reserved by the thread so far, for
    storage in the statement-based binlog.
    Note that its minimum is not first_successful_insert_id_in_cur_stmt:
    assuming a table with an autoinc column, and this happens:
    INSERT INTO ... VALUES(3);
    SET INSERT_ID=3; INSERT IGNORE ... VALUES (NULL);
    then the latter INSERT will insert no rows
    (first_successful_insert_id_in_cur_stmt == 0), but storing "INSERT_ID=3"
    in the binlog is still needed; the list's minimum will contain 3.
    This variable is cumulative: if several statements are written to binlog
    as one (stored functions or triggers are used) this list is the
    concatenation of all intervals reserved by all statements.
  */
  Discrete_intervals_list auto_inc_intervals_in_cur_stmt_for_binlog;
  /* Used by replication and SET INSERT_ID */
  Discrete_intervals_list auto_inc_intervals_forced;
  /*
    There is BUG#19630 where statement-based replication of stored
    functions/triggers with two auto_increment columns breaks.
    We however ensure that it works when there is 0 or 1 auto_increment
    column; our rules are
    a) on master, while executing a top statement involving substatements,
    first top- or sub- statement to generate auto_increment values wins the
    exclusive right to see its values be written to binlog (the write
    will be done by the statement or its caller), and the losers won't see
    their values be written to binlog.
    b) on slave, while replicating a top statement involving substatements,
    first top- or sub- statement to need to read auto_increment values from
    the master's binlog wins the exclusive right to read them (so the losers
    won't read their values from binlog but instead generate on their own).
    a) implies that we mustn't backup/restore
    auto_inc_intervals_in_cur_stmt_for_binlog.
    b) implies that we mustn't backup/restore auto_inc_intervals_forced.

    If there are more than 1 auto_increment columns, then intervals for
    different columns may mix into the
    auto_inc_intervals_in_cur_stmt_for_binlog list, which is logically wrong,
    but there is no point in preventing this mixing by preventing intervals
    from the secondly inserted column to come into the list, as such
    prevention would be wrong too.
    What will happen in the case of
    INSERT INTO t1 (auto_inc) VALUES(NULL);
    where t1 has a trigger which inserts into an auto_inc column of t2, is
    that in binlog we'll store the interval of t1 and the interval of t2 (when
    we store intervals, soon), then in slave, t1 will use both intervals, t2
    will use none; if t1 inserts the same number of rows as on master,
    normally the 2nd interval will not be used by t1, which is fine. t2's
    values will be wrong if t2's internal auto_increment counter is different
    from what it was on master (which is likely). In 5.1, in mixed binlogging
    mode, row-based binlogging is used for such cases where two
    auto_increment columns are inserted.
  */
  inline void record_first_successful_insert_id_in_cur_stmt(ulonglong id_arg)
  {
    if (first_successful_insert_id_in_cur_stmt == 0)
      first_successful_insert_id_in_cur_stmt= id_arg;
  }
  inline ulonglong read_first_successful_insert_id_in_prev_stmt(void)
  {
    if (!stmt_depends_on_first_successful_insert_id_in_prev_stmt)
    {
      /* It's the first time we read it */
      first_successful_insert_id_in_prev_stmt_for_binlog=
        first_successful_insert_id_in_prev_stmt;
      stmt_depends_on_first_successful_insert_id_in_prev_stmt= 1;
    }
    return first_successful_insert_id_in_prev_stmt;
  }
  /*
    Used by Intvar_log_event::do_apply_event() and by "SET INSERT_ID=#"
    (mysqlbinlog). We'll soon add a variant which can take many intervals in
    argument.
  */
  inline void force_one_auto_inc_interval(ulonglong next_id)
  {
    auto_inc_intervals_forced.empty(); // in case of multiple SET INSERT_ID
    auto_inc_intervals_forced.append(next_id, ULONGLONG_MAX, 0);
  }

  ulonglong  limit_found_rows;

private:
  longlong m_row_count_func;    /* For the ROW_COUNT() function */

public:
  inline longlong get_row_count_func() const
  {
    return m_row_count_func;
  }

  inline void set_row_count_func(longlong row_count_func)
  {
    m_row_count_func= row_count_func;
  }

  ha_rows    cuted_fields;

private:
  ha_rows m_sent_row_count;

  ha_rows m_examined_row_count;

private:
  USER_CONN *m_user_connect;

public:
  void set_user_connect(USER_CONN *uc);
  const USER_CONN* get_user_connect()
  { return m_user_connect; }

  void increment_user_connections_counter();
  void decrement_user_connections_counter();

  void increment_con_per_hour_counter();

  void increment_updates_counter();

  void increment_questions_counter();

  void time_out_user_resource_limits();

public:
  ha_rows get_sent_row_count() const
  { return m_sent_row_count; }

  ha_rows get_examined_row_count() const
  { return m_examined_row_count; }

  void set_sent_row_count(ha_rows count);
  void set_examined_row_count(ha_rows count);

  void inc_sent_row_count(ha_rows count);
  void inc_examined_row_count(ha_rows count);

  void inc_status_created_tmp_disk_tables();
  void inc_status_created_tmp_files();
  void inc_status_created_tmp_tables();
  void inc_status_select_full_join();
  void inc_status_select_full_range_join();
  void inc_status_select_range();
  void inc_status_select_range_check();
  void inc_status_select_scan();
  void inc_status_sort_merge_passes();
  void inc_status_sort_range();
  void inc_status_sort_rows(ha_rows count);
  void inc_status_sort_scan();
  void set_status_no_index_used();
  void set_status_no_good_index_used();

  const CHARSET_INFO *db_charset;
#if defined(ENABLED_PROFILING)
  PROFILING  profiling;
#endif

  sql_digest_state *m_digest;
  unsigned char *m_token_array;
  sql_digest_state m_digest_state;

  PSI_statement_locker *m_statement_psi;
#ifdef HAVE_PSI_STATEMENT_INTERFACE

  PSI_statement_locker_state m_statement_state;
#endif /* HAVE_PSI_STATEMENT_INTERFACE */

  PSI_idle_locker *m_idle_psi;
#ifdef HAVE_PSI_IDLE_INTERFACE

  PSI_idle_locker_state m_idle_state;
#endif /* HAVE_PSI_IDLE_INTERFACE */

  bool m_server_idle;

  /*
    Id of current query. Statement can be reused to execute several queries
    query_id is global in context of the whole MySQL server.
    ID is automatically generated from mutex-protected counter.
    It's used in handler code for various purposes: to check which columns
    from table are necessary for this select, to check if it's necessary to
    update auto-updatable fields (like auto_increment and timestamp).
  */
  query_id_t query_id;
  ulong      col_access;

  /* Statement id is thread-wide. This counter is used to generate ids */
  ulong      statement_id_counter;
  ulong      rand_saved_seed1, rand_saved_seed2;
  pthread_t  real_id;                           /* For debugging */
  my_thread_id  thread_id;
  uint       tmp_table;
  uint       server_status,open_options;
  enum enum_thread_type system_thread;
  uint       select_number;             //number of select (used for EXPLAIN)
  /*
    Current or next transaction isolation level.
    When a connection is established, the value is taken from
    @@session.tx_isolation (default transaction isolation for
    the session), which is in turn taken from @@global.tx_isolation
    (the global value).
    If there is no transaction started, this variable
    holds the value of the next transaction's isolation level.
    When a transaction starts, the value stored in this variable
    becomes "actual".
    At transaction commit or rollback, we assign this variable
    again from @@session.tx_isolation.
    The only statement that can otherwise change the value
    of this variable is SET TRANSACTION ISOLATION LEVEL.
    Its purpose is to effect the isolation level of the next
    transaction in this session. When this statement is executed,
    the value in this variable is changed. However, since
    this statement is only allowed when there is no active
    transaction, this assignment (naturally) only affects the
    upcoming transaction.
    At the end of the current active transaction the value is
    be reset again from @@session.tx_isolation, as described
    above.
  */
  enum_tx_isolation tx_isolation;
  /*
    Current or next transaction access mode.
    See comment above regarding tx_isolation.
  */
  bool              tx_read_only;
  enum_check_fields count_cuted_fields;

