mirror of
https://github.com/MariaDB/server.git
synced 2025-07-29 05:21:33 +03:00
Fixed bug mdev-3891.
If a query referenced some system statistical tables, but not all of them, then executing an ANALYZE command simultaneously with this query could lead to a deadlock. The fix prohibited reading statistics from system statistical tables for such queries. Removed the function unlock_tables_n_open_system_tables_for_write() as not used anymore. Performed some minor refactoring of the code in sql_statistics.cc.
This commit is contained in:
Igor Babaev
@ -202,6 +202,21 @@ dbt3_s001 lineitem i_l_shipdate 1 2.6500
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dbt3_s001 lineitem i_l_suppkey 1 600.5000
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dbt3_s001 lineitem i_l_suppkey_partkey 1 30.0250
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dbt3_s001 lineitem i_l_suppkey_partkey 2 8.5786
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set @save_global_use_stat_tables=@@global.use_stat_tables;
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set global use_stat_tables='preferably';
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set debug_sync='RESET';
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set debug_sync='statistics_update_start SIGNAL parker WAIT_FOR go1 EXECUTE 1';
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set debug_sync='thr_multi_lock_after_thr_lock SIGNAL go2 EXECUTE 2';
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use dbt3_s001;
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analyze table lineitem persistent for all;
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set debug_sync='open_and_process_table WAIT_FOR parker';
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set debug_sync='statistics_read_start SIGNAL go1 WAIT_FOR go2';
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use dbt3_s001;
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select * from mysql.index_stats, lineitem where index_name= 'i_l_shipdate' and l_orderkey=1 and l_partkey=68;
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db_name table_name index_name prefix_arity avg_frequency l_orderkey l_partkey l_suppkey l_linenumber l_quantity l_extendedprice l_discount l_tax l_returnflag l_linestatus l_shipDATE l_commitDATE l_receiptDATE l_shipinstruct l_shipmode l_comment
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dbt3_s001 lineitem i_l_shipdate 1 2.6500 1 68 9 2 36 34850.16 0.09 0.06 N O 1996-04-12 1996-02-28 1996-04-20 TAKE BACK RETURN MAIL slyly bold pinto beans detect s
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set debug_sync='RESET';
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set global use_stat_tables=@save_global_use_stat_tables;
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DROP DATABASE dbt3_s001;
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use test;
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set use_stat_tables=@save_use_stat_tables;
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@ -211,6 +211,21 @@ dbt3_s001 lineitem i_l_shipdate 1 2.6496
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dbt3_s001 lineitem i_l_suppkey 1 600.4000
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dbt3_s001 lineitem i_l_suppkey_partkey 1 30.0200
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dbt3_s001 lineitem i_l_suppkey_partkey 2 8.5771
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set @save_global_use_stat_tables=@@global.use_stat_tables;
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set global use_stat_tables='preferably';
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set debug_sync='RESET';
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set debug_sync='statistics_update_start SIGNAL parker WAIT_FOR go1 EXECUTE 1';
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set debug_sync='thr_multi_lock_after_thr_lock SIGNAL go2 EXECUTE 2';
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use dbt3_s001;
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analyze table lineitem persistent for all;
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set debug_sync='open_and_process_table WAIT_FOR parker';
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set debug_sync='statistics_read_start SIGNAL go1 WAIT_FOR go2';
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use dbt3_s001;
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select * from mysql.index_stats, lineitem where index_name= 'i_l_shipdate' and l_orderkey=1 and l_partkey=68;
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db_name table_name index_name prefix_arity avg_frequency l_orderkey l_partkey l_suppkey l_linenumber l_quantity l_extendedprice l_discount l_tax l_returnflag l_linestatus l_shipDATE l_commitDATE l_receiptDATE l_shipinstruct l_shipmode l_comment
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dbt3_s001 lineitem i_l_shipdate 1 2.6496 1 68 9 2 36 34850.16 0.09 0.06 N O 1996-04-12 1996-02-28 1996-04-20 TAKE BACK RETURN MAIL slyly bold pinto beans detect s
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set debug_sync='RESET';
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set global use_stat_tables=@save_global_use_stat_tables;
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DROP DATABASE dbt3_s001;
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use test;
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set use_stat_tables=@save_use_stat_tables;
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@ -196,6 +196,48 @@ set debug_sync='RESET';
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select * from mysql.index_stats where table_name='lineitem'
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order by index_name, prefix_arity;
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#
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# Bug mdev-3891: deadlock for ANALYZE and SELECT over mysql.index_stats
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#
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set @save_global_use_stat_tables=@@global.use_stat_tables;
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set global use_stat_tables='preferably';
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set debug_sync='RESET';
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connect (con1, localhost, root,,);
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connect (con2, localhost, root,,);
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connection con1;
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set debug_sync='statistics_update_start SIGNAL parker WAIT_FOR go1 EXECUTE 1';
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set debug_sync='thr_multi_lock_after_thr_lock SIGNAL go2 EXECUTE 2';
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use dbt3_s001;
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--send analyze table lineitem persistent for all
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connection con2;
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set debug_sync='open_and_process_table WAIT_FOR parker';
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set debug_sync='statistics_read_start SIGNAL go1 WAIT_FOR go2';
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use dbt3_s001;
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--send select * from mysql.index_stats, lineitem where index_name= 'i_l_shipdate' and l_orderkey=1 and l_partkey=68
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connection con1;
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--disable_result_log
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--disable_warnings
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--reap
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--enable_warnings
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--enable_result_log
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connection con2;
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--disable_warnings
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--reap
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--enable_warnings
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connection default;
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disconnect con1;
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disconnect con2;
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set debug_sync='RESET';
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set global use_stat_tables=@save_global_use_stat_tables;
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DROP DATABASE dbt3_s001;
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use test;
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@ -9604,6 +9604,12 @@ has_write_table_auto_increment_not_first_in_pk(TABLE_LIST *tables)
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must call close_system_tables() to close systems tables opened
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with this call.
