Node class for CTX_MESSAGE. More...

Inheritance diagram for opt_explain_json_namespace::message_ctx:

Public Member Functions
	message_ctx (context *parent_arg)

bool	format_body (Opt_trace_context json, Opt_trace_object obj) override
	Format JSON object body. More...

size_t	id (bool hide) override
	Analogue of the "id" column in the traditional EXPLAIN output. More...

bool	cacheable () override

bool	dependent () override

qep_row *	entry () override

bool	format_derived (Opt_trace_context *json) override
	Helper function to format output for derived subquery if any. More...

bool	format_where (Opt_trace_context *json) override
	Helper function to format output for associated WHERE subqueries if any. More...

bool	find_and_set_derived (context *subquery) override
	Try to associate a derived subquery node with this or underlying node. More...

int	add_where_subquery (subquery_ctx ctx, Query_expression ) override
	Associate WHERE subqueries of given context and unit with this object. More...

Public Member Functions inherited from opt_explain_json_namespace::joinable_ctx
	joinable_ctx (enum_parsing_context type_arg, const char name_arg, context parent_arg)

Public Member Functions inherited from opt_explain_json_namespace::context
	context (enum_parsing_context type_arg, const char name_arg, context parent_arg)

virtual	~context ()=default

virtual bool	format (Opt_trace_context *json)
	Pass the node with its child nodes to a JSON formatter. More...

bool	is_query_block () const

virtual enum_mod_type	get_mod_type ()

virtual void	set_child (context *)
	Associate a child node with this node. More...

virtual void	set_setop_result (setop_result_ctx *)
	associate CTX_UNION_RESULT node with CTX_UNION node More...

virtual bool	add_subquery (subquery_list_enum subquery_type, subquery_ctx *ctx)
	Append a subquery node to the specified list of the unit node. More...

virtual bool	format_nested_loop (Opt_trace_context *json)
	Format nested loop join subtree (if any) to JSON formatter. More...

virtual bool	add_join_tab (joinable_ctx *ctx)
	Add a CTX_QEP_TAB node to a CTX_JOIN node. More...

virtual void	set_sort (sort_ctx *ctx)
	Set nested ORDER BY/GROUP BY/DISTINCT node to `ctx`. More...

virtual void	set_window (window_ctx *ctx)
	Set nested WINDOW node to `ctx`. More...

virtual bool	add_query_spec (context *ctx)
	Add a query specification node to the CTX_UNION node. More...

virtual bool	format_query_expression (Opt_trace_context *)
	Helper function to format output for HAVING, ORDER/GROUP BY subqueries. More...

Public Member Functions inherited from Explain_context
	Explain_context (enum_parsing_context type_arg)

Public Member Functions inherited from opt_explain_json_namespace::table_with_where_and_derived
	table_with_where_and_derived (enum_parsing_context type_arg, const char name_arg, context parent_arg)

Public Member Functions inherited from opt_explain_json_namespace::table_base_ctx
	table_base_ctx (enum_parsing_context type_arg, const char name_arg, context parent_arg)

Public Member Functions inherited from qep_row
	qep_row ()

virtual	~qep_row ()=default

void	cleanup ()

virtual void	register_where_subquery (Query_expression *subquery)
	Remember a subquery's unit. More...

void	format_extra (Opt_trace_object *obj)

Additional Inherited Members
Public Attributes inherited from opt_explain_json_namespace::context
context *	parent
	link to parent node or NULL More...

Public Attributes inherited from Explain_context
enum_parsing_context	type
	type tag More...

Public Attributes inherited from opt_explain_json_namespace::table_with_where_and_derived
List< subquery_ctx >	where_subqueries
	associated WHERE clause subqueries More...

Public Attributes inherited from qep_row
column< uint >	col_id
	"id" column: seq. number of SELECT within the query More...

column< enum_explain_type >	col_select_type
	"select_type" column More...

mem_root_str	col_table_name
	"table" to which the row of output refers More...

List< const char >	col_partitions
	"partitions" column More...

mem_root_str	col_join_type
	"type" column, see join_type_str array More...

List< const char >	col_possible_keys
	"possible_keys": comma-separated list More...

mem_root_str	col_key
	"key" column: index that is actually decided to use More...

mem_root_str	col_key_len
	"key_length" column: length of the "key" above More...

List< const char >	col_ref
	"ref":columns/constants which are compared to "key" More...

column< float >	col_filtered
	"filtered": % of rows filtered by condition More...

List< extra >	col_extra
	"extra" column (traditional) or property list More...

mem_root_str	col_message
	replaces "Extra" column if not empty More...

mem_root_str	col_attached_condition
	former "Using where" More...

column< ulonglong >	col_rows
	"rows": estimated number of examined table rows per single scan More...

column< ulonglong >	col_prefix_rows
	"rows": estimated number of examined table rows per query More...

column< double >	col_read_cost
	Time to read the table. More...

column< double >	col_prefix_cost
	Cost of the partial join including this table. More...

column< double >	col_cond_cost
	Cost of evaluating conditions on this table per query. More...

mem_root_str	col_data_size_query
	Size of data expected to be read per query. More...

