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1006 lines
35 KiB
1006 lines
35 KiB
3 months ago
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/* Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/*
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Function to handle quick removal of duplicates
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This code is used when doing multi-table deletes to find the rows in
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reference tables that needs to be deleted.
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The basic idea is as follows:
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Store first all strings in a binary tree, ignoring duplicates.
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When the tree uses more memory than 'max_heap_table_size',
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write the tree (in sorted order) out to disk and start with a new tree.
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When all data has been generated, merge the trees (removing any found
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duplicates).
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The unique entries will be returned in sort order, to ensure that we do the
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deletes in disk order.
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*/
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#include "sql/uniques.h" // Unique
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#include <string.h>
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#include <algorithm>
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#include <atomic>
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#include <cmath>
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#include <vector>
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#include "my_base.h"
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#include "my_compiler.h"
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#include "my_dbug.h"
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#include "my_io.h"
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#include "my_tree.h" // element_count
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#include "mysql/psi/mysql_file.h"
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#include "mysql/psi/psi_base.h"
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#include "mysql/service_mysql_alloc.h"
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#include "priority_queue.h"
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#include "sql/field.h" // Field
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#include "sql/handler.h" // handler
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#include "sql/malloc_allocator.h"
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#include "sql/merge_many_buff.h"
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#include "sql/mysqld.h" // mysql_tmpdir
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#include "sql/opt_costmodel.h"
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#include "sql/psi_memory_key.h"
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#include "sql/sql_base.h" // TEMP_PREFIX
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#include "sql/sql_class.h"
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#include "sql/sql_const.h"
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#include "sql/sql_executor.h" // check_unique_constraint
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#include "sql/sql_sort.h"
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#include "sql/sql_tmp_table.h" // create_duplicate_weedout_tmp_table
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#include "sql/table.h"
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namespace {
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struct Merge_chunk_compare_context {
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qsort2_cmp key_compare;
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const void *key_compare_arg;
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};
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class Uniq_param {
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public:
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uint rec_length; // Length of sorted records.
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uint max_keys_per_buffer; // Max keys / buffer.
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ha_rows max_rows; // Select limit, or HA_POS_ERROR if unlimited.
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uchar *unique_buff;
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bool not_killable;
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// The fields below are used only by Unique class.
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Merge_chunk_compare_context cmp_context;
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typedef int (*chunk_compare_fun)(Merge_chunk_compare_context *ctx,
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uchar *arg1, uchar *arg2);
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chunk_compare_fun compare;
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Uniq_param() { memset(this, 0, sizeof(*this)); }
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// Not copyable
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Uniq_param(const Uniq_param &) = delete;
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Uniq_param &operator=(const Uniq_param &) = delete;
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};
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} // namespace
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/**
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Read data to buffer.
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@returns
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(uint)-1 if something goes wrong
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*/
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static uint uniq_read_to_buffer(IO_CACHE *fromfile, Merge_chunk *merge_chunk,
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Uniq_param *param) {
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DBUG_TRACE;
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const uint rec_length = param->rec_length;
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const ha_rows count =
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std::min(merge_chunk->max_keys(), merge_chunk->rowcount());
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if (count) {
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const size_t bytes_to_read = rec_length * static_cast<size_t>(count);
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DBUG_PRINT("info", ("uniq_read_to_buffer %p at file_pos %llu bytes %llu",
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merge_chunk,
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static_cast<ulonglong>(merge_chunk->file_position()),
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static_cast<ulonglong>(bytes_to_read)));
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if (mysql_file_pread(fromfile->file, merge_chunk->buffer_start(),
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bytes_to_read, merge_chunk->file_position(), MYF_RW))
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return (uint)-1; /* purecov: inspected */
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merge_chunk->init_current_key();
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merge_chunk->advance_file_position(bytes_to_read);
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merge_chunk->decrement_rowcount(count);
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merge_chunk->set_mem_count(count);
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return bytes_to_read;
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}
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return 0;
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} /* uniq_read_to_buffer */
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/**
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Merge buffers to one buffer.
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@param thd
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@param param Sort parameter
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@param from_file File with source data (Merge_chunks point to this file)
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@param to_file File to write the sorted result data.
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@param sort_buffer Buffer for data to store up to MERGEBUFF2 sort keys.
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@param [out] last_chunk Store here Merge_chunk describing data written to
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to_file.
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@param chunk_array Array of chunks to merge.
