Basically, we have a big production issue where our sql queries takes more than 300 seconds before ending.
We are using Mysql as SQL server, and our tables are with MyISAM.
The problematic queries are basic queries between two tables, and with a sort and group by. The issue is that each table has more than 30 millions rows.
Here is a fake example of this query :
SELECT
i.id_stat as idStat,
SUM(srv0.duree_st) AS dureeAppelTotale,
_date as dateI,
DATE_FORMAT(srv0._date,'%d/%m') AS datekey,
DATE_FORMAT(_date,'%d%m%Y') AS datekeyGroup,
heure,
SUM(srv0.nombre_st) AS nbAppel
FROM ids_stat i , SRV201606 srv0
WHERE i.id_rubrique = srv0.id_rubrique
AND i.id_appli = 24071
AND srv0._date >= '2016-06-01 00:00:00'
AND srv0._date <= '2016-07-01 00:00:00'
GROUP BY id_stat, datekeyGroup, heure
ORDER BY _date
Indexes on the ids_stat table are :
show index from ids_stat;
+----------+------------+---------------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+----------+------------+---------------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+
| ids_stat | 0 | PRIMARY | 1 | id_rubrique | A | 7435537 | NULL | NULL | | BTREE | |
| ids_stat | 1 | id_appli_index | 1 | id_appli | A | 13593 | NULL | NULL | | BTREE | |
| ids_stat | 1 | date_creation_index | 1 | date_creation | A | 2478512 | NULL | NULL | | BTREE | |
on the SRV0 table, indexes are :
show index from SRV201606;
+-----------+------------+----------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+-----------+------------+----------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+
| SRV201606 | 0 | PRIMARY | 1 | _date | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 0 | PRIMARY | 2 | heure | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 0 | PRIMARY | 3 | minute | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 0 | PRIMARY | 4 | id_plaque | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 0 | PRIMARY | 5 | id_rubrique | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 0 | PRIMARY | 6 | id_combinaison | A | 27472765 | NULL | NULL | | BTREE | |
| SRV201606 | 1 | id_rubrique | 1 | id_rubrique | A | NULL | NULL | NULL | | BTREE | |
| SRV201606 | 1 | id_combinaison | 1 | id_combinaison | A | NULL | NULL | NULL | | BTREE | |
Also, here is an explain of the query :
+----+-------------+-------+------+------------------------+----------------+---------+-----------------------------+------+---------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+------+------------------------+----------------+---------+-----------------------------+------+---------------------------------+
| 1 | SIMPLE | i | ref | PRIMARY,id_appli_index | id_appli_index | 2 | const | 153 | Using temporary; Using filesort |
| 1 | SIMPLE | srv0 | ref | PRIMARY,id_rubrique | id_rubrique | 8 | StatVoxProdV2.i.id_rubrique | 16 | Using where |
We also read that these old join made with where were harmless as they are transcripted as an inner join by the sql engine.
Can you help us fiding ways to tune our mysql Server so it can be boosted ? Is there any configuration that could help us out ?
Many thanks
[EDIT]
As asked in the comments, here is he version :
SELECT VERSION();
+------------+
| VERSION() |
+------------+
| 5.0.45-log |
Server variables :
show Variables;
+---------------------------------+----------------------------------+
| Variable_name | Value |
+---------------------------------+----------------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr/local/ |
| binlog_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/local/share/mysql/charsets/ |
| collation_connection | utf8_general_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
| completion_type | 0 |
| concurrent_insert | 1 |
| connect_timeout | 5 |
| datadir | THEDATADIR |
| date_format | %Y-%m-%d |
| datetime_format | %Y-%m-%d %H:%i:%s |
| default_week_format | 0 |
| delay_key_write | ON |
| delayed_insert_limit | 100 |
| delayed_insert_timeout | 300 |
| delayed_queue_size | 1000 |
| div_precision_increment | 4 |
| engine_condition_pushdown | OFF |
| expire_logs_days | 32 |
| flush | OFF |
| flush_time | 0 |