  DYNAMIC_ARRAY user_var_events;        /* For user variables replication */
  MEM_ROOT      *user_var_events_alloc; /* Allocate above array elements here */

  THD *next_to_commit;

  void set_trans_pos(const char *file, my_off_t pos)
  {
    DBUG_ENTER("THD::set_trans_pos");
    DBUG_ASSERT(((file == 0) && (pos == 0)) || ((file != 0) && (pos != 0)));
    if (file)
    {
      DBUG_PRINT("enter", ("file: %s, pos: %llu", file, pos));
      // Only the file name should be used, not the full path
      m_trans_log_file= file + dirname_length(file);
      if (!m_trans_fixed_log_file)
        m_trans_fixed_log_file= (char*) alloc_root(&main_mem_root, FN_REFLEN+1);
      DBUG_ASSERT(strlen(m_trans_log_file) <= FN_REFLEN);
      strcpy(m_trans_fixed_log_file, m_trans_log_file);
    }
    else
    {
      m_trans_log_file= NULL;
      m_trans_fixed_log_file= NULL;
    }

    m_trans_end_pos= pos;
    DBUG_PRINT("return", ("m_trans_log_file: %s, m_trans_fixed_log_file: %s, "
                          "m_trans_end_pos: %llu", m_trans_log_file,
                          m_trans_fixed_log_file, m_trans_end_pos));
    DBUG_VOID_RETURN;
  }

  void get_trans_pos(const char **file_var, my_off_t *pos_var) const
  {
    DBUG_ENTER("THD::get_trans_pos");
    if (file_var)
      *file_var = m_trans_log_file;
    if (pos_var)
      *pos_var= m_trans_end_pos;
    DBUG_PRINT("return", ("file: %s, pos: %llu",
                          file_var ? *file_var : "<none>",
                          pos_var ? *pos_var : 0));
    DBUG_VOID_RETURN;
  }

  void get_trans_fixed_pos(const char **file_var, my_off_t *pos_var) const
  {
    DBUG_ENTER("THD::get_trans_fixed_pos");
    if (file_var)
      *file_var = m_trans_fixed_log_file;
    if (pos_var)
      *pos_var= m_trans_end_pos;
    DBUG_PRINT("return", ("file: %s, pos: %llu",
                          file_var ? *file_var : "<none>",
                          pos_var ? *pos_var : 0));
    DBUG_VOID_RETURN;
  }
  /*
    Error code from committing or rolling back the transaction.
  */
  enum Commit_error
  {
    CE_NONE= 0,
    CE_FLUSH_ERROR,
    CE_COMMIT_ERROR,
    CE_ERROR_COUNT
  } commit_error;

  /*
    Define durability properties that engines may check to
    improve performance.
  */
  enum durability_properties durability_property;

  /*
    If checking this in conjunction with a wait condition, please
    include a check after enter_cond() if you want to avoid a race
    condition. For details see the implementation of awake(),
    especially the "broadcast" part.
  */
  enum killed_state
  {
    NOT_KILLED=0,
    KILL_BAD_DATA=1,
    KILL_CONNECTION=ER_SERVER_SHUTDOWN,
    KILL_QUERY=ER_QUERY_INTERRUPTED,
    KILLED_NO_VALUE      /* means neither of the states */
  };
  killed_state volatile killed;

  /* scramble - random string sent to client on handshake */
  char       scramble[SCRAMBLE_LENGTH+1];

  bool       slave_thread, one_shot_set;
  bool       no_errors;
  uchar      password;
  bool is_fatal_error;
  bool       transaction_rollback_request;
  bool       is_fatal_sub_stmt_error;
  bool       query_start_used, query_start_usec_used;
  bool       rand_used, time_zone_used;
  /* for IS NULL => = last_insert_id() fix in remove_eq_conds() */
  bool       substitute_null_with_insert_id;
  bool       in_lock_tables;
  bool       is_slave_error;
  bool       bootstrap;

  bool       thread_specific_used;
  bool       charset_is_system_charset, charset_is_collation_connection;
  bool       charset_is_character_set_filesystem;
  bool       enable_slow_log;   /* enable slow log for current statement */
  bool       abort_on_warning;
  bool       got_warning;       /* Set on call to push_warning() */
  /* set during loop of derived table processing */
  bool       derived_tables_processing;
  my_bool    tablespace_op;     /* This is TRUE in DISCARD/IMPORT TABLESPACE */

  sp_rcontext *sp_runtime_ctx;
  sp_cache   *sp_proc_cache;
  sp_cache   *sp_func_cache;

  uint       query_name_consts;

  /*
    If we do a purge of binary logs, log index info of the threads
    that are currently reading it needs to be adjusted. To do that
    each thread that is using LOG_INFO needs to adjust the pointer to it
  */
  LOG_INFO*  current_linfo;
  NET*       slave_net;                 // network connection from slave -> m.
  /* Used by the sys_var class to store temporary values */
  union
  {
    my_bool   my_bool_value;
    long      long_value;
    ulong     ulong_value;
    ulonglong ulonglong_value;
    double    double_value;
  } sys_var_tmp;
  
  struct {
    /* 
      If true, mysql_bin_log::write(Log_event) call will not write events to 
      binlog, and maintain 2 below variables instead (use
      mysql_bin_log.start_union_events to turn this on)
    */
    bool do_union;
    /*
      If TRUE, at least one mysql_bin_log::write(Log_event) call has been
      made after last mysql_bin_log.start_union_events() call.
    */
    bool unioned_events;
    /*
      If TRUE, at least one mysql_bin_log::write(Log_event e), where 
      e.cache_stmt == TRUE call has been made after last 
      mysql_bin_log.start_union_events() call.
    */
    bool unioned_events_trans;
    
    /* 
      'queries' (actually SP statements) that run under inside this binlog
      union have thd->query_id >= first_query_id.
    */
    query_id_t first_query_id;
  } binlog_evt_union;

  Parser_state *m_parser_state;

  Locked_tables_list locked_tables_list;

#ifdef WITH_PARTITION_STORAGE_ENGINE
  partition_info *work_part_info;
#endif

#ifndef EMBEDDED_LIBRARY

  DYNAMIC_ARRAY audit_class_plugins;
  unsigned long audit_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
#endif

#if defined(ENABLED_DEBUG_SYNC)
  /* Debug Sync facility. See debug_sync.cc. */
  struct st_debug_sync_control *debug_sync_control;
#endif /* defined(ENABLED_DEBUG_SYNC) */

  // We don't want to load/unload plugins for unit tests.
  bool m_enable_plugins;

  THD(bool enable_plugins= true);

  /*
    The THD dtor is effectively split in two:
      THD::release_resources() and ~THD().

    We want to minimize the time we hold LOCK_thread_count,
    so when destroying a global thread, do:

    thd->release_resources()
    remove_global_thread(thd);
    delete thd;
   */
  ~THD();

  void release_resources();
  bool release_resources_done() const { return m_release_resources_done; }

private:
  bool m_release_resources_done;
  bool cleanup_done;
  void cleanup(void);

public:
  void init(void);
  /*
    Initialize memory roots necessary for query processing and (!)
    pre-allocate memory for it. We can't do that in THD constructor because
    there are use cases (acl_init, delayed inserts, watcher threads,
    killing mysqld) where it's vital to not allocate excessive and not used
    memory. Note, that we still don't return error from init_for_queries():
    if preallocation fails, we should notice that at the first call to
    alloc_root. 
  */
  void init_for_queries(Relay_log_info *rli= NULL);
  void change_user(void);
  void cleanup_after_query();
  bool store_globals();
  bool restore_globals();
#ifdef SIGNAL_WITH_VIO_SHUTDOWN
  inline void set_active_vio(Vio* vio)
  {
    mysql_mutex_lock(&LOCK_thd_data);
    active_vio = vio;
    mysql_mutex_unlock(&LOCK_thd_data);
  }
  inline void clear_active_vio()
  {
    mysql_mutex_lock(&LOCK_thd_data);
    active_vio = 0;
    mysql_mutex_unlock(&LOCK_thd_data);
  }
  void shutdown_active_vio();
#endif
  void awake(THD::killed_state state_to_set);

  void disconnect();