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@param flag 0 - write full record, 1 - write addon/ref
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@returns
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0 OK
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@returns
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other error
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*/
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static int merge_buffers(THD *thd, Uniq_param *param, IO_CACHE *from_file,
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IO_CACHE *to_file, Sort_buffer sort_buffer,
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Merge_chunk *last_chunk, Merge_chunk_array chunk_array,
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int flag MY_ATTRIBUTE((unused))) {
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int error = 0;
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uint rec_length;
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ha_rows maxcount;
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ha_rows max_rows, org_max_rows;
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my_off_t to_start_filepos;
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uchar *strpos;
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Merge_chunk *merge_chunk;
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Uniq_param::chunk_compare_fun cmp;
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Merge_chunk_compare_context *first_cmp_arg;
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DBUG_TRACE;
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thd->inc_status_sort_merge_passes();
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rec_length = param->rec_length;
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const uint offset = 0;
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maxcount = (param->max_keys_per_buffer / chunk_array.size());
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to_start_filepos = my_b_tell(to_file);
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strpos = sort_buffer.array();
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org_max_rows = max_rows = param->max_rows;
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/* The following will fire if there is not enough space in sort_buffer */
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DBUG_ASSERT(maxcount != 0);
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DBUG_ASSERT(param->unique_buff != nullptr);
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cmp = param->compare;
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first_cmp_arg = ¶m->cmp_context;
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auto greater = [&cmp, &first_cmp_arg](const Merge_chunk *a,
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const Merge_chunk *b) {
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return cmp(first_cmp_arg, a->current_key(), b->current_key()) > 0;
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};
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Priority_queue<Merge_chunk *,
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std::vector<Merge_chunk *, Malloc_allocator<Merge_chunk *>>,
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decltype(greater)>
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queue(greater,
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Malloc_allocator<Merge_chunk *>(key_memory_Filesort_info_merge));
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if (queue.reserve(chunk_array.size())) return 1;
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for (merge_chunk = chunk_array.begin(); merge_chunk != chunk_array.end();
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merge_chunk++) {
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merge_chunk->set_buffer(
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strpos, strpos + (sort_buffer.size() / (chunk_array.size())));
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merge_chunk->set_max_keys(maxcount);
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uint bytes_read = uniq_read_to_buffer(from_file, merge_chunk, param);
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if (static_cast<int>(bytes_read) == -1) return -1; /* purecov: inspected */
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strpos += bytes_read;
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merge_chunk->set_buffer_end(strpos);
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// If less data in buffers than expected
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merge_chunk->set_max_keys(merge_chunk->mem_count());
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(void)queue.push(merge_chunk);
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}
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{
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/*
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Called by Unique::get()
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Copy the first argument to param->unique_buff for unique removal.
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Store it also in 'to_file'.
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*/
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merge_chunk = queue.top();
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memcpy(param->unique_buff, merge_chunk->current_key(), rec_length);
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if (my_b_write(to_file, merge_chunk->current_key(), rec_length)) {
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return 1; /* purecov: inspected */
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}
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merge_chunk->advance_current_key(rec_length);
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merge_chunk->decrement_mem_count();
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if (--max_rows == 0) {
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error = 0; /* purecov: inspected */
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goto end; /* purecov: inspected */
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}
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// The top chunk may actually contain only a single element
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if (merge_chunk->mem_count() == 0) {
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if (!(error = (int)uniq_read_to_buffer(from_file, merge_chunk, param))) {
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queue.pop();
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reuse_freed_buff(merge_chunk, &queue);
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} else if (error == -1)
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return error;
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}
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queue.update_top(); // Top element has been used
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}
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while (queue.size() > 1) {
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if (thd->killed && !param->not_killable) {
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return 1; /* purecov: inspected */
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}
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for (;;) {
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merge_chunk = queue.top();
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{
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uchar *current_key = merge_chunk->current_key();
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if (!(*cmp)(first_cmp_arg, param->unique_buff, current_key))
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goto skip_duplicate;
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memcpy(param->unique_buff, merge_chunk->current_key(), rec_length);
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}
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{
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const uint bytes_to_write = param->rec_length;
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DBUG_PRINT("info", ("write record at %llu len %u", my_b_tell(to_file),
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bytes_to_write));
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if (my_b_write(to_file, merge_chunk->current_key() + offset,
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bytes_to_write)) {
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return 1; /* purecov: inspected */
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}
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if (--max_rows == 0) {
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error = 0; /* purecov: inspected */
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goto end; /* purecov: inspected */
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}
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}
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skip_duplicate:
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merge_chunk->advance_current_key(rec_length);
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merge_chunk->decrement_mem_count();
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if (0 == merge_chunk->mem_count()) {
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if (!(error =
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(int)uniq_read_to_buffer(from_file, merge_chunk, param))) {
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queue.pop();
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reuse_freed_buff(merge_chunk, &queue);
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break; /* One buffer has been removed */
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} else if (error == -1)
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return error; /* purecov: inspected */
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}
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/*
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The Merge_chunk at the queue's top had one of its keys consumed, thus
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it may now rank differently in the comparison order of the queue, so:
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*/
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queue.update_top();
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}
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}
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merge_chunk = queue.top();
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merge_chunk->set_buffer(sort_buffer.array(),
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sort_buffer.array() + sort_buffer.size());
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merge_chunk->set_max_keys(param->max_keys_per_buffer);
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/*
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As we know all entries in the buffer are unique, we only have to
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check if the first one is the same as the last one we wrote
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*/
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{
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uchar *current_key = merge_chunk->current_key();
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if (!(*cmp)(first_cmp_arg, param->unique_buff, current_key)) {
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merge_chunk->advance_current_key(rec_length); // Remove duplicate
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merge_chunk->decrement_mem_count();
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}
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}
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do {
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if (merge_chunk->mem_count() > max_rows) {
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merge_chunk->set_mem_count(max_rows); /* Don't write too many records */
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merge_chunk->set_rowcount(0); /* Don't read more */
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}
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max_rows -= merge_chunk->mem_count();
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for (uint ix = 0; ix < merge_chunk->mem_count(); ++ix) {
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const uint bytes_to_write = param->rec_length;
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if (my_b_write(to_file, merge_chunk->current_key() + offset,
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bytes_to_write)) {
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return 1; /* purecov: inspected */
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}
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merge_chunk->advance_current_key(rec_length);
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}
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} while ((error = (int)uniq_read_to_buffer(from_file, merge_chunk, param)) !=
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-1 &&
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error != 0);
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end:
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last_chunk->set_rowcount(std::min(org_max_rows - max_rows, param->max_rows));
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last_chunk->set_file_position(to_start_filepos);
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return error;
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} /* merge_buffers */
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int unique_write_to_file(void *v_key, element_count, void *v_unique) {
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uchar *key = static_cast<uchar *>(v_key);
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Unique *unique = static_cast<Unique *>(v_unique);
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||
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/*
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||
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Use unique->size (size of element stored in the tree) and not
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unique->tree.size_of_element. The latter is different from unique->size
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||
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when tree implementation chooses to store pointer to key in TREE_ELEMENT
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(instead of storing the element itself there)
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||
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*/
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return my_b_write(&unique->file, key, unique->size) ? 1 : 0;
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}
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int unique_write_to_ptrs(void *v_key, element_count, void *v_unique) {
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||
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uchar *key = static_cast<uchar *>(v_key);
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||
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Unique *unique = static_cast<Unique *>(v_unique);
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||
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memcpy(unique->record_pointers, key, unique->size);
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||
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unique->record_pointers += unique->size;
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||
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return 0;
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||
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}
|
||
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|
||
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Unique::Unique(qsort2_cmp comp_func, void *comp_func_fixed_arg, uint size_arg,
|
||
|
|
ulonglong max_in_memory_size_arg)
|
||
|
|
: file_ptrs(PSI_INSTRUMENT_ME),
|
||
|
|
max_elements(0),
|
||
|
|
max_in_memory_size(max_in_memory_size_arg),
|
||
|
|
record_pointers(NULL),
|
||
|
|
size(size_arg),
|
||
|
|
elements(0) {
|
||
|
|
my_b_clear(&file);
|
||
|
|
init_tree(&tree, /* default_alloc_size */ 0,
|
||
|
|
/* memory_limit */ 0, size, comp_func,
|
||
|
|
/* with_delete */ false,
|
||
|
|
/* free_element */ nullptr, comp_func_fixed_arg);
|
||
|
|
/*
|
||
|
|
If you change the following, change it in get_max_elements function, too.
