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/* Copyright (c) 2001, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef UNIQUES_INCLUDED
#define UNIQUES_INCLUDED
#include <stddef.h>
#include <sys/types.h>
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_pointer_arithmetic.h"
#include "my_sys.h"
#include "my_tree.h" // TREE
#include "prealloced_array.h" // Prealloced_array
#include "sql/sql_array.h"
#include "sql/sql_sort.h" // IWYU pragma: keep
class Cost_model_table;
struct TABLE;
/**
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.
*/
class Unique {
/// Array of file pointers
Prealloced_array<Merge_chunk, 16> file_ptrs;
/// Max elements in memory buffer
ulong max_elements;
/// Memory buffer size
ulonglong max_in_memory_size;
/// Cache file for unique values retrieval of table read AM in executor
IO_CACHE file;
/// Tree to filter duplicates in memory
TREE tree;
uchar *record_pointers;
/// Flush tree to disk
bool flush();
/// Element size
uint size;
public:
ulong elements;
Unique(qsort2_cmp comp_func, void *comp_func_fixed_arg, uint size_arg,
ulonglong max_in_memory_size_arg);
~Unique();
ulong elements_in_tree() { return tree.elements_in_tree; }
/**
Add new value to Unique
@details 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.
@param ptr pointer to the binary string to insert
@returns
false error or duplicate
true the value was inserted
*/
inline bool unique_add(void *ptr) {
DBUG_TRACE;
DBUG_PRINT("info", ("tree %u - %lu", tree.elements_in_tree, max_elements));
if (tree.elements_in_tree > max_elements && flush()) return true;
return !tree_insert(&tree, ptr, 0, tree.custom_arg);
}
bool get(TABLE *table);
static double get_use_cost(uint nkeys, uint key_size,
ulonglong max_in_memory_size,
const Cost_model_table *cost_model);
void reset();
bool walk(tree_walk_action action, void *walk_action_arg);
uint get_size() const { return size; }
ulonglong get_max_in_memory_size() const { return max_in_memory_size; }
bool is_in_memory() { return elements == 0; }
friend int unique_write_to_file(void *v_key, element_count count,
void *unique);
friend int unique_write_to_ptrs(void *v_key, element_count count,
void *unique);
};
/**
Unique_on_insert -- similar to above, but rejects duplicates on insert, not
just on read of the final result.
To achieve this values are inserted into mem tmp table which uses index to
detect duplicate keys. When memory buffer is full, tmp table is dumped to a
disk-based tmp table.
*/
class Unique_on_insert {
/// Element size
uint m_size;
/// Duplicate weedout tmp table
TABLE *m_table{nullptr};
public:
Unique_on_insert(uint size) : m_size(size) {}
/**
Add row id to the filter
@param ptr pointer to the rowid
@returns
false rowid successfully inserted
true duplicate or error
*/
bool unique_add(void *ptr);
/**
Initialize duplicate filter - allocate duplicate weedout tmp table
@returns
false initialization succeeded
true an error occur
*/
bool init();
/**
Reset filter - drop all rowid records
@param reinit Whether to restart index scan
*/
void reset(bool reinit);
/**
Cleanup unique filter
*/
void cleanup();
};
#endif // UNIQUES_INCLUDED
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