#ifndef MYSQL_CLIENT
  enum enum_binlog_query_type {
    /* The query can be logged in row format or in statement format. */
    ROW_QUERY_TYPE,
    
    /* The query has to be logged in statement format. */
    STMT_QUERY_TYPE,
    
    QUERY_TYPE_COUNT
  };
  
  int binlog_query(enum_binlog_query_type qtype,
                   char const *query, ulong query_len, bool is_trans,
                   bool direct, bool suppress_use,
                   int errcode);
#endif

  // Begin implementation of MDL_context_owner interface.

  inline void
  enter_cond(mysql_cond_t *cond, mysql_mutex_t* mutex,
             const PSI_stage_info *stage, PSI_stage_info *old_stage,
             const char *src_function, const char *src_file,
             int src_line)
  {
    DBUG_ENTER("THD::enter_cond");
    mysql_mutex_assert_owner(mutex);
    DBUG_PRINT("debug", ("thd: 0x%llx, mysys_var: 0x%llx, current_mutex: 0x%llx -> 0x%llx",
                         (ulonglong) this,
                         (ulonglong) mysys_var,
                         (ulonglong) mysys_var->current_mutex,
                         (ulonglong) mutex));
    mysys_var->current_mutex = mutex;
    mysys_var->current_cond = cond;
    enter_stage(stage, old_stage, src_function, src_file, src_line);
    DBUG_VOID_RETURN;
  }
  inline void exit_cond(const PSI_stage_info *stage,
                        const char *src_function, const char *src_file,
                        int src_line)
  {
    DBUG_ENTER("THD::exit_cond");
    /*
      Putting the mutex unlock in thd->exit_cond() ensures that
      mysys_var->current_mutex is always unlocked _before_ mysys_var->mutex is
      locked (if that would not be the case, you'll get a deadlock if someone
      does a THD::awake() on you).
    */
    DBUG_PRINT("debug", ("thd: 0x%llx, mysys_var: 0x%llx, current_mutex: 0x%llx -> 0x%llx",
                         (ulonglong) this,
                         (ulonglong) mysys_var,
                         (ulonglong) mysys_var->current_mutex,
                         0ULL));
    mysql_mutex_unlock(mysys_var->current_mutex);
    mysql_mutex_lock(&mysys_var->mutex);
    mysys_var->current_mutex = 0;
    mysys_var->current_cond = 0;
    enter_stage(stage, NULL, src_function, src_file, src_line);
    mysql_mutex_unlock(&mysys_var->mutex);
    DBUG_VOID_RETURN;
  }

  virtual int is_killed() { return killed; }
  virtual THD* get_thd() { return this; }

  virtual bool notify_shared_lock(MDL_context_owner *ctx_in_use,
                                  bool needs_thr_lock_abort);

  // End implementation of MDL_context_owner interface.

  inline sql_mode_t datetime_flags() const
  {
    return variables.sql_mode &
      (MODE_NO_ZERO_IN_DATE | MODE_NO_ZERO_DATE | MODE_INVALID_DATES);
  }
  inline bool is_strict_mode() const
  {
    return MY_TEST(variables.sql_mode & (MODE_STRICT_TRANS_TABLES |
                                         MODE_STRICT_ALL_TABLES));
  }
  inline Time_zone *time_zone()
  {
    time_zone_used= 1;
    return variables.time_zone;
  }
  inline time_t query_start()
  {
    query_start_used= 1;
    return start_time.tv_sec;
  }
  inline long query_start_usec()
  {
    query_start_usec_used= 1;
    return start_time.tv_usec;
  }
  inline timeval query_start_timeval()
  {
    query_start_used= query_start_usec_used= true;
    return start_time;
  }
  timeval query_start_timeval_trunc(uint decimals);
  inline void set_time()
  {
    start_utime= utime_after_lock= my_micro_time();
    if (user_time.tv_sec || user_time.tv_usec)
    {
      start_time= user_time;
    }
    else
      my_micro_time_to_timeval(start_utime, &start_time);

#ifdef HAVE_PSI_THREAD_INTERFACE
    PSI_THREAD_CALL(set_thread_start_time)(start_time.tv_sec);
#endif
  }
  inline void set_current_time()
  {
    my_micro_time_to_timeval(my_micro_time(), &start_time);
#ifdef HAVE_PSI_THREAD_INTERFACE
    PSI_THREAD_CALL(set_thread_start_time)(start_time.tv_sec);
#endif
  }
  inline void set_time(const struct timeval *t)
  {
    start_time= user_time= *t;
    start_utime= utime_after_lock= my_micro_time();
#ifdef HAVE_PSI_THREAD_INTERFACE
    PSI_THREAD_CALL(set_thread_start_time)(start_time.tv_sec);
#endif
  }
  /*TODO: this will be obsolete when we have support for 64 bit my_time_t */
  inline bool   is_valid_time() 
  { 
    return (IS_TIME_T_VALID_FOR_TIMESTAMP(start_time.tv_sec));
  }
  void set_time_after_lock()
  {
    utime_after_lock= my_micro_time();
    MYSQL_SET_STATEMENT_LOCK_TIME(m_statement_psi, (utime_after_lock - start_utime));
  }
  ulonglong current_utime()  { return my_micro_time(); }
  void update_server_status()
  {
    ulonglong end_utime_of_query= current_utime();
    if (end_utime_of_query > utime_after_lock + variables.long_query_time)
      server_status|= SERVER_QUERY_WAS_SLOW;
  }
  inline ulonglong found_rows(void)
  {
    return limit_found_rows;
  }
  inline bool in_multi_stmt_transaction_mode() const
  {
    return variables.option_bits & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN);
  }
  inline bool in_active_multi_stmt_transaction() const
  {
    return server_status & SERVER_STATUS_IN_TRANS;
  }
  inline bool fill_derived_tables()
  {
    return !stmt_arena->is_stmt_prepare() && !lex->only_view_structure();
  }
  inline bool fill_information_schema_tables()
  {
    return !stmt_arena->is_stmt_prepare();
  }
  inline void* trans_alloc(unsigned int size)
  {
    return alloc_root(&transaction.mem_root,size);
  }

  LEX_STRING *make_lex_string(LEX_STRING *lex_str,
                              const char* str, uint length,
                              bool allocate_lex_string);

  bool convert_string(LEX_STRING *to, const CHARSET_INFO *to_cs,
                      const char *from, uint from_length,
                      const CHARSET_INFO *from_cs);

  bool convert_string(String *s, const CHARSET_INFO *from_cs,
                      const CHARSET_INFO *to_cs);

  void add_changed_table(TABLE *table);
  void add_changed_table(const char *key, long key_length);
  CHANGED_TABLE_LIST * changed_table_dup(const char *key, long key_length);
  int send_explain_fields(select_result *result);

  inline void clear_error()
  {
    DBUG_ENTER("clear_error");
    if (get_stmt_da()->is_error())
      get_stmt_da()->reset_diagnostics_area();
    is_slave_error= 0;
    DBUG_VOID_RETURN;
  }
#ifndef EMBEDDED_LIBRARY
  inline bool vio_ok() const { return net.vio != 0; }
  bool is_connected()
  {
    /*
      All system threads (e.g., the slave IO thread) are connected but
      not using vio. So this function always returns true for all
      system threads.
    */
    return system_thread || (vio_ok() ? vio_is_connected(net.vio) : FALSE);
  }
#else
  inline bool vio_ok() const { return TRUE; }
  inline bool is_connected() { return TRUE; }
#endif

  inline void fatal_error()
  {
    DBUG_ASSERT(get_stmt_da()->is_error() || killed);
    is_fatal_error= 1;
    DBUG_PRINT("error",("Fatal error set"));
  }
  inline bool is_error() const { return get_stmt_da()->is_error(); }

  Diagnostics_area *get_stmt_da()
  { return m_stmt_da; }

  const Diagnostics_area *get_stmt_da() const
  { return m_stmt_da; }

  void set_stmt_da(Diagnostics_area *da)
  { m_stmt_da= da; }

public:
  inline const CHARSET_INFO *charset()
  { return variables.character_set_client; }
  void update_charset();

  void change_item_tree(Item **place, Item *new_value)
  {
    /* TODO: check for OOM condition here */
    if (!stmt_arena->is_conventional())
    {
      DBUG_PRINT("info",
                 ("change_item_tree place %p old_value %p new_value %p",
                  place, *place, new_value));
      if (new_value)
        new_value->set_runtime_created(); /* Note the change of item tree */
      nocheck_register_item_tree_change(place, *place, mem_root);
    }
    *place= new_value;
  }

/*
  Find and update change record of an underlying item.