| ft_boolean_syntax | + -><()~*:""&| |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| group_concat_max_len | 1024 |
| have_archive | NO |
| have_bdb | NO |
| have_blackhole_engine | NO |
| have_compress | YES |
| have_crypt | YES |
| have_csv | NO |
| have_dynamic_loading | YES |
| have_example_engine | NO |
| have_federated_engine | NO |
| have_geometry | YES |
| have_innodb | DISABLED |
| have_isam | NO |
| have_merge_engine | YES |
| have_ndbcluster | NO |
| have_openssl | NO |
| have_ssl | NO |
| have_query_cache | YES |
| have_raid | NO |
| have_rtree_keys | YES |
| have_symlink | YES |
| hostname | THEHOSTNAME |
| init_connect | |
| init_file | |
| init_slave | |
| innodb_additional_mem_pool_size | 1048576 |
| innodb_autoextend_increment | 8 |
| innodb_buffer_pool_awe_mem_mb | 0 |
| innodb_buffer_pool_size | 1048576 |
| innodb_checksums | ON |
| innodb_commit_concurrency | 0 |
| innodb_concurrency_tickets | 500 |
| innodb_data_file_path | |
| innodb_data_home_dir | |
| innodb_doublewrite | ON |
| innodb_fast_shutdown | 1 |
| innodb_file_io_threads | 4 |
| innodb_file_per_table | OFF |
| innodb_flush_log_at_trx_commit | 1 |
| innodb_flush_method | |
| innodb_force_recovery | 0 |
| innodb_lock_wait_timeout | 50 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_arch_dir | |
| innodb_log_archive | OFF |
| innodb_log_buffer_size | 1048576 |
| innodb_log_file_size | 5242880 |
| innodb_log_files_in_group | 2 |
| innodb_log_group_home_dir | |
| innodb_max_dirty_pages_pct | 90 |
| innodb_max_purge_lag | 0 |
| innodb_mirrored_log_groups | 1 |
| innodb_open_files | 300 |
| innodb_rollback_on_timeout | OFF |
| innodb_support_xa | ON |
| innodb_sync_spin_loops | 20 |
| innodb_table_locks | ON |
| innodb_thread_concurrency | 8 |
| innodb_thread_sleep_delay | 10000 |
| interactive_timeout | 28800 |
| join_buffer_size | 131072 |
| key_buffer_size | 402653184 |
| key_cache_age_threshold | 300 |
| key_cache_block_size | 1024 |
| key_cache_division_limit | 100 |
| language | /usr/local/share/mysql/english/ |
| large_files_support | ON |
| large_page_size | 0 |
| large_pages | OFF |
| lc_time_names | en_US |
| license | GPL |
| local_infile | ON |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | ON |
| log_bin_trust_function_creators | OFF |
| log_error | |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_queries | ON |
| log_warnings | 1 |
| long_query_time | 10 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 1047552 |
| max_binlog_cache_size | 4294967295 |
| max_binlog_size | 104857600 |
| max_connect_errors | 10 |
| max_connections | 100 |
| max_delayed_threads | 20 |
| max_error_count | 64 |
| max_heap_table_size | 134217728 |
| max_insert_delayed_threads | 20 |
| max_join_size | 4294967295 |
| max_length_for_sort_data | 1024 |
| max_prepared_stmt_count | 16382 |
| max_relay_log_size | 0 |
| max_seeks_for_key | 4294967295 |
| max_sort_length | 1024 |
| max_sp_recursion_depth | 0 |
| max_tmp_tables | 32 |
| max_user_connections | 0 |
| max_write_lock_count | 4294967295 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 2147483647 |
| myisam_recover_options | OFF |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 67108864 |
| myisam_stats_method | nulls_unequal |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old_passwords | OFF |
| open_files_limit | 4096 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| pid_file | /usr2/mysql/var/run/mysqld.pid |
| port | 3306 |
| preload_buffer_size | 32768 |
| profiling | OFF |
| profiling_history_size | 15 |
| protocol_version | 10 |
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 33554432 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| range_alloc_block_size | 2048 |
| read_buffer_size | 2093056 |
| read_only | OFF |
| read_rnd_buffer_size | 8384512 |
| relay_log_purge | ON |
| relay_log_space_limit | 0 |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| secure_file_priv | |
| server_id | 2 |
| skip_external_locking | ON |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_load_tmpdir | /usr2/mysql/tmp/ |
| slave_net_timeout | 3600 |
| slave_skip_errors | ALL |
| slave_transaction_retries | 10 |
