Explain_format_tree Class Reference

#include <opt_explain_traditional.h>

Inheritance diagram for Explain_format_tree:

Public Member Functions
	Explain_format_tree ()=default
bool	is_hierarchical () const override
	A hierarchical text or a plain table. More...
bool	send_headers (Query_result *) override
	Send EXPLAIN header item(s) to output stream. More...
bool	begin_context (enum_parsing_context, Query_expression *, const Explain_format_flags *) override
	Enter a specified context. More...
bool	end_context (enum_parsing_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...
bool	is_iterator_based (THD *explain_thd, const THD *query_thd) const override
	Whether the format closely resembles the final plan to be executed by execution iterators (See RowIterator). More...
std::string	ExplainJsonToString (Json_object *json) override
	Convert Json object to string. More...
void	ExplainPrintTreeNode (const Json_dom *json, int level, std::string *explain, std::vector< std::string > *tokens_for_force_subplan)
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 Member Functions
bool	push_select_type (mem_root_deque< Item * > *items)
void	AppendChildren (const Json_dom *children, int level, std::string *explain, std::vector< std::string > *tokens_for_force_subplan, std::string *child_token_digest)
void	ExplainPrintCosts (const Json_object *obj, std::string *explain)

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...

Constructor & Destructor Documentation

Explain_format_tree()

Explain_format_tree::Explain_format_tree ( )

default

Member Function Documentation

AppendChildren()

void Explain_format_tree::AppendChildren ( const Json_dom *  children, int  level, std::string *  explain, std::vector< std::string > *  tokens_for_force_subplan, std::string *  child_token_digest  )

private

begin_context()

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

inlineoverridevirtual

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_tree::end_context ( enum_parsing_context  context )

inlineoverridevirtual

Leave the current context.

Parameters

context

current context type (for validation/debugging)

Implements Explain_format.

entry()

qep_row * Explain_format_tree::entry ( )

inlineoverridevirtual

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

Implements Explain_format.

ExplainJsonToString()

string Explain_format_tree::ExplainJsonToString ( Json_object *  json )

overridevirtual

Convert Json object to string.

Reimplemented from Explain_format.

ExplainPrintCosts()

void Explain_format_tree::ExplainPrintCosts ( const Json_object *  obj, std::string *  explain  )

private

ExplainPrintTreeNode()

void Explain_format_tree::ExplainPrintTreeNode	(	const Json_dom *	json,
		int	level,
		std::string *	explain,
		std::vector< std::string > *	tokens_for_force_subplan
	)

flush_entry()

bool Explain_format_tree::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_tree::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_tree::is_iterator_based ( THD *  explain_thd, const THD *  query_thd  ) const

inlineoverridevirtual

Whether the format closely resembles the final plan to be executed by execution iterators (See RowIterator).

These formats share a common logic that uses AccessPath structure to generate the information, so they all display exactly the same information, even though the style of each format might be different.

Note

: The new json format for hypergraph and the tree format are examples of iterator-based formats.

Return values

true	Format is Iterator-based.
false	Format is not Iterator-based.

Reimplemented from Explain_format.

push_select_type()

bool Explain_format_tree::push_select_type ( mem_root_deque< Item * > *  items )

private

send_headers()

bool Explain_format_tree::send_headers ( Query_result *  result )

inlineoverridevirtual

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.

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

• sql/opt_explain_traditional.h
• sql/join_optimizer/explain_access_path.cc