  @param old_ref The old place of moved expression.
  @param new_ref The new place of moved expression.
  @details
  During permanent transformations, e.g. join flattening in simplify_joins,
  a condition could be moved from one place to another, e.g. from on_expr
  to WHERE condition. If the moved condition has replaced some other with
  change_item_tree() function, the change record will restore old value
  to the wrong place during rollback_item_tree_changes. This function goes
  through the list of change records, and replaces Item_change_record::place.
*/
  void change_item_tree_place(Item **old_ref, Item **new_ref);
  void nocheck_register_item_tree_change(Item **place, Item *old_value,
                                         MEM_ROOT *runtime_memroot);
  void rollback_item_tree_changes();

  /*
    Cleanup statement parse state (parse tree, lex) and execution
    state after execution of a non-prepared SQL statement.
  */
  void end_statement();
  inline int killed_errno() const
  {
    killed_state killed_val; /* to cache the volatile 'killed' */
    return (killed_val= killed) != KILL_BAD_DATA ? killed_val : 0;
  }
  inline void send_kill_message() const
  {
    int err= killed_errno();
    if (err && !get_stmt_da()->is_set())
    {
      if ((err == KILL_CONNECTION) && !shutdown_in_progress)
        err = KILL_QUERY;
      /*
        KILL is fatal because:
        - if a condition handler was allowed to trap and ignore a KILL, one
        could create routines which the DBA could not kill
        - INSERT/UPDATE IGNORE should fail: if KILL arrives during
        JOIN::optimize(), statement cannot possibly run as its caller expected
        => "OK" would be misleading the caller.
      */
      my_message(err, ER(err), MYF(ME_FATALERROR));
    }
  }
  /* return TRUE if we will abort query if we make a warning now */
  inline bool really_abort_on_warning()
  {
    return (abort_on_warning &&
            (!transaction.stmt.cannot_safely_rollback() ||
             (variables.sql_mode & MODE_STRICT_ALL_TABLES)));
  }
  void set_status_var_init();
  void reset_n_backup_open_tables_state(Open_tables_backup *backup);
  void restore_backup_open_tables_state(Open_tables_backup *backup);
  void reset_sub_statement_state(Sub_statement_state *backup, uint new_state);
  void restore_sub_statement_state(Sub_statement_state *backup);
  void set_n_backup_active_arena(Query_arena *set, Query_arena *backup);
  void restore_active_arena(Query_arena *set, Query_arena *backup);

  /*
    @todo Make these methods private or remove them completely.  Only
    decide_logging_format should call them. /Sven
  */
  inline void set_current_stmt_binlog_format_row_if_mixed()
  {
    DBUG_ENTER("set_current_stmt_binlog_format_row_if_mixed");
    /*
      This should only be called from decide_logging_format.

      @todo Once we have ensured this, uncomment the following
      statement, remove the big comment below that, and remove the
      in_sub_stmt==0 condition from the following 'if'.
    */
    /* DBUG_ASSERT(in_sub_stmt == 0); */
    /*
      If in a stored/function trigger, the caller should already have done the
      change. We test in_sub_stmt to prevent introducing bugs where people
      wouldn't ensure that, and would switch to row-based mode in the middle
      of executing a stored function/trigger (which is too late, see also
      reset_current_stmt_binlog_format_row()); this condition will make their
      tests fail and so force them to propagate the
      lex->binlog_row_based_if_mixed upwards to the caller.
    */
    if ((variables.binlog_format == BINLOG_FORMAT_MIXED) &&
        (in_sub_stmt == 0))
      set_current_stmt_binlog_format_row();

    DBUG_VOID_RETURN;
  }
  inline void set_current_stmt_binlog_format_row()
  {
    DBUG_ENTER("set_current_stmt_binlog_format_row");
    current_stmt_binlog_format= BINLOG_FORMAT_ROW;
    DBUG_VOID_RETURN;
  }
  inline void clear_current_stmt_binlog_format_row()
  {
    DBUG_ENTER("clear_current_stmt_binlog_format_row");
    current_stmt_binlog_format= BINLOG_FORMAT_STMT;
    DBUG_VOID_RETURN;
  }
  inline void reset_current_stmt_binlog_format_row()
  {
    DBUG_ENTER("reset_current_stmt_binlog_format_row");
    /*
      If there are temporary tables, don't reset back to
      statement-based. Indeed it could be that:
      CREATE TEMPORARY TABLE t SELECT UUID(); # row-based
      # and row-based does not store updates to temp tables
      # in the binlog.
      INSERT INTO u SELECT * FROM t; # stmt-based
      and then the INSERT will fail as data inserted into t was not logged.
      So we continue with row-based until the temp table is dropped.
      If we are in a stored function or trigger, we mustn't reset in the
      middle of its execution (as the binary logging way of a stored function
      or trigger is decided when it starts executing, depending for example on
      the caller (for a stored function: if caller is SELECT or
      INSERT/UPDATE/DELETE...).
    */
    DBUG_PRINT("debug",
               ("temporary_tables: %s, in_sub_stmt: %s, system_thread: %s",
                YESNO(temporary_tables), YESNO(in_sub_stmt),
                show_system_thread(system_thread)));
    if (in_sub_stmt == 0)
    {
      if (variables.binlog_format == BINLOG_FORMAT_ROW)
        set_current_stmt_binlog_format_row();
      else if (temporary_tables == NULL)
        clear_current_stmt_binlog_format_row();
    }
    DBUG_VOID_RETURN;
  }

  Gtid_set *get_gtid_next_list()
  {
    return variables.gtid_next_list.is_non_null ?
      variables.gtid_next_list.gtid_set : NULL;
  }

  const Gtid_set *get_gtid_next_list_const() const
  {
    return const_cast<THD *>(this)->get_gtid_next_list();
  }

  Group_cache *get_group_cache(bool is_transactional);

  Gtid owned_gtid;
  Gtid_set owned_gtid_set;

  void clear_owned_gtids()
  {
    if (owned_gtid.sidno == -1)
    {
#ifdef HAVE_GTID_NEXT_LIST
      owned_gtid_set.clear();
#else
      DBUG_ASSERT(0);
#endif
    }
    owned_gtid.sidno= 0;
  }

  /*
    There are some statements (like OPTIMIZE TABLE, ANALYZE TABLE and
    REPAIR TABLE) that might call trans_rollback_stmt() and also will be
    sucessfully executed and will have to go to the binary log.
    For these statements, the skip_gtid_rollback flag must be set to avoid
    problems when the statement is executed with a GTID_NEXT set to GTID_GROUP
    (like the SQL thread do when applying events from other server).
    When this flag is set, a call to gtid_rollback() will do nothing.
  */
  bool skip_gtid_rollback;

  bool set_db(const char *new_db, size_t new_db_len)
  {
    bool result;
    /*
      Acquiring mutex LOCK_thd_data as we either free the memory allocated
      for the database and reallocating the memory for the new db or memcpy
      the new_db to the db.
    */
    mysql_mutex_lock(&LOCK_thd_data);
    /* Do not reallocate memory if current chunk is big enough. */
    if (db && new_db && db_length >= new_db_len)
      memcpy(db, new_db, new_db_len+1);
    else
    {
      my_free(db);
      if (new_db)
        db= my_strndup(new_db, new_db_len, MYF(MY_WME | ME_FATALERROR));
      else
        db= NULL;
    }
    db_length= db ? new_db_len : 0;
    mysql_mutex_unlock(&LOCK_thd_data);
    result= new_db && !db;
#ifdef HAVE_PSI_THREAD_INTERFACE
    if (result)
      PSI_THREAD_CALL(set_thread_db)(new_db, static_cast<int>(new_db_len));
#endif
    return result;
  }