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NOTES
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In some situations we use this function to open system tables for
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writing. It happens, for examples, with statistical tables when
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they are updated by an ANALYZE command. In these cases we should
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guarantee that system tables will not be deadlocked.
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RETURN
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FALSE Success
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TRUE Error
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@ -9648,70 +9654,6 @@ open_system_tables_for_read(THD *thd, TABLE_LIST *table_list,
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}
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/*
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Unlock opened tables and open and lock system tables for write.
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SYNOPSIS
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unlock_tables_n_open_system_tables_for_write()
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thd Thread context.
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table_list List of tables to open.
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backup Pointer to Open_tables_state instance where
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information about currently open tables will be
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saved, and from which will be restored when we will
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end work with system tables.
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DESCRIPTION
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The function first unlocks the opened tables, but do not close them.
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Then it opens and locks for write the specified system tables.
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NOTE
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The system tables cannot be locked for write without unlocking
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the current opened tables. Yet in some cases we still need valid TABLE
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structures for these tables to be able to extract data that is to be
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written into the system tables.
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This function is used when updating the statistical tables.
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RETURN
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FALSE Success
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TRUE Error
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*/
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bool
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unlock_tables_n_open_system_tables_for_write(THD *thd,
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TABLE_LIST *table_list,
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Open_tables_backup *backup)
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{
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Query_tables_list query_tables_list_backup;
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LEX *lex= thd->lex;
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DBUG_ENTER("unlock_tables_n_open_system_tables_for_write");
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lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
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thd->reset_n_backup_open_tables_state(backup);
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if (open_and_lock_tables(thd, table_list, FALSE,
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MYSQL_OPEN_IGNORE_FLUSH | MYSQL_LOCK_IGNORE_TIMEOUT))
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{
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lex->restore_backup_query_tables_list(&query_tables_list_backup);
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goto error;
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}
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for (TABLE_LIST *tables= table_list; tables; tables= tables->next_global)
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{
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DBUG_ASSERT(tables->table->s->table_category == TABLE_CATEGORY_SYSTEM);
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tables->table->use_all_columns();
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}
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lex->restore_backup_query_tables_list(&query_tables_list_backup);
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DBUG_RETURN(FALSE);
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error:
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close_system_tables(thd, backup);
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DBUG_RETURN(TRUE);
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}
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/*
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Close system tables, opened with open_system_tables_for_read().
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@ -275,9 +275,6 @@ bool is_equal(const LEX_STRING *a, const LEX_STRING *b);
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/* Functions to work with system tables. */
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bool open_system_tables_for_read(THD *thd, TABLE_LIST *table_list,
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Open_tables_backup *backup);
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bool unlock_tables_n_open_system_tables_for_write(THD *thd,
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TABLE_LIST *table_list,
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Open_tables_backup *backup);
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void close_system_tables(THD *thd, Open_tables_backup *backup);
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void close_mysql_tables(THD *thd);
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TABLE *open_system_table_for_update(THD *thd, TABLE_LIST *one_table);
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@ -126,6 +126,38 @@ inline void init_table_list_for_single_stat_table(TABLE_LIST *tbl,
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}
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/**
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@brief
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Open all statistical tables and lock them
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*/
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static
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inline int open_stat_tables(THD *thd, TABLE_LIST *tables,
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Open_tables_backup *backup,
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bool for_write)
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{
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init_table_list_for_stat_tables(tables, for_write);
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init_mdl_requests(tables);
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return open_system_tables_for_read(thd, tables, backup);
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}
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/**
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@brief
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Open a statistical table and lock it
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*/
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static
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inline int open_single_stat_table(THD *thd, TABLE_LIST *table,
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const LEX_STRING *stat_tab_name,
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Open_tables_backup *backup,
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bool for_write)
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{
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init_table_list_for_single_stat_table(table, stat_tab_name, for_write);
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init_mdl_requests(table);
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return open_system_tables_for_read(thd, table, backup);
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}
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/**
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@details
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If the value of the parameter is_safe is TRUE then the function
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@ -1199,7 +1231,7 @@ public:
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the number of distinct values for a column. The class employs the
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Unique class for this purpose.