|
||
|
|
*/
|
||
|
|
max_elements =
|
||
|
|
(ulong)(max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT) + size));
|
||
|
|
(void)open_cached_file(&file, mysql_tmpdir, TEMP_PREFIX, DISK_BUFFER_SIZE,
|
||
|
|
MYF(MY_WME));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
Calculate log2(n!)
|
||
|
|
|
||
|
|
Stirling's approximate formula is used:
|
||
|
|
|
||
|
|
n! ~= sqrt(2*M_PI*n) * (n/M_E)^n
|
||
|
|
|
||
|
|
Derivation of formula used for calculations is as follows:
|
||
|
|
|
||
|
|
log2(n!) = log2(sqrt(2*M_PI*n)*(n/M_E)^n)
|
||
|
|
|
||
|
|
= log2(2*M_PI*n)/2 + n*log2(n/M_E)
|
||
|
|
|
||
|
|
= log2(2*M_PI)/2 + log2(n)/2 + n * (log2(n) - M_LOG2E);
|
||
|
|
|
||
|
|
@param n the number to calculate log2(n!) for
|
||
|
|
|
||
|
|
@return log2(n!) for the function argument
|
||
|
|
*/
|
||
|
|
|
||
|
|
static inline double log2_n_fact(ulong n) {
|
||
|
|
/*
|
||
|
|
Stirling's approximation produces a small negative value when n is
|
||
|
|
1 so we handle this as a special case in order to avoid negative
|
||
|
|
numbers in estimates. For n equal to 0, the formula below will
|
||
|
|
produce NaN. Since 0! by definition is 1, we return 0 for this
|
||
|
|
case too.
|
||
|
|
*/
|
||
|
|
if (n <= 1) return 0.0;
|
||
|
|
|
||
|
|
const auto log2_n = std::log2(n);
|
||
|
|
return std::log2(2 * M_PI) / 2 + log2_n / 2 + n * (log2_n - M_LOG2E);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Calculate cost of merge_buffers function call for given sequence of
|
||
|
|
input stream lengths and store the number of rows in result stream in *last.
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
get_merge_buffers_cost()
|
||
|
|
buff_elems Array of #s of elements in buffers
|
||
|
|
elem_size Size of element stored in buffer
|
||
|
|
first Pointer to first merged element size
|
||
|
|
last Pointer to last merged element size
|
||
|
|
|
||
|
|
RETURN
|
||
|
|
Cost of merge_buffers operation in disk seeks.
|
||
|
|
|
||
|
|
NOTES
|
||
|
|
It is assumed that no rows are eliminated during merge.
|
||
|
|
The cost is calculated as
|
||
|
|
|
||
|
|
cost(read_and_write) + cost(merge_comparisons).
|
||
|
|
|
||
|
|
All bytes in the sequences is read and written back during merge so cost
|
||
|
|
of disk io is 2*elem_size*total_buf_elems/IO_SIZE (2 is for read + write)
|
||
|
|
|
||
|
|
For comparisons cost calculations we assume that all merged sequences have
|
||
|
|
the same length, so each of total_buf_size elements will be added to a sort
|
||
|
|
heap with (n_buffers-1) elements. This gives the comparison cost:
|
||
|
|
|
||
|
|
key_compare_cost(total_buf_elems * log2(n_buffers));
|
||
|
|
*/
|
||
|
|
|
||
|
|
static double get_merge_buffers_cost(Unique::Imerge_cost_buf_type buff_elems,
|
||
|
|
uint elem_size, uint first, uint last,
|
||
|
|
const Cost_model_table *cost_model) {
|
||
|
|
uint total_buf_elems = 0;
|
||
|
|
for (uint pbuf = first; pbuf <= last; pbuf++)
|
||
|
|
total_buf_elems += buff_elems[pbuf];
|
||
|
|
buff_elems[last] = total_buf_elems;
|
||
|
|
|
||
|
|
const size_t n_buffers = last - first + 1;
|
||
|
|
|
||
|
|
const double io_ops =
|
||
|
|
static_cast<double>(total_buf_elems * elem_size) / IO_SIZE;
|
||
|
|
const double io_cost = cost_model->io_block_read_cost(io_ops);
|
||
|
|
const double cpu_cost =
|
||
|
|
cost_model->key_compare_cost(total_buf_elems * std::log2(n_buffers));
|
||
|
|
|
||
|
|
return 2 * io_cost + cpu_cost;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Calculate cost of merging buffers into one in Unique::get, i.e. calculate
|
||
|
|
how long (in terms of disk seeks) the two calls
|
||
|
|
merge_many_buffs(...);
|
||
|
|
merge_buffers(...);
|
||
|
|
will take.
