Explain_format_JSON Class Reference

Formatter class for EXPLAIN FORMAT=JSON output. More...

#include <opt_explain_json.h>

Inheritance diagram for Explain_format_JSON:

Public Member Functions
	Explain_format_JSON (std::optional< std::string_view > explain_into_variable_name)
bool	is_hierarchical () const override
	A hierarchical text or a plain table. More...
bool	is_iterator_based (THD *explain_thd, const THD *query_thd) const override
	Format versions newer than Linear are always going to be iterator-based. More...
bool	send_headers (Query_result *result) override
	Send EXPLAIN header item(s) to output stream. More...
bool	begin_context (enum_parsing_context context, Query_expression *subquery, const Explain_format_flags *flags) override
	Enter a specified context. More...
bool	end_context (enum_parsing_context context) override
	Leave the current context. More...
bool	flush_entry () override
	Flush TABLE/JOIN_TAB property set. More...
qep_row *	entry () override
	Get a pointer to the current TABLE/JOIN_TAB property set. More...
std::string	ExplainJsonToString (Json_object *json) override
	Convert Json object to string. More...
Public Member Functions inherited from Explain_format
virtual	~Explain_format ()=default
bool	is_explain_into () const
	Whether the output of an EXPLAIN statement should be stored in a user variable or sent to the client. More...
bool	is_explain_for_schema () const
	Whether the EXPLAIN statement should be run in another schema than the current active schema. More...
std::string_view	explain_into_variable_name () const
	Returns the name of the user variable the output of this EXPLAIN statement is to be stored in. More...

Private Attributes
opt_explain_json_namespace::context *	current_context
	current tree node More...

Additional Inherited Members
Public Attributes inherited from Explain_format
LEX_CSTRING	m_schema_name_for_explain
Protected Member Functions inherited from Explain_format
	Explain_format ()
	Explain_format (std::optional< std::string_view > explain_into_variable_name)
Protected Attributes inherited from Explain_format
Query_result *	output
	output resulting data there More...

Detailed Description

Formatter class for EXPLAIN FORMAT=JSON output.

Constructor & Destructor Documentation

Explain_format_JSON()

Explain_format_JSON::Explain_format_JSON ( std::optional< std::string_view >  explain_into_variable_name )

inlineexplicit

Member Function Documentation

begin_context()

bool Explain_format_JSON::begin_context ( enum_parsing_context  context, Query_expression *  subquery, const Explain_format_flags *  flags  )

overridevirtual

Enter a specified context.

Parameters

context	context type
subquery	for CTX_WHERE: unit of the subquery
flags	Format flags, see Explain_format_flags.

Implements Explain_format.

end_context()

bool Explain_format_JSON::end_context ( enum_parsing_context  context )

overridevirtual

Leave the current context.

Parameters

context

current context type (for validation/debugging)

Implements Explain_format.

entry()

qep_row * Explain_format_JSON::entry ( )

overridevirtual

Get a pointer to the current TABLE/JOIN_TAB property set.

Implements Explain_format.

ExplainJsonToString()

std::string Explain_format_JSON::ExplainJsonToString ( Json_object *  json )

overridevirtual

Convert Json object to string.

Should only be called for iterator-based formats.

Reimplemented from Explain_format.

flush_entry()

bool Explain_format_JSON::flush_entry ( )

inlineoverridevirtual

Flush TABLE/JOIN_TAB property set.

For traditional EXPLAIN: output a single EXPLAIN row.

Implements Explain_format.

is_hierarchical()

bool Explain_format_JSON::is_hierarchical ( ) const

inlineoverridevirtual

A hierarchical text or a plain table.

Return values

true	Formatter produces hierarchical text
false	Traditional explain

Implements Explain_format.

is_iterator_based()

bool Explain_format_JSON::is_iterator_based ( THD *  explain_thd, const THD *  query_thd  ) const

overridevirtual

Format versions newer than Linear are always going to be iterator-based.

Reimplemented from Explain_format.

send_headers()

bool Explain_format_JSON::send_headers ( Query_result *  result )

overridevirtual

Send EXPLAIN header item(s) to output stream.

Note

: This function caches the output result set pointer for further use.

Parameters

result

output result set

Return values

false	OK
true	Error

Reimplemented from Explain_format.

Member Data Documentation

current_context

opt_explain_json_namespace::context* Explain_format_JSON::current_context

private

current tree node

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

• sql/opt_explain_json.h
• sql/opt_explain_json.cc