  void reset_db(char *new_db, size_t new_db_len)
  {
    db= new_db;
    db_length= new_db_len;
#ifdef HAVE_PSI_THREAD_INTERFACE
    PSI_THREAD_CALL(set_thread_db)(new_db, static_cast<int>(new_db_len));
#endif
  }
  /*
    Copy the current database to the argument. Use the current arena to
    allocate memory for a deep copy: current database may be freed after
    a statement is parsed but before it's executed.
  */
  bool copy_db_to(char **p_db, size_t *p_db_length)
  {
    if (db == NULL)
    {
      my_message(ER_NO_DB_ERROR, ER(ER_NO_DB_ERROR), MYF(0));
      return TRUE;
    }
    *p_db= strmake(db, db_length);
    *p_db_length= db_length;
    return FALSE;
  }
  thd_scheduler scheduler;

public:
  inline Internal_error_handler *get_internal_handler()
  { return m_internal_handler; }

  void push_internal_handler(Internal_error_handler *handler);

private:
  bool handle_condition(uint sql_errno,
                        const char* sqlstate,
                        Sql_condition::enum_warning_level level,
                        const char* msg,
                        Sql_condition ** cond_hdl);

public:
  Internal_error_handler *pop_internal_handler();

  Opt_trace_context opt_trace; 

  void raise_error(uint code);

  void raise_error_printf(uint code, ...);

  void raise_warning(uint code);

  void raise_warning_printf(uint code, ...);

  void raise_note(uint code);

  void raise_note_printf(uint code, ...);

private:
  /*
    Only the implementation of the SIGNAL and RESIGNAL statements
    is permitted to raise SQL conditions in a generic way,
    or to raise them by bypassing handlers (RESIGNAL).
    To raise a SQL condition, the code should use the public
    raise_error() or raise_warning() methods provided by class THD.
  */
  friend class Sql_cmd_common_signal;
  friend class Sql_cmd_signal;
  friend class Sql_cmd_resignal;
  friend void push_warning(THD*, Sql_condition::enum_warning_level, uint, const char*);
  friend void my_message_sql(uint, const char *, myf);

  Sql_condition*
  raise_condition(uint sql_errno,
                  const char* sqlstate,
                  Sql_condition::enum_warning_level level,
                  const char* msg);

public:
  virtual void set_statement(Statement *stmt);

  void set_command(enum enum_server_command command);

  inline enum enum_server_command get_command() const
  { return m_command; }

  void set_query(char *query_arg, uint32 query_length_arg,
                 const CHARSET_INFO *cs_arg)
  {
    set_query(CSET_STRING(query_arg, query_length_arg, cs_arg));
  }
  void set_query(char *query_arg, uint32 query_length_arg) /*Mutex protected*/
  {
    set_query(CSET_STRING(query_arg, query_length_arg, charset()));
  }
  void set_query(const CSET_STRING &str); /* Mutex protected */
  void reset_query()               /* Mutex protected */
  { set_query(CSET_STRING()); }
  void set_query_and_id(char *query_arg, uint32 query_length_arg,
                        const CHARSET_INFO *cs, query_id_t new_query_id);
  void set_query_id(query_id_t new_query_id);
  void set_open_tables(TABLE *open_tables_arg)
  {
    mysql_mutex_lock(&LOCK_thd_data);
    open_tables= open_tables_arg;
    mysql_mutex_unlock(&LOCK_thd_data);
  }
  void set_mysys_var(struct st_my_thread_var *new_mysys_var);
  void enter_locked_tables_mode(enum_locked_tables_mode mode_arg)
  {
    DBUG_ASSERT(locked_tables_mode == LTM_NONE);

    if (mode_arg == LTM_LOCK_TABLES)
    {
      /*
        When entering LOCK TABLES mode we should set explicit duration
        for all metadata locks acquired so far in order to avoid releasing
        them till UNLOCK TABLES statement.
        We don't do this when entering prelocked mode since sub-statements
        don't release metadata locks and restoring status-quo after leaving
        prelocking mode gets complicated.
      */
      mdl_context.set_explicit_duration_for_all_locks();
    }

    locked_tables_mode= mode_arg;
  }
  void leave_locked_tables_mode();
  int decide_logging_format(TABLE_LIST *tables);
  bool
  is_dml_gtid_compatible(bool transactional_table,
                         bool non_transactional_table,
                         bool non_transactional_tmp_tables) const;
  bool is_ddl_gtid_compatible() const;
  void binlog_invoker() { m_binlog_invoker= TRUE; }
  bool need_binlog_invoker() { return m_binlog_invoker; }
  void get_definer(LEX_USER *definer);
  void set_invoker(const LEX_STRING *user, const LEX_STRING *host)
  {
    invoker_user= *user;
    invoker_host= *host;
  }
  LEX_STRING get_invoker_user() { return invoker_user; }
  LEX_STRING get_invoker_host() { return invoker_host; }
  bool has_invoker() { return invoker_user.str != NULL; }

  void mark_transaction_to_rollback(bool all);

#ifndef DBUG_OFF
private:
  int gis_debug; // Storage for "SELECT ST_GIS_DEBUG(param);"
public:
  int get_gis_debug() { return gis_debug; }
  void set_gis_debug(int arg) { gis_debug= arg; }
#endif

private:

  Internal_error_handler *m_internal_handler;

  LEX main_lex;
  MEM_ROOT main_mem_root;
  Diagnostics_area main_da;
  Diagnostics_area *m_stmt_da;

  bool m_binlog_invoker;

  LEX_STRING invoker_user;
  LEX_STRING invoker_host;
public:
  bool duplicate_slave_uuid;
};


class Prepared_stmt_arena_holder
{
public:
  Prepared_stmt_arena_holder(THD *thd, bool activate_now_if_needed= true)
   :m_thd(thd),
    m_arena(NULL)
  {
    if (activate_now_if_needed &&
        !m_thd->stmt_arena->is_conventional() &&
        m_thd->mem_root != m_thd->stmt_arena->mem_root)
    {
      m_thd->set_n_backup_active_arena(m_thd->stmt_arena, &m_backup);
      m_arena= m_thd->stmt_arena;
    }
  }

  ~Prepared_stmt_arena_holder()
  {
    if (is_activated())
      m_thd->restore_active_arena(m_arena, &m_backup);
  }

  bool is_activated() const
  { return m_arena != NULL; }

private:
  THD *const m_thd;

  Query_arena *m_arena;

  Query_arena m_backup;
};


inline void
my_ok(THD *thd, ulonglong affected_rows= 0, ulonglong id= 0,
        const char *message= NULL)
{
  thd->set_row_count_func(affected_rows);
  thd->get_stmt_da()->set_ok_status(affected_rows, id, message);
}


inline void
my_eof(THD *thd)
{
  thd->set_row_count_func(-1);
  thd->get_stmt_da()->set_eof_status(thd);
}

#define tmp_disable_binlog(A)       \
  {ulonglong tmp_disable_binlog__save_options= (A)->variables.option_bits; \
  (A)->variables.option_bits&= ~OPTION_BIN_LOG

#define reenable_binlog(A)   (A)->variables.option_bits= tmp_disable_binlog__save_options;}


LEX_STRING *
make_lex_string_root(MEM_ROOT *mem_root,
                     LEX_STRING *lex_str, const char* str, uint length,
                     bool allocate_lex_string);

/*
  Used to hold information about file and file structure in exchange
  via non-DB file (...INTO OUTFILE..., ...LOAD DATA...)
  XXX: We never call destructor for objects of this class.
*/

class sql_exchange :public Sql_alloc
{
public:
  enum enum_filetype filetype; /* load XML, Added by Arnold & Erik */
  char *file_name;
  const String *field_term, *enclosed, *line_term, *line_start, *escaped;
  bool opt_enclosed;
  bool dumpfile;
  ulong skip_lines;
  const CHARSET_INFO *cs;
  sql_exchange(char *name, bool dumpfile_flag,
               enum_filetype filetype_arg= FILETYPE_CSV);
  bool escaped_given(void);
};