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
get_merge_many_buffs_cost()
|
||
|
|
buffer buffer space for temporary data, at least
|
||
|
|
Unique::get_cost_calc_buff_size bytes
|
||
|
|
maxbuffer # of full buffers
|
||
|
|
max_n_elems # of elements in first maxbuffer buffers
|
||
|
|
last_n_elems # of elements in last buffer
|
||
|
|
elem_size size of buffer element
|
||
|
|
|
||
|
|
NOTES
|
||
|
|
maxbuffer+1 buffers are merged, where first maxbuffer buffers contain
|
||
|
|
max_n_elems elements each and last buffer contains last_n_elems elements.
|
||
|
|
|
||
|
|
The current implementation does a dumb simulation of merge_many_buffs
|
||
|
|
function actions.
|
||
|
|
|
||
|
|
RETURN
|
||
|
|
Cost of merge in disk seeks.
|
||
|
|
*/
|
||
|
|
|
||
|
|
static double get_merge_many_buffs_cost(Unique::Imerge_cost_buf_type buffer,
|
||
|
|
uint maxbuffer, uint max_n_elems,
|
||
|
|
uint last_n_elems, int elem_size,
|
||
|
|
const Cost_model_table *cost_model) {
|
||
|
|
uint i;
|
||
|
|
double total_cost = 0.0;
|
||
|
|
Unique::Imerge_cost_buf_type buff_elems =
|
||
|
|
buffer; /* #s of elements in each of merged sequences */
|
||
|
|
|
||
|
|
/*
|
||
|
|
Set initial state: first maxbuffer sequences contain max_n_elems elements
|
||
|
|
each, last sequence contains last_n_elems elements.
|
||
|
|
*/
|
||
|
|
for (i = 0; i < maxbuffer; i++) buff_elems[i] = max_n_elems;
|
||
|
|
buff_elems[maxbuffer] = last_n_elems;
|
||
|
|
|
||
|
|
/*
|
||
|
|
Do it exactly as merge_many_buff function does, calling
|
||
|
|
get_merge_buffers_cost to get cost of merge_buffers.
|
||
|
|
*/
|
||
|
|
if (maxbuffer >= MERGEBUFF2) {
|
||
|
|
while (maxbuffer >= MERGEBUFF2) {
|
||
|
|
uint lastbuff = 0;
|
||
|
|
for (i = 0; i <= maxbuffer - MERGEBUFF * 3U / 2U; i += MERGEBUFF) {
|
||
|
|
total_cost += get_merge_buffers_cost(buff_elems, elem_size, i,
|
||
|
|
i + MERGEBUFF - 1, cost_model);
|
||
|
|
lastbuff++;
|
||
|
|
}
|
||
|
|
total_cost += get_merge_buffers_cost(buff_elems, elem_size, i, maxbuffer,
|
||
|
|
cost_model);
|
||
|
|
maxbuffer = lastbuff;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Simulate final merge_buff call. */
|
||
|
|
total_cost +=
|
||
|
|
get_merge_buffers_cost(buff_elems, elem_size, 0, maxbuffer, cost_model);
|
||
|
|
return total_cost;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Calculate cost of using Unique for processing nkeys elements of size
|
||
|
|
key_size using max_in_memory_size memory.
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
Unique::get_use_cost()
|
||
|
|
buffer space for temporary data, use Unique::get_cost_calc_buff_size
|
||
|
|
to get # bytes needed.
|
||
|
|
nkeys #of elements in Unique
|
||
|
|
key_size size of each elements in bytes
|
||
|
|
max_in_memory_size amount of memory Unique will be allowed to use
|
||
|
|
|
||
|
|
RETURN
|
||
|
|
Cost in disk seeks.
|
||
|
|
|
||
|
|
NOTES
|
||
|
|
cost(using_unqiue) =
|
||
|
|
cost(create_trees) + (see #1)
|
||
|
|
cost(merge) + (see #2)
|
||
|
|
cost(read_result) (see #3)
|
||
|
|
|
||
|
|
1. Cost of trees creation
|
||
|
|
For each Unique::put operation there will be 2*log2(n+1) elements
|
||
|
|
comparisons, where n runs from 1 tree_size (we assume that all added
|
||
|
|
elements are different). Together this gives:
|
||
|
|
|
||
|
|
n_compares = 2*(log2(2) + log2(3) + ... + log2(N+1)) = 2*log2((N+1)!)
|
||
|
|
|
||
|
|
then cost(tree_creation) = key_compare_cost(n_compares);
|
||
|
|
|
||
|
|
Total cost of creating trees:
|
||
|
|
(n_trees - 1)*max_size_tree_cost + non_max_size_tree_cost.
|
||
|
|
|
||
|
|
Approximate value of log2(N!) is calculated by log2_n_fact function.
|
||
|
|
|
||
|
|
2. Cost of merging.
|
||
|
|
If only one tree is created by Unique no merging will be necessary.
|
||
|
|
Otherwise, we model execution of merge_many_buff function and count
|
||
|
|
#of merges. (The reason behind this is that number of buffers is small,
|
||
|
|
while size of buffers is big and we don't want to loose precision with
|
||
|
|
O(x)-style formula)
|
||
|
|
|
||
|
|
3. If only one tree is created by Unique no disk io will happen.
|
||
|
|
Otherwise, ceil(key_len*n_keys) disk seeks are necessary. We assume
|
||
|
|
these will be random seeks.
