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opt_explain_json_namespace::message_ctx Class Reference
Inheritance diagram for opt_explain_json_namespace::message_ctx:
opt_explain_json_namespace::joinable_ctx opt_explain_json_namespace::table_with_where_and_derived opt_explain_json_namespace::context opt_explain_json_namespace::table_base_ctx Explain_context opt_explain_json_namespace::context qep_row Sql_alloc Explain_context Sql_alloc Sql_alloc

List of all members.

Public Member Functions

 message_ctx (context *parent_arg)
virtual bool format_body (Opt_trace_context *json, Opt_trace_object *obj)
virtual size_t id (bool hide)
virtual bool cacheable ()
virtual bool dependent ()
virtual qep_rowentry ()
virtual bool format_derived (Opt_trace_context *json)
 Helper function to format output for derived subquery if any.
virtual bool format_where (Opt_trace_context *json)
 Helper function to format output for associated WHERE subqueries if any.
virtual bool find_and_set_derived (context *subquery)
virtual bool add_where_subquery (subquery_ctx *ctx, SELECT_LEX_UNIT *subquery)

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.

Member Function Documentation

virtual bool opt_explain_json_namespace::message_ctx::add_where_subquery ( subquery_ctx ctx,
SELECT_LEX_UNIT *  subquery 
) [inline, virtual]

Associate WHERE subqueries of given context and unit with this object

ctxContext of WHERE subquery
subqueryFor CTX_JOIN_TAB: match given unit with a previously collected by the register_where_subquery function.

Reimplemented from opt_explain_json_namespace::context.

virtual bool opt_explain_json_namespace::message_ctx::find_and_set_derived ( context subquery) [inline, virtual]

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

subqueryDerived subquery node
Return values:
falseCan't associate: this node or its child nodes are not derived from the subquery

Reimplemented from opt_explain_json_namespace::context.

virtual bool opt_explain_json_namespace::message_ctx::format_body ( Opt_trace_context json,
Opt_trace_object obj 
) [inline, virtual]

Format JSON object body

objObject of this body
Return values:

Implements opt_explain_json_namespace::context.

virtual size_t opt_explain_json_namespace::message_ctx::id ( bool  hide) [inline, virtual]

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

hideif true, ban the output of K_SELECT_ID JSON property in the underlying table_with_where_and_derived_ctx objects
"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:
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