filesort.h File Reference

#include <stddef.h>
#include <sys/types.h>
#include "mem_root_array.h"
#include "my_base.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_table_map.h"
#include "sql/sort_param.h"

Go to the source code of this file.

Classes
class	Filesort
	Sorting related info. More...

Functions
bool	filesort (THD *thd, Filesort *filesort, RowIterator *source_iterator, table_map tables_to_get_rowid_for, ha_rows num_rows_estimate, Filesort_info *fs_info, Sort_result *sort_result, ha_rows *found_rows)
	Sort a table. More...
void	filesort_free_buffers (TABLE *table, bool full)
void	change_double_for_sort (double nr, uchar *to)
uint	sortlength (THD *thd, st_sort_field *sortorder, uint s_length)
	Declared here so we can unit test it. More...
template<bool Is_big_endian>
void	copy_integer (uchar *to, size_t to_length, const uchar *from, size_t from_length, bool is_unsigned)
	Copies an integer value to a format comparable with memcmp(). More...
bool	SortWillBeOnRowId (const TABLE *table)
static void	copy_native_longlong (uchar *to, size_t to_length, longlong val, bool is_unsigned)

Function Documentation

change_double_for_sort()

void change_double_for_sort	(	double	nr,
		uchar *	to
	)

copy_integer()

template<bool Is_big_endian>

void copy_integer	(	uchar *	to,
		size_t	to_length,
		const uchar *	from,
		size_t	from_length,
		bool	is_unsigned
	)

Copies an integer value to a format comparable with memcmp().

The format is characterized by the following:

• The sign bit goes first and is unset for negative values.
• The representation is big endian.

The function template can be instantiated to copy from little or big endian values.

Template Parameters

Is_big_endian

True if the source integer is big endian.

Parameters

to	Where to write the integer.
to_length	Size in bytes of the destination buffer.
from	Where to read the integer.
from_length	Size in bytes of the source integer
is_unsigned	True if the source integer is an unsigned value.

copy_native_longlong()

static void copy_native_longlong ( uchar *  to, size_t  to_length, longlong  val, bool  is_unsigned  )

inlinestatic

filesort()

bool filesort	(	THD *	thd,
		Filesort *	filesort,
		RowIterator *	source_iterator,
		table_map	tables_to_get_rowid_for,
		ha_rows	num_rows_estimate,
		Filesort_info *	fs_info,
		Sort_result *	sort_result,
		ha_rows *	found_rows
	)

Sort a table.

Creates a set of pointers that can be used to read the rows in sorted order. This should be done with the functions in records.cc.

The result set is stored in fs_info->io_cache or fs_info->sorted_result, or left in the main filesort buffer.

Parameters

	thd	Current thread
	filesort	How to sort the table
	source_iterator	Where to read the rows to be sorted from.
	tables_to_get_rowid_for	Which tables we are responsible for getting row IDs for. Tables in this set that are not also in "tables" are ignored.
	num_rows_estimate	How many rows source_iterator is expected to produce. Only used for whether we intend to use the priority queue optimization or not; if we estimate fewer rows than we can fit into RAM, we never use the priority queue.
	fs_info	Owns the buffers for sort_result.
	sort_result	Where to store the sort result.
[out]	found_rows	Store the number of found rows here. This is the number of found rows after applying WHERE condition.

Note

If we sort row IDs (as opposed to addon fields), filesort() will call table->prepare_for_position().

Returns

False if success, true if error

filesort_free_buffers()

void filesort_free_buffers	(	TABLE *	table,
		bool	full
	)

sortlength()

uint sortlength	(	THD *	thd,
		st_sort_field *	sortorder,
		uint	s_length
	)

Declared here so we can unit test it.

Declared here so we can unit test it.

Parameters

thd	Thread handler
sortorder	Order of items to sort
s_length	Number of items to sort

Note

sortorder->length is updated for each sort item.

Returns

Total length of sort buffer in bytes

SortWillBeOnRowId()

bool SortWillBeOnRowId

(

const TABLE *

table

)