|
||
|
|
*/
|
||
|
|
|
||
|
|
double Unique::get_use_cost(Imerge_cost_buf_type buffer, uint nkeys,
|
||
|
|
uint key_size, ulonglong max_in_memory_size,
|
||
|
|
const Cost_model_table *cost_model) {
|
||
|
|
ulong max_elements_in_tree;
|
||
|
|
ulong last_tree_elems;
|
||
|
|
int n_full_trees; /* number of trees in unique - 1 */
|
||
|
|
|
||
|
|
max_elements_in_tree =
|
||
|
|
((ulong)max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT) + key_size));
|
||
|
|
|
||
|
|
n_full_trees = nkeys / max_elements_in_tree;
|
||
|
|
last_tree_elems = nkeys % max_elements_in_tree;
|
||
|
|
|
||
|
|
/* Calculate cost of creating trees */
|
||
|
|
double n_compares = 2 * log2_n_fact(last_tree_elems + 1);
|
||
|
|
if (n_full_trees)
|
||
|
|
n_compares += n_full_trees * log2_n_fact(max_elements_in_tree + 1);
|
||
|
|
double result = cost_model->key_compare_cost(n_compares);
|
||
|
|
|
||
|
|
DBUG_PRINT("info",
|
||
|
|
("unique trees sizes: %u=%u*%lu + %lu", nkeys, n_full_trees,
|
||
|
|
n_full_trees ? max_elements_in_tree : 0, last_tree_elems));
|
||
|
|
|
||
|
|
if (!n_full_trees) return result;
|
||
|
|
|
||
|
|
/*
|
||
|
|
There is more then one tree and merging is necessary.
|
||
|
|
First, add cost of writing all trees to disk, assuming that all disk
|
||
|
|
writes are sequential.
|
||
|
|
*/
|
||
|
|
result += cost_model->disk_seek_base_cost() * n_full_trees *
|
||
|
|
ceil(((double)key_size) * max_elements_in_tree / IO_SIZE);
|
||
|
|
result += cost_model->disk_seek_base_cost() *
|
||
|
|
ceil(((double)key_size) * last_tree_elems / IO_SIZE);
|
||
|
|
|
||
|
|
/* Cost of merge */
|
||
|
|
double merge_cost =
|
||
|
|
get_merge_many_buffs_cost(buffer, n_full_trees, max_elements_in_tree,
|
||
|
|
last_tree_elems, key_size, cost_model);
|
||
|
|
if (merge_cost < 0.0) return merge_cost;
|
||
|
|
|
||
|
|
result += merge_cost;
|
||
|
|
/*
|
||
|
|
Add cost of reading the resulting sequence, assuming there were no
|
||
|
|
duplicate elements.
|
||
|
|
*/
|
||
|
|
const double n_blocks = ceil((double)key_size * nkeys / IO_SIZE);
|
||
|
|
result += cost_model->io_block_read_cost(n_blocks);
|
||
|
|
|
||
|
|
return result;
|
||
|
|
}
|
||
|
|
|
||
|
|
Unique::~Unique() {
|
||
|
|
close_cached_file(&file);
|
||
|
|
delete_tree(&tree);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Write tree to disk; clear tree */
|
||
|
|
bool Unique::flush() {
|
||
|
|
Merge_chunk file_ptr;
|
||
|
|
elements += tree.elements_in_tree;
|
||
|
|
file_ptr.set_rowcount(tree.elements_in_tree);
|
||
|
|
file_ptr.set_file_position(my_b_tell(&file));
|
||
|
|
|
||
|
|
if (tree_walk(&tree, unique_write_to_file, this, left_root_right) ||
|
||
|
|
file_ptrs.push_back(file_ptr))
|
||
|
|
return true; /* purecov: inspected */
|
||
|
|
delete_tree(&tree);
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Clear the tree and the file.
|
||
|
|
You must call reset() if you want to reuse Unique after walk().
|
||
|
|
*/
|
||
|
|
|
||
|
|
void Unique::reset() {
|
||
|
|
reset_tree(&tree);
|
||
|
|
/*
|
||
|
|
If elements != 0, some trees were stored in the file (see how
|
||
|
|
flush() works). Note, that we can not count on my_b_tell(&file) == 0
|
||
|
|
here, because it can return 0 right after walk(), and walk() does not
|
||
|
|
reset any Unique member.
|
||
|
|
*/
|
||
|
|
if (elements) {
|
||
|
|
file_ptrs.clear();
|
||
|
|
reinit_io_cache(&file, WRITE_CACHE, 0L, 0, 1);
|
||
|
|
}
|
||
|
|
/*
|
||
|
|
If table is used - finish index access and delete all records.
|
||
|
|
use_table is set to false, so on the next run the memory tree will be used
|
||
|
|
again at the beginning.
|
||
|
|
*/
|
||
|
|
elements = 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
The comparison function, used by the Priority_queue in merge_buffers()
|
||
|
|
When the called from Uniques::get() must use comparison function of
|
||
|
|
Uniques::tree, but compare members of struct Merge_chunk.
|
||
|
|
*/
|
||
|
|
|
||
|
|
static int merge_chunk_compare(Merge_chunk_compare_context *ctx,
|
||
|
|
uchar *key_ptr1, uchar *key_ptr2) {
|
||
|
|
return ctx->key_compare(ctx->key_compare_arg, key_ptr1, key_ptr2);
|
||
|
|
}
|
||
|
|
|
||
|
|
namespace {
|
||
|
|
|
||
|
|
struct Merge_chunk_less {
|
||
|
|
Merge_chunk_less(const Merge_chunk_compare_context context)
|
||
|
|
: m_context(context) {}
|
||
|
|
bool operator()(Merge_chunk *a, Merge_chunk *b) {
|
||
|
|
return m_context.key_compare(m_context.key_compare_arg, a->current_key(),
|
||
|
|
b->current_key()) > 0;
|
||
|
|
}
|
||
|
|
Merge_chunk_compare_context m_context;
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace
|
||
|
|
|
||
|
|
/*
|
||
|
|
DESCRIPTION
|
||
|
|
|
||
|
|
Function is very similar to merge_buffers, but instead of writing sorted
|
||
|
|
unique keys to the output file, it invokes walk_action for each key.
|
||
|
|
This saves I/O if you need to pass through all unique keys only once.