List< const char >	col_used_columns
	List of used columns. More...

List< const char >	col_partial_update_columns
	List of columns that can be updated using partial update. More...

uint	query_block_id
	query block id for materialized subqueries More...

List< opt_explain_json_namespace::context >	derived_from
	List of "derived" subquery trees. More...

List< const char >	col_key_parts
	used parts of the key More...

bool	is_dependent

bool	is_cacheable

bool	using_temporary

enum_mod_type	mod_type

bool	is_materialized_from_subquery

uint	derived_clone_id
	If a clone of a materialized derived table, this is the ID of the first underlying query block of the first materialized derived table. More...

List< Window > *	m_windows
	Windows to describe in this node. More...

Protected Attributes inherited from opt_explain_json_namespace::context
const char *	name

Protected Attributes inherited from opt_explain_json_namespace::table_base_ctx
bool	is_hidden_id
	if true, don't output K_SELECT_ID property More...

Detailed Description

Node class for CTX_MESSAGE.

This class is designed to represent fake tables with some messages in the "extra" column ("Impossible where" etc). We do EXPLAIN of these fake tables to replace explanation of: 1) usual actual JOIN_TABs of the whole JOIN or 2) a modifying TABLE of single-table UPDATE/DELETE/etc. So, message_ctx always represent a single half-empty fake table in a "query_block" node with optional subqueries.

Constructor & Destructor Documentation

◆ message_ctx()

opt_explain_json_namespace::message_ctx::message_ctx ( context * parent_arg )

inlineexplicit

Member Function Documentation

◆ add_where_subquery()

int opt_explain_json_namespace::message_ctx::add_where_subquery	(	subquery_ctx *	ctx,
		Query_expression *	subquery
	)

inlineoverridevirtual

Associate WHERE subqueries of given context and unit with this object.

Parameters

ctx	Context of WHERE subquery
subquery	For CTX_QEP_TAB: match given unit with a previously collected by the register_where_subquery function.

Returns: -1 subquery wasn't found 0 subqusery were added 1 error occurred

Reimplemented from opt_explain_json_namespace::context.

◆ cacheable()

bool opt_explain_json_namespace::message_ctx::cacheable ( )

inlineoverridevirtual

Reimplemented from opt_explain_json_namespace::context.

◆ dependent()

bool opt_explain_json_namespace::message_ctx::dependent ( )

inlineoverridevirtual

Reimplemented from opt_explain_json_namespace::context.

◆ entry()

qep_row * opt_explain_json_namespace::message_ctx::entry ( )

inlineoverridevirtual

Reimplemented from opt_explain_json_namespace::context.

◆ find_and_set_derived()

bool opt_explain_json_namespace::message_ctx::find_and_set_derived ( context * subquery )

inlineoverridevirtual

Try to associate a derived subquery node with this or underlying node.

Parameters

subquery Derived subquery node

Return values

true	Success
false	Can't associate: this node or its child nodes are not derived from the subquery

Reimplemented from opt_explain_json_namespace::context.

◆ format_body()

bool opt_explain_json_namespace::message_ctx::format_body	(	Opt_trace_context *	json,
		Opt_trace_object *	obj
	)

inlineoverridevirtual

Format JSON object body.

Parameters

json	Formatter
obj	Object of this body

Return values

false	Ok
true	Error

Implements opt_explain_json_namespace::context.

◆ format_derived()

bool opt_explain_json_namespace::message_ctx::format_derived ( Opt_trace_context * )

inlineoverridevirtual

Helper function to format output for derived subquery if any.

Reimplemented from opt_explain_json_namespace::table_with_where_and_derived.

◆ format_where()

bool opt_explain_json_namespace::message_ctx::format_where ( Opt_trace_context * )

inlineoverridevirtual

Helper function to format output for associated WHERE subqueries if any.

Reimplemented from opt_explain_json_namespace::table_with_where_and_derived.

◆ id()

size_t opt_explain_json_namespace::message_ctx::id ( bool hide )

inlineoverridevirtual

Analogue of the "id" column in the traditional EXPLAIN output.

Parameters

hide	if true, ban the output of K_SELECT_ID JSON property in the underlying table_with_where_and_derived_ctx objects

Returns: "Select number" that is associated with this node

Reimplemented from opt_explain_json_namespace::table_with_where_and_derived.

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

sql/opt_explain_json.cc

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ message_ctx()

Member Function Documentation

◆ add_where_subquery()

◆ cacheable()

◆ dependent()

◆ entry()

◆ find_and_set_derived()

◆ format_body()

◆ format_derived()

◆ format_where()

◆ id()