mirror of
https://github.com/MariaDB/server.git
synced 2025-04-15 11:45:32 +02:00
466 lines
11 KiB
C++
466 lines
11 KiB
C++
/* Copyright (c) 2023 MariaDB Corporation
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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 as published by
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the Free Software Foundation; version 2 of the License.
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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 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 Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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/*
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This program simulates the MariaDB query process execution using
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the SCAN, EQ_REF, REF and join_cache (CACHE) row lookup methods.
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The purpose is to verify that 'prev_record_reads()' function correctly
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estimates the number of lookups we have to do for EQ_REF access
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assuming we have 'one-row-cache' before the lookup.
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The logic for the prev_record_reads() function in this file should
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match the logic in sql_select.cc::prev_record_reads() in MariaDB 11.0
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and above.
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The program generates first a randomized plan with the above
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methods, then executes a full 'query' processing and then lastly
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checks that the number of EQ_REF engine lookups matches the
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estimated number of lookups.
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If the number of estimated lookups are not exact, the plan and
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lookup numbers are printed. That a plan is printed is not to be
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regarded as a failure. It's a failure only of the number of engine
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calls are far greater than the number of estimated lookups.
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Note that the estimated number of lookups are exact only if CACHE
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refills == 1 and if the EQ_REF table only depends on one earlier
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table.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <time.h>
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#define TABLES 21
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#define DEFAULT_TABLES 10
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#define CACHED_ROWS 10000
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#define unlikely(A) A
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enum JOIN_TYPE { SCAN, EQ_REF, REF, CACHE };
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const char *type[]= { "SCAN", "EQ_REF", "REF", "CACHE"};
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typedef unsigned long long DEPEND;
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typedef unsigned int uint;
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typedef unsigned long long ulonglong;
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struct TABLE
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{
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ulonglong data;
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JOIN_TYPE type;
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DEPEND map;
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DEPEND ref_depend_map;
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uint records_in_table;
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uint matching_records;
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uint last_key;
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ulonglong lookups;
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ulonglong *cache; // join cache
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ulong cached_records;
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ulong flushed_caches;
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};
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struct POSITION
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{
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TABLE *table;
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JOIN_TYPE type;
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double records;
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double record_count;
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double records_out;
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double prev_record_read;
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double same_keys;
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ulong refills;
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};
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uint opt_tables= DEFAULT_TABLES;
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bool verbose=0;
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uint rand_init;
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struct TABLE table[TABLES];
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struct POSITION positions[TABLES];
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void do_select(uint table_index);
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static void
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prev_record_reads(POSITION *position, uint idx, DEPEND found_ref,
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double record_count)
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{
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double found= 1.0;
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POSITION *pos_end= position - 1;
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POSITION *cur_pos= position + idx;
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/* Safety against const tables */
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if (!found_ref)
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goto end;
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for (POSITION *pos= cur_pos-1; pos != pos_end; pos--)
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{
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if (found_ref & pos->table->map)
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{
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found_ref&= ~pos->table->map;
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/* Found dependent table */
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if (pos->type == EQ_REF)
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{
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if (!found_ref)
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found*= pos->same_keys;
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}
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else if (pos->type == CACHE)
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{
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if (!found_ref)
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found*= pos->record_count / pos->refills;
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}
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break;
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}
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if (pos->type != CACHE)
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{
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/*
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We are not depending on the current table
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There are 'records_out' rows with identical rows
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value for our depending tables.
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We are ignoring join_cache as in this case the
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preceding tables row combination can change for
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each call.