/*
  This is used to get result from a select
*/

class JOIN;

class select_result :public Sql_alloc {
protected:
  THD *thd;
  SELECT_LEX_UNIT *unit;
public:
  ha_rows estimated_rowcount;
  select_result();
  virtual ~select_result() {};
  virtual int prepare(List<Item> &list, SELECT_LEX_UNIT *u)
  {
    unit= u;
    return 0;
  }
  virtual int prepare2(void) { return 0; }
  /*
    Because of peculiarities of prepared statements protocol
    we need to know number of columns in the result set (if
    there is a result set) apart from sending columns metadata.
  */
  virtual uint field_count(List<Item> &fields) const
  { return fields.elements; }
  virtual bool send_result_set_metadata(List<Item> &list, uint flags)=0;
  virtual bool send_data(List<Item> &items)=0;
  virtual bool initialize_tables (JOIN *join=0) { return 0; }
  virtual void send_error(uint errcode,const char *err);
  virtual bool send_eof()=0;
  virtual bool check_simple_select() const;
  virtual void abort_result_set() {}
  /*
    Cleanup instance of this class for next execution of a prepared
    statement/stored procedure.
  */
  virtual void cleanup();
  void set_thd(THD *thd_arg) { thd= thd_arg; }

  void reset_offset_limit_cnt() { unit->offset_limit_cnt= 0; }

#ifdef EMBEDDED_LIBRARY
  virtual void begin_dataset() {}
#else
  void begin_dataset() {}
#endif
};


/*
  Base class for select_result descendands which intercept and
  transform result set rows. As the rows are not sent to the client,
  sending of result set metadata should be suppressed as well.
*/

class select_result_interceptor: public select_result
{
public:
  select_result_interceptor() {}              /* Remove gcc warning */
  uint field_count(List<Item> &fields) const { return 0; }
  bool send_result_set_metadata(List<Item> &fields, uint flag) { return FALSE; }
};


class select_send :public select_result {
  bool is_result_set_started;
public:
  select_send() :is_result_set_started(FALSE) {}
  bool send_result_set_metadata(List<Item> &list, uint flags);
  bool send_data(List<Item> &items);
  bool send_eof();
  virtual bool check_simple_select() const { return FALSE; }
  void abort_result_set();
  virtual void cleanup();
};


class select_to_file :public select_result_interceptor {
protected:
  sql_exchange *exchange;
  File file;
  IO_CACHE cache;
  ha_rows row_count;
  char path[FN_REFLEN];

public:
  select_to_file(sql_exchange *ex) :exchange(ex), file(-1),row_count(0L)
  { path[0]=0; }
  ~select_to_file();
  void send_error(uint errcode,const char *err);
  bool send_eof();
  void cleanup();
};


#define ESCAPE_CHARS "ntrb0ZN" // keep synchronous with READ_INFO::unescape


/*
 List of all possible characters of a numeric value text representation.
*/
#define NUMERIC_CHARS ".0123456789e+-"


class select_export :public select_to_file {
  uint field_term_length;
  int field_sep_char,escape_char,line_sep_char;
  int field_term_char; // first char of FIELDS TERMINATED BY or MAX_INT
  /*
    The is_ambiguous_field_sep field is true if a value of the field_sep_char
    field is one of the 'n', 't', 'r' etc characters
    (see the READ_INFO::unescape method and the ESCAPE_CHARS constant value).
  */
  bool is_ambiguous_field_sep;
  /*
     The is_ambiguous_field_term is true if field_sep_char contains the first
     char of the FIELDS TERMINATED BY (ENCLOSED BY is empty), and items can
     contain this character.
  */
  bool is_ambiguous_field_term;
  /*
    The is_unsafe_field_sep field is true if a value of the field_sep_char
    field is one of the '0'..'9', '+', '-', '.' and 'e' characters
    (see the NUMERIC_CHARS constant value).
  */
  bool is_unsafe_field_sep;
  bool fixed_row_size;
  const CHARSET_INFO *write_cs; // output charset
public:
  select_export(sql_exchange *ex) :select_to_file(ex) {}
  ~select_export();
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
};


class select_dump :public select_to_file {
public:
  select_dump(sql_exchange *ex) :select_to_file(ex) {}
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
};

class select_insert :public select_result_interceptor {
public:
  TABLE_LIST *table_list;
  TABLE *table;
private:
  List<Item> *fields;
protected:
  bool bulk_insert_started;
public:
  ulonglong autoinc_value_of_last_inserted_row; // autogenerated or not
  COPY_INFO info;
  COPY_INFO update; 
  bool insert_into_view;

  select_insert(TABLE_LIST *table_list_par,
                TABLE *table_par,
                List<Item> *target_columns,
                List<Item> *target_or_source_columns,
                List<Item> *update_fields,
                List<Item> *update_values,
                enum_duplicates duplic,
                bool ignore)
    :table_list(table_list_par),
     table(table_par),
     fields(target_or_source_columns),
     bulk_insert_started(false),
     autoinc_value_of_last_inserted_row(0),
     info(COPY_INFO::INSERT_OPERATION,
          target_columns,
          // manage_defaults
          (target_columns == NULL || target_columns->elements != 0),
          duplic,
          ignore),
     update(COPY_INFO::UPDATE_OPERATION,
            update_fields,
            update_values),
     insert_into_view(table_list_par && table_list_par->view != 0)
  {
    DBUG_ASSERT(target_or_source_columns != NULL);
    DBUG_ASSERT(target_columns == target_or_source_columns ||
                target_columns == NULL);
  }


public:
  ~select_insert();
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  virtual int prepare2(void);
  bool send_data(List<Item> &items);
  virtual void store_values(List<Item> &values);
  void send_error(uint errcode,const char *err);
  bool send_eof();
  virtual void abort_result_set();
  /* not implemented: select_insert is never re-used in prepared statements */
  void cleanup();
};


class select_create: public select_insert {
  ORDER *group;
  TABLE_LIST *create_table;
  HA_CREATE_INFO *create_info;
  TABLE_LIST *select_tables;
  Alter_info *alter_info;
  Field **field;
  /* lock data for tmp table */
  MYSQL_LOCK *m_lock;
  /* m_lock or thd->extra_lock */
  MYSQL_LOCK **m_plock;
public:
  select_create (TABLE_LIST *table_arg,
                 HA_CREATE_INFO *create_info_par,
                 Alter_info *alter_info_arg,
                 List<Item> &select_fields,enum_duplicates duplic, bool ignore,
                 TABLE_LIST *select_tables_arg)
    :select_insert (NULL, // table_list_par
                    NULL, // table_par
                    NULL, // target_columns
                    &select_fields,
                    NULL, // update_fields
                    NULL, // update_values
                    duplic,
                    ignore),
     create_table(table_arg),
     create_info(create_info_par),
     select_tables(select_tables_arg),
     alter_info(alter_info_arg),
     m_plock(NULL)
  {}
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);

  int binlog_show_create_table(TABLE **tables, uint count);
  void store_values(List<Item> &values);
  void send_error(uint errcode,const char *err);
  bool send_eof();
  virtual void abort_result_set();

  // Needed for access from local class MY_HOOKS in prepare(), since thd is proteted.
  const THD *get_thd(void) { return thd; }
  const HA_CREATE_INFO *get_create_info() { return create_info; };
  int prepare2(void);
};

#include <myisam.h>

/* 
  Param to create temporary tables when doing SELECT:s 
  NOTE
    This structure is copied using memcpy as a part of JOIN.
*/

class TMP_TABLE_PARAM :public Sql_alloc
{
public:
  List<Item> copy_funcs;
  Copy_field *copy_field, *copy_field_end;
  uchar     *group_buff;
  Item      **items_to_copy;                    /* Fields in tmp table */
  MI_COLUMNDEF *recinfo,*start_recinfo;
  KEY *keyinfo;
  ha_rows end_write_records;
  uint  field_count; 
  uint  func_count;  
  uint  sum_func_count;   
  uint  hidden_field_count;
  uint  group_parts,group_length,group_null_parts;
  uint  quick_group;
  uint  outer_sum_func_count;
  bool  using_outer_summary_function;
  CHARSET_INFO *table_charset; 
  bool schema_table;
  /*
    True if GROUP BY and its aggregate functions are already computed
    by a table access method (e.g. by loose index scan). In this case
    query execution should not perform aggregation and should treat
    aggregate functions as normal functions.
  */
  bool precomputed_group_by;
  bool force_copy_fields;
  bool skip_create_table;
  /*
    If TRUE, create_tmp_field called from create_tmp_table will convert
    all BIT fields to 64-bit longs. This is a workaround the limitation
    that MEMORY tables cannot index BIT columns.
  */
  bool bit_fields_as_long;

