HashJoinChunk Class Reference

#include <hash_join_chunk.h>

Public Member Functions
	HashJoinChunk ()=default
	HashJoinChunk (HashJoinChunk &&other)
	HashJoinChunk (const HashJoinChunk &obj)=delete
HashJoinChunk &	operator= (HashJoinChunk &&other)
	~HashJoinChunk ()
bool	Init (const pack_rows::TableCollection &tables, bool uses_match_flags=false)
	Initialize this HashJoinChunk. More...
ha_rows	NumRows () const
void	SetNumRows (ha_rows no)
	Set the number of rows we currently care about in this chunk. More...
bool	WriteRowToChunk (String *buffer, bool matched, size_t file_set_no=std::numeric_limits< size_t >::max())
	Write a row to the HashJoinChunk. More...
bool	LoadRowFromChunk (String *buffer, bool *matched, size_t *file_set_no=nullptr)
	Read a row from the HashJoinChunk and put it in the record buffer. More...
bool	Rewind ()
	Flush the file buffer, and prepare the file for reading. More...
bool	SetAppend ()
	Switch from reading to writing, saving current read position m_last_read_pos. More...
bool	ContinueRead ()
	Switch from writing to reading, saving current write position in m_last_write_pos. More...

Private Attributes
pack_rows::TableCollection	m_tables
ha_rows	m_num_rows {0}
IO_CACHE	m_file
bool	m_uses_match_flags {false}
size_t	m_last_write_pos {0}
size_t	m_last_read_pos {0}

Constructor & Destructor Documentation

HashJoinChunk() [1/3]

HashJoinChunk::HashJoinChunk ( )

default

HashJoinChunk() [2/3]

HashJoinChunk::HashJoinChunk

(

HashJoinChunk &&

other

)

HashJoinChunk() [3/3]

HashJoinChunk::HashJoinChunk ( const HashJoinChunk &  obj )

delete

~HashJoinChunk()

HashJoinChunk::~HashJoinChunk

(

)

Member Function Documentation

ContinueRead()

bool HashJoinChunk::ContinueRead

(

)

Switch from writing to reading, saving current write position in m_last_write_pos.

Continue reading from m_last_read_pos.

Return values

true

on error

Init()

bool HashJoinChunk::Init	(	const pack_rows::TableCollection &	tables,
		bool	uses_match_flags = false
	)

Initialize this HashJoinChunk.

Parameters

tables	The tables to store row data from. Which column we store in the chunk file is determined by each tables read set.
uses_match_flags	Whether each row should be prefixed with a match flag, saying whether the row had a matching row.

Returns

true if the initialization failed.

LoadRowFromChunk()

bool HashJoinChunk::LoadRowFromChunk	(	String *	buffer,
		bool *	matched,
		size_t *	file_set_no = nullptr
	)

Read a row from the HashJoinChunk and put it in the record buffer.

The function will read a row from file on disk and put it in the record buffers (table->record[0]) in the provided tables. The file on disk should already be pointing to the start of a row.

Parameters

	buffer	a buffer that is used when copying data from the chunk file to the tables. Note that any existing data in "buffer" is overwritten.
[out]	matched	whether this row has seen a matching row from the other input. The flag is only restored if 'm_uses_match_flags' is set, and if the row comes from the probe input.
	file_set_no	Used by set operations only: the zero based chunk file set number. If not nullptr, set this to current set file number. Note: If WriteRowToChunk used a non ignorable file_set_no, it is expected that a non nullptr value be provided here for reading of rows to proceed correctly.

Return values

true

on error.

NumRows()

ha_rows HashJoinChunk::NumRows ( ) const

inline

Returns

the number of rows in this chunk

operator=()

HashJoinChunk & HashJoinChunk::operator=

(

HashJoinChunk &&

other

)

Rewind()

bool HashJoinChunk::Rewind

(

)

Flush the file buffer, and prepare the file for reading.

Return values

true

on error

SetAppend()

bool HashJoinChunk::SetAppend

(

)

Switch from reading to writing, saving current read position m_last_read_pos.

Continue writing from m_last_write_pos.

Return values

true

on error

SetNumRows()

void HashJoinChunk::SetNumRows ( ha_rows  no )

inline

Set the number of rows we currently care about in this chunk.

Used to keep track of number of rows written from a certain point in time (the counter is incremented by writing).

Parameters

no	the number to set the counter to

WriteRowToChunk()

bool HashJoinChunk::WriteRowToChunk	(	String *	buffer,
		bool	matched,
		size_t	file_set_no = std::numeric_limits<size_t>::max()
	)

Write a row to the HashJoinChunk.

Read the row that lies in the record buffer (record[0]) of the given tables and write it out to the underlying file. If the QEP_TAB signals that the row ID should be kept, it is also written out. Note that TABLE::read_set is used to signal which columns that should be written to the chunk.

Parameters

buffer	a buffer that is used when copying data from the tables to the chunk file. Note that any existing data in "buffer" is overwritten.
matched	whether this row has seen a matching row from the other input. The flag is only written if 'm_uses_match_flags' is set, and if the row comes from the probe input.
file_set_no	Used by set operations only: the zero based chunk file set number. If equal to std::numeric_limits<size_t>::max(), ignore ( default value).

Return values

true

on error.

Member Data Documentation

m_file

IO_CACHE HashJoinChunk::m_file

private

m_last_read_pos

size_t HashJoinChunk::m_last_read_pos {0}

private

m_last_write_pos

size_t HashJoinChunk::m_last_write_pos {0}

private

m_num_rows

ha_rows HashJoinChunk::m_num_rows {0}

private

m_tables

pack_rows::TableCollection HashJoinChunk::m_tables

private

m_uses_match_flags

bool HashJoinChunk::m_uses_match_flags {false}

private

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

• sql/iterators/hash_join_chunk.h
• sql/iterators/hash_join_chunk.cc