Unique Class Reference

Unique – class for unique (removing of duplicates). More...

#include <uniques.h>

Public Member Functions
	Unique (qsort2_cmp comp_func, void *comp_func_fixed_arg, uint size_arg, ulonglong max_in_memory_size_arg)
	~Unique ()
ulong	elements_in_tree ()
bool	unique_add (void *ptr)
	Add new value to Unique. More...
bool	get (TABLE *table)
void	reset ()
bool	walk (tree_walk_action action, void *walk_action_arg)
uint	get_size () const
ulonglong	get_max_in_memory_size () const
bool	is_in_memory ()

Static Public Member Functions
static double	get_use_cost (uint nkeys, uint key_size, ulonglong max_in_memory_size, const Cost_model_table *cost_model)

Public Attributes
ulong	elements

Private Member Functions
bool	flush ()
	Flush tree to disk. More...

Private Attributes
Prealloced_array< Merge_chunk, 16 >	file_ptrs
	Array of file pointers. More...
ulong	max_elements
	Max elements in memory buffer. More...
ulonglong	max_in_memory_size
	Memory buffer size. More...
IO_CACHE	file
	Cache file for unique values retrieval of table read AM in executor. More...
TREE	tree
	Tree to filter duplicates in memory. More...
uchar *	record_pointers
uint	size
	Element size. More...

Friends
int	unique_write_to_file (void *v_key, element_count count, void *unique)
int	unique_write_to_ptrs (void *v_key, element_count count, void *unique)

Detailed Description

Unique – class for unique (removing of duplicates).

Puts all values to the TREE. If the tree becomes too big, it's dumped to the file. User can request sorted values, or just iterate through them. In the last case tree merging is performed in memory simultaneously with iteration, so it should be ~2-3x faster.

Unique values can be read only from final result (not on insert) because duplicate values can be contained in different dumped tree files.

Constructor & Destructor Documentation

Unique()

Unique::Unique	(	qsort2_cmp	comp_func,
		void *	comp_func_fixed_arg,
		uint	size_arg,
		ulonglong	max_in_memory_size_arg
	)

~Unique()

Unique::~Unique

(

)

Member Function Documentation

elements_in_tree()

ulong Unique::elements_in_tree ( )

inline

flush()

bool Unique::flush ( )

private

Flush tree to disk.

get()

bool Unique::get

(

TABLE *

table

)

get_max_in_memory_size()

ulonglong Unique::get_max_in_memory_size ( ) const

inline

get_size()

uint Unique::get_size ( ) const

inline

get_use_cost()

double Unique::get_use_cost ( uint  nkeys, uint  key_size, ulonglong  max_in_memory_size, const Cost_model_table *  cost_model  )

static

is_in_memory()

bool Unique::is_in_memory ( )

inline

reset()

void Unique::reset

(

void

)

unique_add()

bool Unique::unique_add ( void *  ptr )

inline

Add new value to Unique.

The value is inserted either to the tree, or to the duplicate weedout table, depending on the mode of operation. If tree's mem buffer is full, it's flushed to the disk.

Parameters

ptr	pointer to the binary string to insert

Returns

false error or duplicate true the value was inserted

walk()

bool Unique::walk	(	tree_walk_action	action,
		void *	walk_action_arg
	)

Friends And Related Function Documentation

unique_write_to_file

int unique_write_to_file ( void *  v_key, element_count  count, void *  unique  )

friend

unique_write_to_ptrs

int unique_write_to_ptrs ( void *  v_key, element_count  count, void *  unique  )

friend

Member Data Documentation

elements

ulong Unique::elements

file

IO_CACHE Unique::file

private

Cache file for unique values retrieval of table read AM in executor.

file_ptrs

Prealloced_array<Merge_chunk, 16> Unique::file_ptrs

private

Array of file pointers.

max_elements

ulong Unique::max_elements

private

Max elements in memory buffer.

max_in_memory_size

ulonglong Unique::max_in_memory_size

private

Memory buffer size.

record_pointers

uchar* Unique::record_pointers

private

size

uint Unique::size

private

Element size.

tree

TREE Unique::tree

private

Tree to filter duplicates in memory.

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

• sql/uniques.h
• sql/uniques.cc