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The class Count_distinct_field is used only by the function
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collect_statistics_from_table to calculate the values for
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collect_statistics_for_table to calculate the values for
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column avg_frequency of the statistical table column_stats.
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*/
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@ -2179,12 +2211,9 @@ int update_statistics_for_table(THD *thd, TABLE *table)
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DBUG_ENTER("update_statistics_for_table");
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init_table_list_for_stat_tables(tables, TRUE);
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init_mdl_requests(tables);
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DEBUG_SYNC(thd, "statistics_update_start");
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if (unlock_tables_n_open_system_tables_for_write(thd,
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tables,
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&open_tables_backup))
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if (open_stat_tables(thd, tables, &open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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@ -2266,7 +2295,7 @@ int update_statistics_for_table(THD *thd, TABLE *table)
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The parameter stat_tables should point to an array of TABLE_LIST
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objects for all statistical tables linked into a list. All statistical
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tables are supposed to be opened.
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The function is called by read_statistics_for_table_if_needed().
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The function is called by read_statistics_for_tables_if_needed().
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@retval
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0 If data has been successfully read for the table
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@ -2415,6 +2444,21 @@ bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
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return FALSE;
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}
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/*
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Do not read statistics for any query over non-user tables.
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If the query references some statistical tables, but not all
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of them, reading the statistics may lead to a deadlock
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*/
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for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
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{
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if (!tl->is_view_or_derived() && tl->table)
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{
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TABLE_SHARE *table_share= tl->table->s;
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if (table_share && table_share->table_category != TABLE_CATEGORY_USER)
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return FALSE;
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}
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}
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for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
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{
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if (!tl->is_view_or_derived() && tl->table)
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@ -2460,12 +2504,12 @@ int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables)
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DBUG_ENTER("read_statistics_for_table_if_needed");
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DEBUG_SYNC(thd, "statistics_read_start");
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if (!statistics_for_tables_is_needed(thd, tables))
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DBUG_RETURN(0);
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init_table_list_for_stat_tables(stat_tables, FALSE);
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init_mdl_requests(stat_tables);
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if (open_system_tables_for_read(thd, stat_tables, &open_tables_backup))
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if (open_stat_tables(thd, stat_tables, &open_tables_backup, FALSE))
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{
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thd->clear_error();
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DBUG_RETURN(1);
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@ -2527,12 +2571,7 @@ int delete_statistics_for_table(THD *thd, LEX_STRING *db, LEX_STRING *tab)
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DBUG_ENTER("delete_statistics_for_table");
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init_table_list_for_stat_tables(tables, TRUE);
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init_mdl_requests(tables);
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if (open_system_tables_for_read(thd,
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tables,
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&open_tables_backup))
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if (open_stat_tables(thd, tables, &open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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@ -2619,12 +2658,8 @@ int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col)
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DBUG_ENTER("delete_statistics_for_column");
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init_table_list_for_single_stat_table(&tables, &stat_table_name[1], TRUE);
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init_mdl_requests(&tables);
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if (open_system_tables_for_read(thd,
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&tables,
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&open_tables_backup))
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if (open_single_stat_table(thd, &tables, &stat_table_name[1],
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&open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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@ -2692,12 +2727,8 @@ int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
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DBUG_ENTER("delete_statistics_for_index");
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init_table_list_for_single_stat_table(&tables, &stat_table_name[2], TRUE);
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init_mdl_requests(&tables);
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if (open_system_tables_for_read(thd,
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&tables,
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&open_tables_backup))
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if (open_single_stat_table(thd, &tables, &stat_table_name[2],
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&open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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@ -2779,12 +2810,7 @@ int rename_table_in_stat_tables(THD *thd, LEX_STRING *db, LEX_STRING *tab,
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DBUG_ENTER("rename_table_in_stat_tables");
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init_table_list_for_stat_tables(tables, TRUE);
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init_mdl_requests(tables);
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if (open_system_tables_for_read(thd,
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tables,
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&open_tables_backup))
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if (open_stat_tables(thd, tables, &open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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@ -2876,12 +2902,8 @@ int rename_column_in_stat_tables(THD *thd, TABLE *tab, Field *col,
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DBUG_ENTER("rename_column_in_stat_tables");
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init_table_list_for_single_stat_table(&tables, &stat_table_name[1], TRUE);
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init_mdl_requests(&tables);
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if (open_system_tables_for_read(thd,
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&tables,
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&open_tables_backup))
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if (open_single_stat_table(thd, &tables, &stat_table_name[1],
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&open_tables_backup, TRUE))
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{
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thd->clear_error();
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DBUG_RETURN(rc);
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Reference in New Issue
Block a user