sql_const.h File Reference

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Defines
#define	LIBLEN   FN_REFLEN-FN_LEN /* Max l{ngd p} dev */
#define	MAX_DBKEY_LENGTH   (NAME_LEN*2+1+1+4+4)
#define	MAX_ALIAS_NAME   256
#define	MAX_FIELD_NAME   34 /* Max colum name length +2 */
#define	MAX_SYS_VAR_LENGTH   32
#define	MAX_KEY   MAX_INDEXES /* Max used keys */
#define	MAX_REF_PARTS   16U /* Max parts used as ref */
#define	MAX_KEY_LENGTH   3072U /* max possible key */
#define	MAX_REFLENGTH   4 /* Max length for record ref */
#define	MAX_HOSTNAME   61 /* len+1 in mysql.user */
#define	MAX_MBWIDTH   3 /* Max multibyte sequence */
#define	MAX_FIELD_CHARLENGTH   255
#define	MAX_FIELD_VARCHARLENGTH   65535
#define	MAX_FIELD_BLOBLENGTH   UINT_MAX32 /* cf field_blob::get_length() */
#define	CONVERT_IF_BIGGER_TO_BLOB   512 /* Used for CREATE ... SELECT */
#define	MAX_FIELD_WIDTH   (MAX_FIELD_CHARLENGTH*MAX_MBWIDTH+1)
#define	MAX_BIT_FIELD_LENGTH   64 /* Max length in bits for bit fields */
#define	MAX_DATE_WIDTH   10 /* YYYY-MM-DD */
#define	MAX_TIME_WIDTH   10 /* -838:59:59 */
#define	MAX_TIME_FULL_WIDTH   23 /* -DDDDDD HH:MM:SS.###### */
#define	MAX_DATETIME_FULL_WIDTH   29 /* YYYY-MM-DD HH:MM:SS.###### AM */
#define	MAX_DATETIME_WIDTH   19 /* YYYY-MM-DD HH:MM:SS */
#define	MAX_DATETIME_COMPRESSED_WIDTH   14 /* YYYYMMDDHHMMSS */
#define	DATE_INT_DIGITS   8 /* YYYYMMDD */
#define	TIME_INT_DIGITS   7 /* hhhmmss */
#define	DATETIME_INT_DIGITS   14 /* YYYYMMDDhhmmss */
#define	MAX_TABLES   (sizeof(table_map)*8-3) /* Max tables in join */
#define	PARAM_TABLE_BIT   (((table_map) 1) << (sizeof(table_map)*8-3))
#define	OUTER_REF_TABLE_BIT   (((table_map) 1) << (sizeof(table_map)*8-2))
#define	RAND_TABLE_BIT   (((table_map) 1) << (sizeof(table_map)*8-1))
#define	PSEUDO_TABLE_BITS
#define	MAX_FIELDS   4096 /* Limit in the .frm file */
#define	MAX_PARTITIONS   8192
#define	MAX_SELECT_NESTING   (sizeof(nesting_map)*8-1)
#define	DEFAULT_SORT_MEMORY   (256UL* 1024UL)
#define	MIN_SORT_MEMORY   (32UL * 1024UL)
#define	STRING_BUFFER_USUAL_SIZE   80
#define	MEM_ROOT_BLOCK_SIZE   8192
#define	MEM_ROOT_PREALLOC   8192
#define	TRANS_MEM_ROOT_BLOCK_SIZE   4096
#define	TRANS_MEM_ROOT_PREALLOC   4096
#define	DEFAULT_ERROR_COUNT   64
#define	EXTRA_RECORDS   10 /* Extra records in sort */
#define	SCROLL_EXTRA   5 /* Extra scroll-rows. */
#define	FIELD_NAME_USED   ((uint) 32768) /* Bit set if fieldname used */
#define	FORM_NAME_USED   ((uint) 16384) /* Bit set if formname used */
#define	FIELD_NR_MASK   16383 /* To get fieldnumber */
#define	FERR   -1 /* Error from my_functions */
#define	CREATE_MODE   0 /* Default mode on new files */
#define	NAMES_SEP_CHAR   '\377' /* Char to sep. names */
#define	READ_RECORD_BUFFER   (uint) (IO_SIZE*8) /* Pointer_buffer_size */
#define	DISK_BUFFER_SIZE   (uint) (IO_SIZE*16) /* Size of diskbuffer */
#define	FRM_VER_TRUE_VARCHAR   (FRM_VER+4) /* 10 */
#define	ACL_CACHE_SIZE   256
#define	MAX_PASSWORD_LENGTH   32
#define	HOST_CACHE_SIZE   128
#define	MAX_ACCEPT_RETRY   10
#define	MAX_FIELDS_BEFORE_HASH   32
#define	USER_VARS_HASH_SIZE   16
#define	TABLE_OPEN_CACHE_MIN   400
#define	TABLE_OPEN_CACHE_DEFAULT   2000
#define	TABLE_DEF_CACHE_DEFAULT   400
#define	MAX_CONNECTIONS_DEFAULT   151
#define	TABLE_DEF_CACHE_MIN   400
#define	STACK_MIN_SIZE   16000
#define	STACK_MIN_SIZE_FOR_OPEN   1024*80
#define	STACK_BUFF_ALLOC   352
	For stack overrun checks.
#define	QUERY_ALLOC_BLOCK_SIZE   8192
#define	QUERY_ALLOC_PREALLOC_SIZE   8192
#define	TRANS_ALLOC_BLOCK_SIZE   4096
#define	TRANS_ALLOC_PREALLOC_SIZE   4096
#define	RANGE_ALLOC_BLOCK_SIZE   4096
#define	ACL_ALLOC_BLOCK_SIZE   1024
#define	UDF_ALLOC_BLOCK_SIZE   1024
#define	TABLE_ALLOC_BLOCK_SIZE   1024
#define	WARN_ALLOC_BLOCK_SIZE   2048
#define	WARN_ALLOC_PREALLOC_SIZE   1024
#define	MIN_FILE_LENGTH_TO_USE_ROW_CACHE   (10L*1024*1024)
#define	MIN_ROWS_TO_USE_TABLE_CACHE   100
#define	MIN_ROWS_TO_USE_BULK_INSERT   100
#define	ROW_EVALUATE_COST   0.20
#define	ROWID_COMPARE_COST   0.10
#define	DISK_SEEK_BASE_COST   ((double)0.9)
#define	BLOCKS_IN_AVG_SEEK   128
#define	DISK_SEEK_PROP_COST   ((double)0.1/BLOCKS_IN_AVG_SEEK)
#define	MATCHING_ROWS_IN_OTHER_TABLE   10
#define	HEAP_TEMPTABLE_CREATE_COST   2.0
#define	HEAP_TEMPTABLE_ROW_COST   0.2
#define	DISK_TEMPTABLE_CREATE_COST   40.0
#define	DISK_TEMPTABLE_ROW_COST   1.0
#define	MY_CHARSET_BIN_MB_MAXLEN   1
#define	KEY_DEFAULT_PACK_LENGTH   8
#define	PROCESS_LIST_WIDTH   100
#define	PROCESS_LIST_INFO_WIDTH   65535
#define	PRECISION_FOR_DOUBLE   53
#define	PRECISION_FOR_FLOAT   24
#define	MAX_FLOAT_STR_LENGTH   (FLT_DIG + 6)
#define	MAX_DOUBLE_STR_LENGTH   (DBL_DIG + 7)
#define	CONNECT_TIMEOUT   10
#define	DEFAULT_CONCURRENCY   10
#define	DELAYED_LIMIT   100
#define	DELAYED_QUEUE_SIZE   1000
#define	DELAYED_WAIT_TIMEOUT   5*60
#define	LONG_TIMEOUT   ((ulong) 3600L*24L*365L)
#define	MAX_TIME_ZONE_NAME_LENGTH   (NAME_LEN + 1)
#define	INTERRUPT_PRIOR   10
#define	CONNECT_PRIOR   9
#define	WAIT_PRIOR   8
#define	QUERY_PRIOR   6