  TMP_TABLE_PARAM()
    :copy_field(0), copy_field_end(0), group_parts(0),
     group_length(0), group_null_parts(0), outer_sum_func_count(0),
     using_outer_summary_function(0),
     schema_table(0), precomputed_group_by(0), force_copy_fields(0),
     skip_create_table(FALSE), bit_fields_as_long(0)
  {}
  ~TMP_TABLE_PARAM()
  {
    cleanup();
  }
  void init(void);
  inline void cleanup(void)
  {
    if (copy_field)                             /* Fix for Intel compiler */
    {
      delete [] copy_field;
      copy_field= NULL;
      copy_field_end= NULL;
    }
  }
};

class select_union :public select_result_interceptor
{
  TMP_TABLE_PARAM tmp_table_param;
public:
  TABLE *table;

  select_union() :table(0) {}
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
  bool send_eof();
  bool flush();
  void cleanup();
  bool create_result_table(THD *thd, List<Item> *column_types,
                           bool is_distinct, ulonglong options,
                           const char *alias, bool bit_fields_as_long,
                           bool create_table);
  friend bool mysql_derived_create(THD *thd, LEX *lex, TABLE_LIST *derived);
};

/* Base subselect interface class */
class select_subselect :public select_result_interceptor
{
protected:
  Item_subselect *item;
public:
  select_subselect(Item_subselect *item);
  bool send_data(List<Item> &items)=0;
  bool send_eof() { return 0; };
};

/* Single value subselect interface class */
class select_singlerow_subselect :public select_subselect
{
public:
  select_singlerow_subselect(Item_subselect *item_arg)
    :select_subselect(item_arg)
  {}
  bool send_data(List<Item> &items);
};

/* used in independent ALL/ANY optimisation */
class select_max_min_finder_subselect :public select_subselect
{
  Item_cache *cache;
  bool (select_max_min_finder_subselect::*op)();
  bool fmax;
  bool ignore_nulls;
public:
  select_max_min_finder_subselect(Item_subselect *item_arg, bool mx,
                                  bool ignore_nulls)
    :select_subselect(item_arg), cache(0), fmax(mx), ignore_nulls(ignore_nulls)
  {}
  void cleanup();
  bool send_data(List<Item> &items);
private:
  bool cmp_real();
  bool cmp_int();
  bool cmp_decimal();
  bool cmp_str();
};

/* EXISTS subselect interface class */
class select_exists_subselect :public select_subselect
{
public:
  select_exists_subselect(Item_subselect *item_arg)
    :select_subselect(item_arg){}
  bool send_data(List<Item> &items);
};


/* Structs used when sorting */

typedef struct st_sort_field {
  Field *field;                         /* Field to sort */
  Item  *item;                          /* Item if not sorting fields */
  uint   length;                        /* Length of sort field */
  uint   suffix_length;                 /* Length suffix (0-4) */
  Item_result result_type;              /* Type of item */
  bool reverse;                         /* if descending sort */
  bool need_strxnfrm;                   /* If we have to use strxnfrm() */
} SORT_FIELD;


typedef struct st_sort_buffer {
  uint index;                                   /* 0 or 1 */
  uint sort_orders;
  uint change_pos;                              /* If sort-fields changed */
  char **buff;
  SORT_FIELD *sortorder;
} SORT_BUFFER;

/* Structure for db & table in sql_yacc */

class Table_ident :public Sql_alloc
{
public:
  LEX_STRING db;
  LEX_STRING table;
  SELECT_LEX_UNIT *sel;
  inline Table_ident(THD *thd, LEX_STRING db_arg, LEX_STRING table_arg,
                     bool force)
    :table(table_arg), sel((SELECT_LEX_UNIT *)0)
  {
    if (!force && (thd->client_capabilities & CLIENT_NO_SCHEMA))
      db.str=0;
    else
      db= db_arg;
  }
  inline Table_ident(LEX_STRING table_arg) 
    :table(table_arg), sel((SELECT_LEX_UNIT *)0)
  {
    db.str=0;
  }
  /*
    This constructor is used only for the case when we create a derived
    table. A derived table has no name and doesn't belong to any database.
    Later, if there was an alias specified for the table, it will be set
    by add_table_to_list.
  */
  inline Table_ident(SELECT_LEX_UNIT *s) : sel(s)
  {
    /* We must have a table name here as this is used with add_table_to_list */
    db.str= empty_c_string;                    /* a subject to casedn_str */
    db.length= 0;
    table.str= internal_table_name;
    table.length=1;
  }
  bool is_derived_table() const { return MY_TEST(sel); }
  inline void change_db(char *db_name)
  {
    db.str= db_name; db.length= (uint) strlen(db_name);
  }
};

// this is needed for user_vars hash
class user_var_entry
{
  static const size_t extra_size= sizeof(double);
  char *m_ptr;          // Value
  ulong m_length;       // Value length
  Item_result m_type;   // Value type

  void reset_value()
  { m_ptr= NULL; m_length= 0; }
  void set_value(char *value, ulong length)
  { m_ptr= value; m_length= length; }

  char *internal_buffer_ptr() const
  { return (char *) this + ALIGN_SIZE(sizeof(user_var_entry)); }

  char *name_ptr() const
  { return internal_buffer_ptr() + extra_size; }

  bool realloc(uint length);

  bool alloced()
  { return m_ptr && m_ptr != internal_buffer_ptr(); }

  void free_value()
  {
    if (alloced())
      my_free(m_ptr);
  }

  void copy_name(const Simple_cstring &name)
  {
    name.strcpy(name_ptr());
    entry_name= Name_string(name_ptr(), name.length());
  }

  void init(const Simple_cstring &name)
  {
    copy_name(name);
    reset_value();
    update_query_id= 0;
    collation.set(NULL, DERIVATION_IMPLICIT, 0);
    unsigned_flag= 0;
    /*
      If we are here, we were called from a SET or a query which sets a
      variable. Imagine it is this:
      INSERT INTO t SELECT @a:=10, @a:=@a+1.
      Then when we have a Item_func_get_user_var (because of the @a+1) so we
      think we have to write the value of @a to the binlog. But before that,
      we have a Item_func_set_user_var to create @a (@a:=10), in this we mark
      the variable as "already logged" (line below) so that it won't be logged
      by Item_func_get_user_var (because that's not necessary).
    */
    used_query_id= current_thd->query_id;
    set_type(STRING_RESULT);
  }

  bool store(void *from, uint length, Item_result type);

public:
  user_var_entry() {}                         /* Remove gcc warning */

  Simple_cstring entry_name;  // Variable name
  DTCollation collation;      // Collation with attributes
  query_id_t update_query_id, used_query_id;
  bool unsigned_flag;         // true if unsigned, false if signed

  bool store(void *from, uint length, Item_result type,
             const CHARSET_INFO *cs, Derivation dv, bool unsigned_arg);
  void set_type(Item_result type) { m_type= type; }
  void set_null_value(Item_result type)
  {
    free_value();
    reset_value();
    set_type(type);
  }

  static user_var_entry *create(const Name_string &name)
  {
    user_var_entry *entry;
    size_t size= ALIGN_SIZE(sizeof(user_var_entry)) +
               (name.length() + 1) + extra_size;
    if (!(entry= (user_var_entry*) my_malloc(size, MYF(MY_WME |
                                                       ME_FATALERROR))))
      return NULL;
    entry->init(name);
    return entry;
  }

  void destroy()
  {
    free_value();  // Free the external value buffer
    my_free(this); // Free the instance itself
  }