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*/
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found*= pos->records_out;
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}
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else
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found/= pos->refills;
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}
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end:
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cur_pos->record_count= record_count;
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cur_pos->same_keys= found;
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assert(record_count >= found);
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if (unlikely(found <= 1.0))
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cur_pos->prev_record_read= record_count;
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else if (unlikely(found > record_count))
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cur_pos->prev_record_read=1;
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else
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cur_pos->prev_record_read= record_count / found;
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return;
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}
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void cleanup()
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{
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for (uint i= 0; i < opt_tables ; i++)
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{
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free(table[i].cache);
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table[i].cache= 0;
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}
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}
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void intialize_tables()
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{
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int eq_ref_tables;
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restart:
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eq_ref_tables= 0;
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for (uint i= 0; i < opt_tables ; i++)
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{
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if (i == 0)
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table[i].type= SCAN;
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else
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table[i].type= (JOIN_TYPE) (rand() % 4);
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table[i].records_in_table= rand() % 5+3;
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table[i].matching_records= 2 + rand() % 3;
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table[i].map= (DEPEND) 1 << i;
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table[i].ref_depend_map= 0;
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/* The following is for testing */
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#ifdef FORCE_COMB
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if (i == 5 || i == 6)
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{
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table[i].type= REF;
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table[i].matching_records= 5;
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}
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#endif
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if (table[i].type != SCAN)
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{
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/* This just to make do_select a bit easier */
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table[i].ref_depend_map= ((DEPEND) 1) << (rand() % i);
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if (rand() & 1)
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{
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uint second_depend= rand() % i;
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if (!(table[i].ref_depend_map & second_depend))
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table[i].ref_depend_map|= ((DEPEND) 1) << second_depend;
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}
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}
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if (table[i].type == EQ_REF)
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{
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table[i].matching_records= 1;
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eq_ref_tables++;
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}
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else if (table[i].type != REF)
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table[i].matching_records= table[i].records_in_table;
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table[i].last_key= 0;
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table[i].lookups= 0;
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table[i].cached_records= 0;
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table[i].flushed_caches= 0;
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table[i].cache= 0;
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if (table[i].type == CACHE)
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table[i].cache= (ulonglong*) malloc(CACHED_ROWS *
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sizeof(table[i].data) * i);
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}
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/* We must have at least one EQ_REF table */
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if (!eq_ref_tables)
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{
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cleanup();
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goto restart;
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}
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}
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void optimize_tables()
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{
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double record_count= 1.0, records;
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for (uint i= 0; i < opt_tables ; i++)
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{
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TABLE *tab= table+i;
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positions[i].refills= 0;
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switch (tab->type) {
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case SCAN:
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records= tab->records_in_table;
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break;
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case EQ_REF:
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records= 1.0;
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prev_record_reads(positions, i, tab->ref_depend_map, record_count);
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break;
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case REF:
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records= tab->matching_records;
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break;
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case CACHE:
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records= tab->records_in_table;
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positions[i].refills= (record_count + CACHED_ROWS-1)/ CACHED_ROWS;
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break;
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default:
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assert(0);
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}
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positions[i].table= table + i;
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positions[i].type= table[i].type;
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positions[i].records= records;
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positions[i].record_count= record_count;
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positions[i].records_out= records;
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record_count*= records;
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}
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}
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void process_join_cache(TABLE *tab, uint table_index)
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{
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if (!tab->cached_records)
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return;
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#ifdef PRINT_CACHE
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putc('>', stdout);
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for (uint k= 0 ; k < table_index ; k++)
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{
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printf("%8lld ", tab->cache[k]);
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}
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putc('\n',stdout);
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putc('<', stdout);
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for (uint k= 0 ; k < table_index ; k++)
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{
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printf("%8lld ", tab->cache[k+(tab->cached_records-1)*table_index]);
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}
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putc('\n',stdout);
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#endif
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for (uint k= 0 ; k < tab->records_in_table; k++)
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{
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table[table_index].data= k+1;
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ulonglong *cache= tab->cache;
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for (uint i= 0 ; i < tab->cached_records ; i++)
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{
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for (uint j= 0 ; j < table_index ; j++)
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table[j].data= *cache++;
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do_select(table_index+1);
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}
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}
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tab->flushed_caches++;