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
merge_walk()
|
||
|
|
All params are 'IN' (but see comment for begin, end):
|
||
|
|
merge_buffer buffer to perform cached piece-by-piece loading
|
||
|
|
of trees; initially the buffer is empty
|
||
|
|
merge_buffer_size size of merge_buffer. Must be aligned with
|
||
|
|
key_length
|
||
|
|
key_length size of tree element; key_length * (end - begin)
|
||
|
|
must be less or equal than merge_buffer_size.
|
||
|
|
begin pointer to Merge_chunk struct for the first tree.
|
||
|
|
end pointer to Merge_chunk struct for the last tree;
|
||
|
|
end > begin and [begin, end) form a consecutive
|
||
|
|
range. Merge_chunks structs in that range are used and
|
||
|
|
overwritten in merge_walk().
|
||
|
|
walk_action element visitor. Action is called for each unique
|
||
|
|
key.
|
||
|
|
walk_action_arg argument to walk action. Passed to it on each call.
|
||
|
|
compare elements comparison function
|
||
|
|
compare_arg comparison function argument
|
||
|
|
file file with all trees dumped. Trees in the file
|
||
|
|
must contain sorted unique values. Cache must be
|
||
|
|
initialized in read mode.
|
||
|
|
RETURN VALUE
|
||
|
|
0 ok
|
||
|
|
<> 0 error
|
||
|
|
*/
|
||
|
|
|
||
|
|
static bool merge_walk(uchar *merge_buffer, size_t merge_buffer_size,
|
||
|
|
size_t key_length, Merge_chunk *begin, Merge_chunk *end,
|
||
|
|
tree_walk_action walk_action, void *walk_action_arg,
|
||
|
|
qsort2_cmp compare, const void *compare_arg,
|
||
|
|
IO_CACHE *file) {
|
||
|
|
if (end <= begin ||
|
||
|
|
merge_buffer_size < (ulong)(key_length * (end - begin + 1)))
|
||
|
|
return 1;
|
||
|
|
|
||
|
|
Merge_chunk_compare_context compare_context = {compare, compare_arg};
|
||
|
|
Priority_queue<Merge_chunk *,
|
||
|
|
std::vector<Merge_chunk *, Malloc_allocator<Merge_chunk *>>,
|
||
|
|
Merge_chunk_less>
|
||
|
|
queue((Merge_chunk_less(compare_context)),
|
||
|
|
(Malloc_allocator<Merge_chunk *>(key_memory_Unique_merge_buffer)));
|
||
|
|
if (queue.reserve(end - begin)) return 1;
|
||
|
|
|
||
|
|
/* we need space for one key when a piece of merge buffer is re-read */
|
||
|
|
merge_buffer_size -= key_length;
|
||
|
|
uchar *save_key_buff = merge_buffer + merge_buffer_size;
|
||
|
|
uint max_key_count_per_piece =
|
||
|
|
(uint)(merge_buffer_size / (end - begin) / key_length);
|
||
|
|
/* if piece_size is aligned reuse_freed_buffer will always hit */
|
||
|
|
size_t piece_size = max_key_count_per_piece * key_length;
|
||
|
|
uint bytes_read; /* to hold return value of uniq_read_to_buffer */
|
||
|
|
Merge_chunk *top;
|
||
|
|
int res = 1;
|
||
|
|
|
||
|
|
// uniq_read_to_buffer() needs only rec_length.
|
||
|
|
Uniq_param uniq_param;
|
||
|
|
uniq_param.rec_length = key_length;
|
||
|
|
|
||
|
|
/*
|
||
|
|
Invariant: queue must contain top element from each tree, until a tree
|
||
|
|
is not completely walked through.
|
||
|
|
Here we're forcing the invariant, inserting one element from each tree
|
||
|
|
to the queue.
|
||
|
|
*/
|
||
|
|
for (top = begin; top != end; ++top) {
|
||
|
|
top->set_buffer_start(merge_buffer + (top - begin) * piece_size);
|
||
|
|
top->set_buffer_end(top->buffer_start() + piece_size);
|
||
|
|
top->set_max_keys(max_key_count_per_piece);
|
||
|
|
bytes_read = uniq_read_to_buffer(file, top, &uniq_param);
|
||
|
|
if (bytes_read == (uint)(-1)) goto end;
|
||
|
|
DBUG_ASSERT(bytes_read);
|
||
|
|
queue.push(top);
|
||
|
|
}
|
||
|
|
top = queue.top();
|
||
|
|
while (queue.size() > 1) {
|
||
|
|
/*
|
||
|
|
Every iteration one element is removed from the queue, and one is
|
||
|
|
inserted by the rules of the invariant. If two adjacent elements on
|
||
|
|
the top of the queue are not equal, biggest one is unique, because all
|
||
|
|
elements in each tree are unique. Action is applied only to unique
|
||
|
|
elements.
|
||
|
|
*/
|
||
|
|
void *old_key = top->current_key();
|
||
|
|
/*
|
||
|
|
read next key from the cache or from the file and push it to the
|
||
|
|
queue; this gives new top.
