SortBufferIndirectIterator Class Reference

Fetch the record IDs from a memory buffer, but the records themselves from the table on disk. More...

#include <basic_row_iterators.h>

Inheritance diagram for SortBufferIndirectIterator:

Public Member Functions
	SortBufferIndirectIterator (THD *thd, Mem_root_array< TABLE * > tables, Sort_result *sort_result, bool ignore_not_found_rows, bool has_null_flags, ha_rows *examined_rows)
	~SortBufferIndirectIterator () override
bool	Init () override
	Initialize or reinitialize the iterator. More...
int	Read () override
	Read a single row. More...
void	SetNullRowFlag (bool) override
	Mark the current row buffer as containing a NULL row or not, so that if you read from it and the flag is true, you'll get only NULLs no matter what is actually in the buffer (typically some old leftover row). More...
void	UnlockRow () override
Public Member Functions inherited from RowIterator
	RowIterator (THD *thd)
virtual	~RowIterator ()=default
	RowIterator (const RowIterator &)=delete
	RowIterator (RowIterator &&)=default
virtual const IteratorProfiler *	GetProfiler () const
	Get profiling data for this iterator (for 'EXPLAIN ANALYZE'). More...
virtual void	SetOverrideProfiler (const IteratorProfiler *profiler)
virtual void	StartPSIBatchMode ()
	Start performance schema batch mode, if supported (otherwise ignored). More...
virtual void	EndPSIBatchModeIfStarted ()
	Ends performance schema batch mode, if started. More...
virtual RowIterator *	real_iterator ()
	If this iterator is wrapping a different iterator (e.g. More...
virtual const RowIterator *	real_iterator () const

Private Attributes
Sort_result *const	m_sort_result
Mem_root_array< TABLE * >	m_tables
uint	m_sum_ref_length
ha_rows *const	m_examined_rows
uchar *	m_cache_pos = nullptr
uchar *	m_cache_end = nullptr
bool	m_ignore_not_found_rows
bool	m_has_null_flags

Additional Inherited Members
Protected Member Functions inherited from RowIterator
THD *	thd () const

Detailed Description

Fetch the record IDs from a memory buffer, but the records themselves from the table on disk.

Used when the above (comment on SortBufferIterator) is not true, UPDATE, DELETE and so forth and SELECT's involving large BLOBs. It is also used for the result of Unique, which returns row IDs in the same format as filesort. In this case the record data is fetched from the handler using the saved reference using the rnd_pos handler call.

Constructor & Destructor Documentation

SortBufferIndirectIterator()

SortBufferIndirectIterator::SortBufferIndirectIterator	(	THD *	thd,
		Mem_root_array< TABLE * >	tables,
		Sort_result *	sort_result,
		bool	ignore_not_found_rows,
		bool	has_null_flags,
		ha_rows *	examined_rows
	)

~SortBufferIndirectIterator()

SortBufferIndirectIterator::~SortBufferIndirectIterator ( )

override

Member Function Documentation

Init()

bool SortBufferIndirectIterator::Init ( )

overridevirtual

Initialize or reinitialize the iterator.

You must always call Init() before trying a Read() (but Init() does not imply Read()).

You can call Init() multiple times; subsequent calls will rewind the iterator (or reposition it, depending on whether the iterator takes in e.g. a Index_lookup) and allow you to read the records anew.

Implements RowIterator.

Read()

int SortBufferIndirectIterator::Read ( )

overridevirtual

Read a single row.

The row data is not actually returned from the function; it is put in the table's (or tables', in case of a join) record buffer, ie., table->records[0].

Return values

0	OK
-1	End of records
1	Error

Implements RowIterator.

SetNullRowFlag()

void SortBufferIndirectIterator::SetNullRowFlag ( bool  is_null_row )

inlineoverridevirtual

Mark the current row buffer as containing a NULL row or not, so that if you read from it and the flag is true, you'll get only NULLs no matter what is actually in the buffer (typically some old leftover row).

This is used for outer joins, when an iterator hasn't produced any rows and we need to produce a NULL-complemented row. Init() or Read() won't necessarily reset this flag, so if you ever set is to true, make sure to also set it to false when needed.

Note that this can be called without Init() having been called first. For example, NestedLoopIterator can hit EOF immediately on the outer iterator, which means the inner iterator doesn't get an Init() call, but will still forward SetNullRowFlag to both inner and outer iterators.

TODO: We shouldn't need this. See the comments on AggregateIterator for a bit more discussion on abstracting out a row interface.

Implements RowIterator.

UnlockRow()

void SortBufferIndirectIterator::UnlockRow ( )

inlineoverridevirtual

Implements RowIterator.

Member Data Documentation

m_cache_end

uchar * SortBufferIndirectIterator::m_cache_end = nullptr

private

m_cache_pos

uchar* SortBufferIndirectIterator::m_cache_pos = nullptr

private

m_examined_rows

ha_rows* const SortBufferIndirectIterator::m_examined_rows

private

m_has_null_flags

bool SortBufferIndirectIterator::m_has_null_flags

private

m_ignore_not_found_rows

bool SortBufferIndirectIterator::m_ignore_not_found_rows

private

m_sort_result

Sort_result* const SortBufferIndirectIterator::m_sort_result

private

m_sum_ref_length

uint SortBufferIndirectIterator::m_sum_ref_length

private

m_tables

Mem_root_array<TABLE *> SortBufferIndirectIterator::m_tables

private

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

• sql/iterators/basic_row_iterators.h
• sql/iterators/sorting_iterator.cc