  /* Routines to access the value and its type */
  const char *ptr() const { return m_ptr; }
  ulong length() const { return m_length; }
  Item_result type() const { return m_type; }
  /* Item-alike routines to access the value */
  double val_real(my_bool *null_value);
  longlong val_int(my_bool *null_value) const;
  String *val_str(my_bool *null_value, String *str, uint decimals);
  my_decimal *val_decimal(my_bool *null_value, my_decimal *result);
};

/*
   Unique -- class for unique (removing of duplicates). 
   Puts all values to the TREE. If the tree becomes too big,
   it's dumped to the file. User can request sorted values, or
   just iterate through them. In the last case tree merging is performed in
   memory simultaneously with iteration, so it should be ~2-3x faster.
 */

class Unique :public Sql_alloc
{
  DYNAMIC_ARRAY file_ptrs;
  ulong max_elements;
  ulonglong max_in_memory_size;
  IO_CACHE file;
  TREE tree;
  uchar *record_pointers;
  bool flush();
  uint size;

public:
  ulong elements;
  Unique(qsort_cmp2 comp_func, void *comp_func_fixed_arg,
         uint size_arg, ulonglong max_in_memory_size_arg);
  ~Unique();
  ulong elements_in_tree() { return tree.elements_in_tree; }
  inline bool unique_add(void *ptr)
  {
    DBUG_ENTER("unique_add");
    DBUG_PRINT("info", ("tree %u - %lu", tree.elements_in_tree, max_elements));
    if (tree.elements_in_tree > max_elements && flush())
      DBUG_RETURN(1);
    DBUG_RETURN(!tree_insert(&tree, ptr, 0, tree.custom_arg));
  }

  bool get(TABLE *table);
  static double get_use_cost(uint *buffer, uint nkeys, uint key_size, 
                             ulonglong max_in_memory_size);

  // Returns the number of bytes needed in imerge_cost_buf.
  inline static int get_cost_calc_buff_size(ulong nkeys, uint key_size, 
                                            ulonglong max_in_memory_size)
  {
    register ulonglong max_elems_in_tree=
      (max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT)+key_size));
    return (int) (sizeof(uint)*(1 + nkeys/max_elems_in_tree));
  }

  void reset();
  bool walk(tree_walk_action action, void *walk_action_arg);

  uint get_size() const { return size; }
  ulonglong get_max_in_memory_size() const { return max_in_memory_size; }

  friend int unique_write_to_file(uchar* key, element_count count, Unique *unique);
  friend int unique_write_to_ptrs(uchar* key, element_count count, Unique *unique);
};


class multi_delete :public select_result_interceptor
{
  TABLE_LIST *delete_tables, *table_being_deleted;
  Unique **tempfiles;
  ha_rows deleted, found;
  uint num_of_tables;
  int error;
  bool do_delete;
  /* True if at least one table we delete from is transactional */
  bool transactional_tables;
  /* True if at least one table we delete from is not transactional */
  bool normal_tables;
  bool delete_while_scanning;
  /*
     error handling (rollback and binlogging) can happen in send_eof()
     so that afterward send_error() needs to find out that.
  */
  bool error_handled;

public:
  multi_delete(TABLE_LIST *dt, uint num_of_tables);
  ~multi_delete();
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
  bool initialize_tables (JOIN *join);
  void send_error(uint errcode,const char *err);
  int do_deletes();
  int do_table_deletes(TABLE *table, bool ignore);
  bool send_eof();
  inline ha_rows num_deleted()
  {
    return deleted;
  }
  virtual void abort_result_set();
};


class multi_update :public select_result_interceptor
{
  TABLE_LIST *all_tables; /* query/update command tables */
  TABLE_LIST *leaves;     /* list of leves of join table tree */
  TABLE_LIST *update_tables, *table_being_updated;
  TABLE **tmp_tables, *main_table, *table_to_update;
  TMP_TABLE_PARAM *tmp_table_param;
  ha_rows updated, found;
  List <Item> *fields, *values;
  List <Item> **fields_for_table, **values_for_table;
  uint table_count;
  /*
   List of tables referenced in the CHECK OPTION condition of
   the updated view excluding the updated table. 
  */
  List <TABLE> unupdated_check_opt_tables;
  Copy_field *copy_field;
  enum enum_duplicates handle_duplicates;
  bool do_update, trans_safe;
  /* True if the update operation has made a change in a transactional table */
  bool transactional_tables;
  bool ignore;
  /* 
     error handling (rollback and binlogging) can happen in send_eof()
     so that afterward send_error() needs to find out that.
  */
  bool error_handled;

  COPY_INFO **update_operations;

public:
  multi_update(TABLE_LIST *ut, TABLE_LIST *leaves_list,
               List<Item> *fields, List<Item> *values,
               enum_duplicates handle_duplicates, bool ignore);
  ~multi_update();
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
  bool initialize_tables (JOIN *join);
  void send_error(uint errcode,const char *err);
  int  do_updates();
  bool send_eof();
  inline ha_rows num_found()
  {
    return found;
  }
  inline ha_rows num_updated()
  {
    return updated;
  }
  virtual void abort_result_set();
};

class my_var : public Sql_alloc  {
public:
  LEX_STRING s;
#ifndef DBUG_OFF
  /*
    Routine to which this Item_splocal belongs. Used for checking if correct
    runtime context is used for variable handling.
  */
  sp_head *sp;
#endif
  bool local;
  uint offset;
  enum_field_types type;
  my_var (LEX_STRING& j, bool i, uint o, enum_field_types t)
    :s(j), local(i), offset(o), type(t)
  {}
  ~my_var() {}
};

class select_dumpvar :public select_result_interceptor {
  ha_rows row_count;
public:
  List<my_var> var_list;
  select_dumpvar()  { var_list.empty(); row_count= 0;}
  ~select_dumpvar() {}
  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
  bool send_data(List<Item> &items);
  bool send_eof();
  virtual bool check_simple_select() const;
  void cleanup();
};

/* Bits in sql_command_flags */

#define CF_CHANGES_DATA           (1U << 0)
/* The 2nd bit is unused -- it used to be CF_HAS_ROW_COUNT. */
#define CF_STATUS_COMMAND         (1U << 2)
#define CF_SHOW_TABLE_COMMAND     (1U << 3)
#define CF_WRITE_LOGS_COMMAND     (1U << 4)

#define CF_REEXECUTION_FRAGILE    (1U << 5)

#define CF_IMPLICIT_COMMIT_BEGIN  (1U << 6)

#define CF_IMPLICIT_COMMIT_END    (1U << 7)

#define CF_AUTO_COMMIT_TRANS  (CF_IMPLICIT_COMMIT_BEGIN | CF_IMPLICIT_COMMIT_END)

#define CF_DIAGNOSTIC_STMT        (1U << 8)

#define CF_CAN_GENERATE_ROW_EVENTS (1U << 9)

#define CF_PREOPEN_TMP_TABLES   (1U << 10)

#define CF_HA_CLOSE             (1U << 11)

#define CF_CAN_BE_EXPLAINED       (1U << 12)

#define CF_OPTIMIZER_TRACE        (1U << 14)

#define CF_DISALLOW_IN_RO_TRANS   (1U << 15)

/* Bits in server_command_flags */

#define CF_SKIP_QUERY_ID        (1U << 0)

#define CF_SKIP_QUESTIONS       (1U << 1)

void add_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var);

void add_diff_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var,
                        STATUS_VAR *dec_var);

/* Inline functions */

inline bool add_item_to_list(THD *thd, Item *item)
{
  return thd->lex->current_select->add_item_to_list(thd, item);
}

inline bool add_value_to_list(THD *thd, Item *value)
{
  return thd->lex->value_list.push_back(value);
}

inline bool add_order_to_list(THD *thd, Item *item, bool asc)
{
  return thd->lex->current_select->add_order_to_list(thd, item, asc);
}

inline bool add_gorder_to_list(THD *thd, Item *item, bool asc)
{
  return thd->lex->current_select->add_gorder_to_list(thd, item, asc);
}

inline bool add_group_to_list(THD *thd, Item *item, bool asc)
{
  return thd->lex->current_select->add_group_to_list(thd, item, asc);
}

#endif /* MYSQL_SERVER */

#endif /* SQL_CLASS_INCLUDED */