|
||
|
|
*/
|
||
|
|
top->advance_current_key(key_length);
|
||
|
|
top->decrement_mem_count();
|
||
|
|
if (top->mem_count())
|
||
|
|
queue.update_top();
|
||
|
|
else /* next piece should be read */
|
||
|
|
{
|
||
|
|
/* save old_key not to overwrite it in uniq_read_to_buffer */
|
||
|
|
memcpy(save_key_buff, old_key, key_length);
|
||
|
|
old_key = save_key_buff;
|
||
|
|
bytes_read = uniq_read_to_buffer(file, top, &uniq_param);
|
||
|
|
if (bytes_read == (uint)(-1))
|
||
|
|
goto end;
|
||
|
|
else if (bytes_read > 0) /* top->key, top->mem_count are reset */
|
||
|
|
queue.update_top(); /* in uniq_read_to_buffer */
|
||
|
|
else {
|
||
|
|
/*
|
||
|
|
Tree for old 'top' element is empty: remove it from the queue and
|
||
|
|
give all its memory to the nearest tree.
|
||
|
|
*/
|
||
|
|
queue.pop();
|
||
|
|
reuse_freed_buff(top, &queue);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
top = queue.top();
|
||
|
|
/* new top has been obtained; if old top is unique, apply the action */
|
||
|
|
if (compare(compare_arg, old_key, top->current_key())) {
|
||
|
|
if (walk_action(old_key, 1, walk_action_arg)) goto end;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
/*
|
||
|
|
Applying walk_action to the tail of the last tree: this is safe because
|
||
|
|
either we had only one tree in the beginning, either we work with the
|
||
|
|
last tree in the queue.
|
||
|
|
*/
|
||
|
|
do {
|
||
|
|
do {
|
||
|
|
if (walk_action(top->current_key(), 1, walk_action_arg)) goto end;
|
||
|
|
top->advance_current_key(key_length);
|
||
|
|
} while (top->decrement_mem_count());
|
||
|
|
bytes_read = uniq_read_to_buffer(file, top, &uniq_param);
|
||
|
|
if (bytes_read == (uint)(-1)) goto end;
|
||
|
|
} while (bytes_read);
|
||
|
|
res = 0;
|
||
|
|
end:
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
DESCRIPTION
|
||
|
|
Walks consecutively through all unique elements:
|
||
|
|
if all elements are in memory, then it simply invokes 'tree_walk', else
|
||
|
|
all flushed trees are loaded to memory piece-by-piece, pieces are
|
||
|
|
sorted, and action is called for each unique value.
|
||
|
|
Note: so as merging resets file_ptrs state, this method can change
|
||
|
|
internal Unique state to undefined: if you want to reuse Unique after
|
||
|
|
walk() you must call reset() first!
|
||
|
|
SYNOPSIS
|
||
|
|
Unique:walk()
|
||
|
|
All params are 'IN':
|
||
|
|
action function-visitor, typed in include/my_tree.h
|
||
|
|
function is called for each unique element
|
||
|
|
arg argument for visitor, which is passed to it on each call
|
||
|
|
RETURN VALUE
|
||
|
|
0 OK
|
||
|
|
<> 0 error
|
||
|
|
*/
|
||
|
|
|
||
|
|
bool Unique::walk(tree_walk_action action, void *walk_action_arg) {
|
||
|
|
int res;
|
||
|
|
uchar *merge_buffer;
|
||
|
|
|
||
|
|
if (elements == 0) /* the whole tree is in memory */
|
||
|
|
return tree_walk(&tree, action, walk_action_arg, left_root_right);
|
||
|
|
|
||
|
|
/* flush current tree to the file to have some memory for merge buffer */
|
||
|
|
if (flush()) return 1;
|
||
|
|
if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
|
||
|
|
return 1;
|
||
|
|
|
||
|
|
/*
|
||
|
|
Compute the size of the merge buffer used by merge_walk(). This buffer
|
||
|
|
must at least be able to store one element from each file pointer plus
|
||
|
|
one extra.
|
||
|
|
*/
|
||
|
|
const size_t min_merge_buffer_size = (file_ptrs.size() + 1) * size;
|
||
|
|
const size_t merge_buffer_size =
|
||
|
|
std::max(min_merge_buffer_size, static_cast<size_t>(max_in_memory_size));
|
||
|
|
|
||
|
|
if (!(merge_buffer = (uchar *)my_malloc(key_memory_Unique_merge_buffer,
|
||
|
|
merge_buffer_size, MYF(0))))
|
||
|
|
return 1;
|
||
|
|
res = merge_walk(merge_buffer, merge_buffer_size, size, file_ptrs.begin(),
|
||
|
|
file_ptrs.end(), action, walk_action_arg, tree.compare,
|
||
|
|
tree.custom_arg, &file);
|
||
|
|
my_free(merge_buffer);
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Modify the TABLE element so that when one calls init_records()
|
||
|
|
the rows will be read in priority order.
