qep_row Class Reference

#include <opt_explain_format.h>

Inheritance diagram for qep_row:

List of all members.

Classes
struct	column
struct	extra
struct	mem_root_str
Public Member Functions
void	cleanup ()
virtual void	register_where_subquery (SELECT_LEX_UNIT *subquery)
Public Attributes
column< uint >	col_id
	"id" column: seq. number of SELECT withing the query
column< SELECT_LEX::type_enum >	col_select_type
	"select_type" column
mem_root_str	col_table_name
	"table" to which the row of output refers
List< const char >	col_partitions
	"partitions" column
mem_root_str	col_join_type
	"type" column, see join_type_str array
List< const char >	col_possible_keys
	"possible_keys": comma-separated list
mem_root_str	col_key
	"key" column: index that is actually decided to use
mem_root_str	col_key_len
	"key_length" column: length of the "key" above
List< const char >	col_ref
	"ref":columns/constants which are compared to "key"
column< longlong >	col_rows
	"rows": estimated number of examined table rows
column< float >	col_filtered
	"filtered": % of rows filtered by condition
List< extra >	col_extra
	"extra" column (traditional) or property list
mem_root_str	col_message
	replaces "Extra" column if not empty
mem_root_str	col_attached_condition
	former "Using where"
uint	query_block_id
	query block id for materialized subqueries
List < opt_explain_json_namespace::context >	derived_from
List< const char >	col_key_parts
	used parts of the key
bool	is_dependent
bool	is_cacheable
bool	using_temporary
bool	is_materialized_from_subquery
bool	is_update
bool	is_delete

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Detailed Description

Helper class for table property buffering

For traditional EXPLAIN this structure contains cached data for a single output row.

For hierarchical EXPLAIN this structure contains property values for a single CTX_TABLE/CTX_JOIN_TAB context node of the intermediate tree.

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Member Function Documentation

virtual void qep_row::register_where_subquery

(

SELECT_LEX_UNIT *

subquery

)

[inline, virtual]

Remember a subquery's unit

JOIN_TAB inside a JOIN, a table in a join-less query (single-table UPDATE/DELETE) or a table that's optimized out may have a WHERE condition. We create the Explain_context of such a JOIN_TAB or table when the Explain_context objects of its in-WHERE subqueries don't exist. This function collects unit pointers of WHERE subqueries that are associated with the current JOIN_TAB or table. Then we can match these units with units of newly-created Explain_context objects of WHERE subqueries.

Parameters:

subquery

WHERE clause subquery's unit

Reimplemented in opt_explain_json_namespace::join_tab_ctx.

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Member Data Documentation

List<opt_explain_json_namespace::context> qep_row::derived_from

List of "derived" subquery trees

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The documentation for this class was generated from the following file:

• opt_explain_format.h