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tab->cached_records= 0;
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}
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/*
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Calculate a key depending on multiple tables
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*/
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ulonglong calc_ref_key(DEPEND depend_map)
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{
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ulonglong value= 1;
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TABLE *t= table;
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do
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{
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if (t->map & depend_map)
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{
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depend_map&= ~t->map;
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value*= t->data;
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}
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t++;
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} while (depend_map);
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return value;
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}
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void do_select(uint table_index)
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{
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if (table_index == opt_tables)
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return;
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TABLE *tab= table + table_index;
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switch (tab->type) {
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case SCAN:
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for (uint i= 1 ; i <= tab->records_in_table ; i++)
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{
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tab->data= i;
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do_select(table_index+1);
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}
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break;
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case REF:
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{
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ulonglong ref_key= calc_ref_key(tab->ref_depend_map);
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for (uint i=1 ; i <= tab->matching_records ; i++)
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{
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tab->data= ref_key * tab->matching_records + i;
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do_select(table_index+1);
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}
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break;
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}
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case EQ_REF:
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{
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ulonglong ref_key= calc_ref_key(tab->ref_depend_map);
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if (ref_key != tab->last_key)
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{
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tab->lookups++;
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#ifdef PRINT_EQ_KEY
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if (table_index == 9)
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printf("ref_key: %lld\n", ref_key);
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#endif
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tab->last_key= ref_key;
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tab->data= ref_key * tab->matching_records;
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}
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else
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{
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assert(tab->lookups != 0);
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}
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do_select(table_index+1);
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break;
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}
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case CACHE:
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{
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ulonglong *cache= tab->cache + tab->cached_records * table_index;
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for (uint i= 0 ; i <= table_index ; i++)
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*cache++ = table[i].data;
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if (++tab->cached_records == CACHED_ROWS)
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process_join_cache(tab, table_index);
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break;
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}
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default:
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break;
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}
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return;
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}
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void do_select_end(uint table_index)
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{
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if (table_index == opt_tables)
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return;
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TABLE *tab= table + table_index;
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switch (tab->type) {
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case CACHE:
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process_join_cache(tab, table_index);
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break;
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default:
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break;
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}
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do_select_end(table_index+1);
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}
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void execute()
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{
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do_select(0);
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do_select_end(0);
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}
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int check_prev_records()
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{
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int errors= 0;
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for (uint i= 0; i < opt_tables ; i++)
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{
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TABLE *tab= table + i;
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if (tab->type == EQ_REF)
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{
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if (positions[i].prev_record_read != (double) tab->lookups)
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{
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fprintf(stdout, "table: %d lookups: %lld prev_record_read: %g\n",
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i, tab->lookups, positions[i].prev_record_read);
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errors++;
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}
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}
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}
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if (errors || verbose)
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{
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fprintf(stdout, "tables: %u\n", opt_tables);
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fprintf(stdout, "rand_init: %u\n", rand_init);
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fprintf(stdout, "cache_size: %u\n", (uint) CACHED_ROWS);
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for (uint i= 0; i < opt_tables ; i++)
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{
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TABLE *tab= table + i;
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fprintf(stdout, "table: %2d (%3lx) type: %-6s comb: %3lg out: %2lg lookups: %lld prev: %lg depend: %llx\n",
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i, (uint) 1 << i, type[tab->type], positions[i].record_count,
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positions[i].records_out, tab->lookups,
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positions[i].prev_record_read, tab->ref_depend_map);
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}
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}
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return errors;
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}
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int main(int argc, char **argv)
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{
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if (argc > 1)
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{
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opt_tables=atoi(argv[1]);
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if (opt_tables <= 3)
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opt_tables= 3;
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if (opt_tables > TABLES)
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opt_tables= TABLES;
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}
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if (argc > 2)
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rand_init= atoi(argv[2]);
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else
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rand_init= (uint) time(0);
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srand(rand_init);
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intialize_tables();
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optimize_tables();
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execute();
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cleanup();
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exit(check_prev_records() > 0);
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}
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