|
||
|
|
*/
|
||
|
|
|
||
|
|
bool Unique::get(TABLE *table) {
|
||
|
|
table->unique_result.found_records = elements + tree.elements_in_tree;
|
||
|
|
|
||
|
|
if (my_b_tell(&file) == 0) {
|
||
|
|
/* Whole tree is in memory; Don't use disk if you don't need to */
|
||
|
|
DBUG_ASSERT(table->unique_result.sorted_result == NULL);
|
||
|
|
table->unique_result.sorted_result.reset(
|
||
|
|
(uchar *)my_malloc(key_memory_Filesort_info_record_pointers,
|
||
|
|
size * tree.elements_in_tree, MYF(0)));
|
||
|
|
if ((record_pointers = table->unique_result.sorted_result.get())) {
|
||
|
|
(void)tree_walk(&tree, unique_write_to_ptrs, this, left_root_right);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
/* Not enough memory; Save the result to file && free memory used by tree */
|
||
|
|
if (flush()) return 1;
|
||
|
|
|
||
|
|
IO_CACHE *outfile = table->unique_result.io_cache;
|
||
|
|
Merge_chunk *file_ptr = file_ptrs.begin();
|
||
|
|
size_t num_chunks = file_ptrs.size();
|
||
|
|
uchar *sort_memory;
|
||
|
|
my_off_t save_pos;
|
||
|
|
bool error = 1;
|
||
|
|
|
||
|
|
/* Open cached file if it isn't open */
|
||
|
|
DBUG_ASSERT(table->unique_result.io_cache == NULL);
|
||
|
|
outfile = table->unique_result.io_cache = (IO_CACHE *)my_malloc(
|
||
|
|
key_memory_TABLE_sort_io_cache, sizeof(IO_CACHE), MYF(MY_ZEROFILL));
|
||
|
|
|
||
|
|
if (!outfile || (!my_b_inited(outfile) &&
|
||
|
|
open_cached_file(outfile, mysql_tmpdir, TEMP_PREFIX,
|
||
|
|
READ_RECORD_BUFFER, MYF(MY_WME))))
|
||
|
|
return 1;
|
||
|
|
reinit_io_cache(outfile, WRITE_CACHE, 0L, 0, 0);
|
||
|
|
|
||
|
|
Uniq_param uniq_param;
|
||
|
|
uniq_param.max_rows = elements;
|
||
|
|
uniq_param.rec_length = size;
|
||
|
|
uniq_param.max_keys_per_buffer =
|
||
|
|
static_cast<uint>(max_in_memory_size / uniq_param.rec_length);
|
||
|
|
uniq_param.not_killable = 1;
|
||
|
|
|
||
|
|
const size_t num_bytes =
|
||
|
|
(uniq_param.max_keys_per_buffer + 1) * uniq_param.rec_length;
|
||
|
|
if (!(sort_memory = (uchar *)my_malloc(key_memory_Unique_sort_buffer,
|
||
|
|
num_bytes, MYF(0))))
|
||
|
|
return 1;
|
||
|
|
uniq_param.unique_buff =
|
||
|
|
sort_memory + (uniq_param.max_keys_per_buffer * uniq_param.rec_length);
|
||
|
|
|
||
|
|
uniq_param.compare = merge_chunk_compare;
|
||
|
|
uniq_param.cmp_context.key_compare = tree.compare;
|
||
|
|
uniq_param.cmp_context.key_compare_arg = tree.custom_arg;
|
||
|
|
|
||
|
|
/* Merge the buffers to one file, removing duplicates */
|
||
|
|
if (merge_many_buff(table->in_use, &uniq_param,
|
||
|
|
Sort_buffer(sort_memory, num_bytes),
|
||
|
|
Merge_chunk_array(file_ptrs.begin(), file_ptrs.size()),
|
||
|
|
&num_chunks, &file))
|
||
|
|
goto err;
|
||
|
|
if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
|
||
|
|
goto err;
|
||
|
|
if (merge_buffers(table->in_use, &uniq_param, &file, outfile,
|
||
|
|
Sort_buffer(sort_memory, num_bytes), file_ptr,
|
||
|
|
Merge_chunk_array(file_ptr, num_chunks), 0))
|
||
|
|
goto err;
|
||
|
|
error = 0;
|
||
|
|
err:
|
||
|
|
my_free(sort_memory);
|
||
|
|
if (flush_io_cache(outfile)) error = 1;
|
||
|
|
|
||
|
|
/* Setup io_cache for reading */
|
||
|
|
save_pos = outfile->pos_in_file;
|
||
|
|
if (reinit_io_cache(outfile, READ_CACHE, 0L, 0, 0)) error = 1;
|
||
|
|
outfile->end_of_file = save_pos;
|
||
|
|
return error;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool Unique_on_insert::unique_add(void *ptr) {
|
||
|
|
Field *key = *m_table->visible_field_ptr();
|
||
|
|
if (key->store((const char *)ptr, m_size, &my_charset_bin) != TYPE_OK)
|
||
|
|
return true; /* purecov: inspected */
|
||
|
|
if (!check_unique_constraint(m_table)) return true;
|
||
|
|
uint res = m_table->file->ha_write_row(m_table->record[0]);
|
||
|
|
if (res) {
|
||
|
|
bool dup = false;
|
||
|
|
if (res == HA_ERR_FOUND_DUPP_KEY) return true;
|
||
|
|
if (create_ondisk_from_heap(m_table->in_use, m_table, res, false, &dup) ||
|
||
|
|
dup)
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
void Unique_on_insert::reset(bool reinit) {
|
||
|
|
/* Finish index access and delete all records. */
|
||
|
|
m_table->file->ha_index_or_rnd_end();
|
||
|
|
m_table->file->ha_delete_all_rows();
|
||
|
|
if (reinit) m_table->file->ha_index_init(0, true);
|
||
|
|
}
|
||
|
|
|
||
|
|
bool Unique_on_insert::init() {
|
||
|
|
// If it's first run and table haven't been created yet - create it
|
||
|
|
if (!m_table && !(m_table = create_duplicate_weedout_tmp_table(
|
||
|
|
current_thd, m_size, nullptr)))
|
||
|
|
return true; /* purecov: inspected */
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
void Unique_on_insert::cleanup() {
|
||
|
|
reset(false);
|
||
|
|
free_tmp_table(m_table->in_use, m_table);
|
||
|
|
}
|