---

Detailed Description

File containing constants that can be used throughout the server.

Note:

This file shall not contain any includes of any kinds.

---

Define Documentation

#define CONVERT_IF_BIGGER_TO_BLOB   512 /* Used for CREATE ... SELECT */

CHAR and VARCHAR fields longer than this number of characters are converted to BLOB. Non-character fields longer than this number of bytes are converted to BLOB. Comparisons should be '>' or '<='.

#define DELAYED_LIMIT   100

pause after xxx inserts

#define DELAYED_WAIT_TIMEOUT   5*60

Wait for delayed insert

#define KEY_DEFAULT_PACK_LENGTH   8

Don't pack string keys shorter than this (if PACK_KEYS=1 isn't used).

#define MATCHING_ROWS_IN_OTHER_TABLE   10

Number of rows in a reference table when refereed through a not unique key. This value is only used when we don't know anything about the key distribution.

#define MAX_CONNECTIONS_DEFAULT   151

Maximum number of connections default value. 151 is larger than Apache's default max children, to avoid "too many connections" error in a common setup.

#define MAX_TIME_ZONE_NAME_LENGTH   (NAME_LEN + 1)

Maximum length of time zone name that we support (Time zone name is char(64) in db). mysqlbinlog needs it.

#define PROCESS_LIST_WIDTH   100

Characters shown for the command in 'show processlist'.

#define PSEUDO_TABLE_BITS

Value:

(PARAM_TABLE_BIT | OUTER_REF_TABLE_BIT | \
                           RAND_TABLE_BIT)

#define ROW_EVALUATE_COST   0.20

The following is used to decide if MySQL should use table scanning instead of reading with keys. The number says how costly evaluation of the filter condition for a row is compared to reading one extra row from a table.

#define ROWID_COMPARE_COST   0.10

Cost of comparing a rowid compared to reading one row from a table.

#define TABLE_DEF_CACHE_MIN   400

We must have room for at least 400 table definitions in the table cache, since otherwise there is no chance prepared statements that use these many tables can work. Prepared statements use table definition cache ids (table_map_id) as table version identifiers. If the table definition cache size is less than the number of tables used in a statement, the contents of the table definition cache is guaranteed to rotate between a prepare and execute. This leads to stable validation errors. In future we shall use more stable version identifiers, for now the only solution is to ensure that the table definition cache can contain at least all tables of a given statement.