ReverseIndexRangeScanIterator Class Reference

An iterator much like IndexRangeScanIterator, but it scans in the reverse order. More...

#include <reverse_index_range_scan.h>

Inheritance diagram for ReverseIndexRangeScanIterator:

Public Member Functions
	ReverseIndexRangeScanIterator (THD *thd, TABLE *table, ha_rows *examined_rows, double expected_rows, int index, MEM_ROOT *return_mem_root, uint mrr_flags, Bounds_checked_array< QUICK_RANGE * > ranges, bool using_extended_key_parts)
	~ReverseIndexRangeScanIterator () override
int	Read () override
	Read a single row. More...
bool	Init () override
	Initialize or reinitialize the iterator. More...
Public Member Functions inherited from TableRowIterator
	TableRowIterator (THD *thd, TABLE *table)
void	UnlockRow () override
	The default implementation of unlock-row method of RowIterator, used in all access methods except EQRefIterator. More...
void	SetNullRowFlag (bool is_null_row) 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	StartPSIBatchMode () override
	Start performance schema batch mode, if supported (otherwise ignored). More...
void	EndPSIBatchModeIfStarted () override
	Ends performance schema batch mode, if started. More...
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 ([[maybe_unused]] const IteratorProfiler *profiler)
virtual RowIterator *	real_iterator ()
	If this iterator is wrapping a different iterator (e.g. More...
virtual const RowIterator *	real_iterator () const

Private Member Functions
bool	range_reads_after_key (QUICK_RANGE *range)
int	cmp_prev (QUICK_RANGE *range)

Static Private Member Functions
static range_seq_t	quick_range_rev_seq_init (void *init_param, uint, uint)

Private Attributes
const uint	m_index
ha_rows	m_expected_rows
ha_rows *	m_examined_rows
MEM_ROOT *	mem_root
bool	inited = false
MY_BITMAP	column_bitmap
uint	m_mrr_flags
Bounds_checked_array< QUICK_RANGE * >	ranges
QUICK_RANGE_SEQ_CTX	qr_traversal_ctx
QUICK_RANGE *	last_range
int	current_range_idx
KEY_PART_INFO *	key_part_info
bool	m_using_extended_key_parts {false}

Additional Inherited Members
Protected Member Functions inherited from TableRowIterator
int	HandleError (int error)
void	PrintError (int error)
TABLE *	table () const
Protected Member Functions inherited from RowIterator
THD *	thd () const

Detailed Description

An iterator much like IndexRangeScanIterator, but it scans in the reverse order.

This makes it at times more complicated, but since it doesn't support being a part of a ROR scan, it is also less complicated in many ways.

One could argue that this and IndexRangeScanIterator should be factored into a common base class with separate _ASC and _DESC classes, but they don't actually duplicate that much code.

Constructor & Destructor Documentation

ReverseIndexRangeScanIterator()

ReverseIndexRangeScanIterator::ReverseIndexRangeScanIterator	(	THD *	thd,
		TABLE *	table,
		ha_rows *	examined_rows,
		double	expected_rows,
		int	index,
		MEM_ROOT *	return_mem_root,
		uint	mrr_flags,
		Bounds_checked_array< QUICK_RANGE * >	ranges,
		bool	using_extended_key_parts
	)

~ReverseIndexRangeScanIterator()

ReverseIndexRangeScanIterator::~ReverseIndexRangeScanIterator ( )

override

Member Function Documentation

cmp_prev()

int ReverseIndexRangeScanIterator::cmp_prev ( QUICK_RANGE *  range )

private

Init()

bool ReverseIndexRangeScanIterator::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.

quick_range_rev_seq_init()

range_seq_t ReverseIndexRangeScanIterator::quick_range_rev_seq_init ( void *  init_param, uint  , uint    )

staticprivate

range_reads_after_key()

bool ReverseIndexRangeScanIterator::range_reads_after_key ( QUICK_RANGE *  range )

private

Read()

int ReverseIndexRangeScanIterator::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.

Member Data Documentation

column_bitmap

MY_BITMAP ReverseIndexRangeScanIterator::column_bitmap

private

current_range_idx

int ReverseIndexRangeScanIterator::current_range_idx

private

inited

bool ReverseIndexRangeScanIterator::inited = false

private

key_part_info

KEY_PART_INFO* ReverseIndexRangeScanIterator::key_part_info

private

last_range

QUICK_RANGE* ReverseIndexRangeScanIterator::last_range

private

m_examined_rows

ha_rows* ReverseIndexRangeScanIterator::m_examined_rows

private

m_expected_rows

ha_rows ReverseIndexRangeScanIterator::m_expected_rows

private

m_index

const uint ReverseIndexRangeScanIterator::m_index

private

m_mrr_flags

uint ReverseIndexRangeScanIterator::m_mrr_flags

private

m_using_extended_key_parts

bool ReverseIndexRangeScanIterator::m_using_extended_key_parts {false}

private

mem_root

MEM_ROOT* ReverseIndexRangeScanIterator::mem_root

private

qr_traversal_ctx

QUICK_RANGE_SEQ_CTX ReverseIndexRangeScanIterator::qr_traversal_ctx

private

ranges

Bounds_checked_array<QUICK_RANGE *> ReverseIndexRangeScanIterator::ranges

private

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

• sql/range_optimizer/reverse_index_range_scan.h
• sql/range_optimizer/reverse_index_range_scan.cc