Merge_chunk Struct Reference

Descriptor for a merge chunk to be sort-merged. More...

#include <sql_sort.h>

Public Member Functions
my_off_t	file_position () const
void	set_file_position (my_off_t val)
void	advance_file_position (my_off_t val)
uchar *	buffer_start ()
const uchar *	buffer_end () const
const uchar *	valid_buffer_end () const
void	set_buffer (uchar *start, uchar *end)
void	set_buffer_start (uchar *start)
void	set_buffer_end (uchar *end)
void	set_valid_buffer_end (uchar *end)
void	init_current_key ()
uchar *	current_key () const
void	advance_current_key (uint val)
void	decrement_rowcount (ha_rows val)
void	set_rowcount (ha_rows val)
ha_rows	rowcount () const
ha_rows	mem_count () const
void	set_mem_count (ha_rows val)
ha_rows	decrement_mem_count ()
ha_rows	max_keys () const
void	set_max_keys (ha_rows val)
size_t	buffer_size () const
bool	merge_freed_buff (Merge_chunk *mc) const
	Tries to merge *this with *mc, returns true if successful. More...

Private Attributes
uchar *	m_current_key = nullptr
	The current key for this chunk. More...
my_off_t	m_file_position = 0
	Current position in the file to be sorted. More...
uchar *	m_buffer_start = nullptr
	Start of main-memory buffer for this chunk. More...
uchar *	m_buffer_end = nullptr
	End of main-memory buffer for this chunk. More...
uchar *	m_valid_buffer_end
	End of actual, valid data for this chunk. More...
ha_rows	m_rowcount = 0
	Number of unread rows in this chunk. More...
ha_rows	m_mem_count = 0
	Number of rows in the main-memory buffer. More...
ha_rows	m_max_keys = 0
	If we have fixed-size rows: max number of rows in buffer. More...

Detailed Description

Descriptor for a merge chunk to be sort-merged.

A merge chunk is a sequence of pre-sorted records, written to a temporary file. A Merge_chunk instance describes where this chunk is stored in the file, and where it is located when it is in memory.

It is a POD because we read/write them from/to files (but note, only m_file_position and m_rowcount are actually used in that situation).

We have accessors (getters/setters) for all struct members.

Member Function Documentation

advance_current_key()

void Merge_chunk::advance_current_key ( uint  val )

inline

advance_file_position()

void Merge_chunk::advance_file_position ( my_off_t  val )

inline

buffer_end()

const uchar * Merge_chunk::buffer_end ( ) const

inline

buffer_size()

size_t Merge_chunk::buffer_size ( ) const

inline

buffer_start()

uchar * Merge_chunk::buffer_start ( )

inline

current_key()

uchar * Merge_chunk::current_key ( ) const

inline

decrement_mem_count()

ha_rows Merge_chunk::decrement_mem_count ( )

inline

decrement_rowcount()

void Merge_chunk::decrement_rowcount ( ha_rows  val )

inline

file_position()

my_off_t Merge_chunk::file_position ( ) const

inline

init_current_key()

void Merge_chunk::init_current_key ( )

inline

max_keys()

ha_rows Merge_chunk::max_keys ( ) const

inline

mem_count()

ha_rows Merge_chunk::mem_count ( ) const

inline

merge_freed_buff()

bool Merge_chunk::merge_freed_buff ( Merge_chunk *  mc ) const

inline

Tries to merge *this with *mc, returns true if successful.

The assumption is that *this is no longer in use, and the space it has been allocated can be handed over to a buffer which is adjacent to it.

rowcount()

ha_rows Merge_chunk::rowcount ( ) const

inline

set_buffer()

void Merge_chunk::set_buffer ( uchar *  start, uchar *  end  )

inline

set_buffer_end()

void Merge_chunk::set_buffer_end ( uchar *  end )

inline

set_buffer_start()

void Merge_chunk::set_buffer_start ( uchar *  start )

inline

set_file_position()

void Merge_chunk::set_file_position ( my_off_t  val )

inline

set_max_keys()

void Merge_chunk::set_max_keys ( ha_rows  val )

inline

set_mem_count()

void Merge_chunk::set_mem_count ( ha_rows  val )

inline

set_rowcount()

void Merge_chunk::set_rowcount ( ha_rows  val )

inline

set_valid_buffer_end()

void Merge_chunk::set_valid_buffer_end ( uchar *  end )

inline

valid_buffer_end()

const uchar * Merge_chunk::valid_buffer_end ( ) const

inline

Member Data Documentation

m_buffer_end

uchar* Merge_chunk::m_buffer_end = nullptr

private

End of main-memory buffer for this chunk.

m_buffer_start

uchar* Merge_chunk::m_buffer_start = nullptr

private

Start of main-memory buffer for this chunk.

m_current_key

uchar* Merge_chunk::m_current_key = nullptr

private

The current key for this chunk.

m_file_position

my_off_t Merge_chunk::m_file_position = 0

private

Current position in the file to be sorted.

m_max_keys

ha_rows Merge_chunk::m_max_keys = 0

private

If we have fixed-size rows: max number of rows in buffer.

m_mem_count

ha_rows Merge_chunk::m_mem_count = 0

private

Number of rows in the main-memory buffer.

m_rowcount

ha_rows Merge_chunk::m_rowcount = 0

private

Number of unread rows in this chunk.

m_valid_buffer_end

uchar* Merge_chunk::m_valid_buffer_end

private

End of actual, valid data for this chunk.

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The documentation for this struct was generated from the following file:

• sql/sql_sort.h