| slow_launch_time | 2 |
| socket | /usr2/mysql/var/run/mysqld.sock |
| sort_buffer_size | 2097144 |
| sql_big_selects | ON |
| sql_mode | |
| sql_notes | ON |
| sql_warnings | OFF |
| ssl_ca | |
| ssl_capath | |
| ssl_cert | |
| ssl_cipher | |
| ssl_key | |
| storage_engine | MyISAM |
| sync_binlog | 0 |
| sync_frm | ON |
| system_time_zone | CET |
| table_cache | 512 |
| table_lock_wait_timeout | 50 |
| table_type | MyISAM |
| thread_cache_size | 8 |
| thread_stack | 196608 |
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| tmp_table_size | 134217728 |
| tmpdir | /usr2/mysql/tmp/ |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| updatable_views_with_limit | YES |
| version | 5.0.45-log |
| version_comment | Source distribution |
| version_compile_machine | i686 |
| version_compile_os | pc-linux-gnu |
| wait_timeout | 28800 |
ids_stat schema :
SHOW CREATE TABLE ids_stat;
CREATE TABLE `ids_stat` (
`id_rubrique` bigint(20) NOT NULL default '0',
`id_stat` int(10) default NULL,
`id_appli` smallint(5) unsigned NOT NULL default '0',
`nom_rubrique` varchar(240) NOT NULL,
`date_creation` timestamp NOT NULL default CURRENT_TIMESTAMP,
PRIMARY KEY (`id_rubrique`),
KEY `id_appli_index` (`id_appli`),
KEY `date_creation_index` (`date_creation`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
And the SRV0 example schema :
CREATE TABLE `SRV201606` (
`id_rubrique` bigint(20) NOT NULL default '0',
`id_plaque` tinyint(3) unsigned NOT NULL default '0',
`id_combinaison` smallint(5) unsigned NOT NULL default '0',
`_date` date NOT NULL default '0000-00-00',
`heure` tinyint(3) NOT NULL default '0',
`minute` tinyint(3) NOT NULL default '0',
`nombre_entree` mediumint(8) unsigned default '0',
`nombre_st` mediumint(8) unsigned default NULL,
`duree_st` mediumint(8) unsigned default NULL,
`flag` tinyint(3) unsigned NOT NULL default '0',
PRIMARY KEY (`_date`,`heure`,`minute`,`id_plaque`,`id_rubrique`,`id_combinaison`),
KEY `id_rubrique` (`id_rubrique`),
KEY `id_combinaison` (`id_combinaison`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
This is not my finished Answer!,
but can you only run this query on your big tables and give me the execution time and the EXPLAIN of it.
ALTER TABLE SRV201606 ADD KEY idx_rubrique_date (_date,id_rubrique);
SELECT
i.*,
SUM(srv0.duree_st) AS dureeAppelTotale,
srv0._date AS dateI,
DATE_FORMAT(srv0._date,'%d/%m') AS datekey,
DATE_FORMAT(_date,'%d%m%Y') AS datekeyGroup,
heure,
SUM(srv0.nombre_st) AS nbAppel
FROM (
SELECT
id_rubrique
, id_stat
FROM ids_stat
WHERE
id_appli = 24071
GROUP BY id_stat
) AS i
LEFT JOIN SRV201606 srv0 ON i.id_rubrique = srv0.id_rubrique
WHERE
srv0._date >= '2016-06-01'
AND
srv0._date <= '2016-07-01'
GROUP BY id_stat, _date, heure
ORDER BY _date;
You could try adding _date to
CREATE TABLE `SRV201606` (
...
KEY `id_rubrique` (`id_rubrique`),
so
KEY `id_rubrique` (`_date`,`id_rubrique`),
or alternatively
KEY `date-id_rubrique` (`_date`,`id_rubrique`),
Can you try removing the times from the dates and post the EXPLAIN, something like this:-
SELECT
i.id_stat as idStat,
SUM(srv0.duree_st) AS dureeAppelTotale,
_date as dateI,
DATE_FORMAT(srv0._date,'%d/%m') AS datekey,
DATE_FORMAT(_date,'%d%m%Y') AS datekeyGroup,
heure,
SUM(srv0.nombre_st) AS nbAppel
FROM ids_stat i
INNER JOIN SRV201606 srv0
ON i.id_rubrique = srv0.id_rubrique
WHERE i.id_appli = 24071
AND srv0._date BETWEEN '2016-06-01' AND '2016-07-01'
GROUP BY id_stat,
datekeyGroup,
heure
ORDER BY _date
I suspect that MySQL is trying to do a date conversion to a date / time for each row returned.
WHERE i.id_rubrique = srv0.id_rubrique
AND i.id_appli = 24071
AND srv0._date >= '2016-06-01 00:00:00'
AND srv0._date <= '2016-07-01 00:00:00'
Did you want both midnights? Suggest doing this instead:
AND srv0._date >= '2016-06-01'
AND srv0._date < '2016-06-01' + INTERVAL 1 MONTH
Need these indexes to facilitate starting with i:
i: (id_appli, id_rubrique, id_stat) -- in this order; and is 'covering'
srv0: (id_rubrique, _date) -- '=' part first, then 'range'
Need these indexes to facilitate starting with srv0:
i: (id_rubrique, id_appli, id_stat) -- in this order; and is 'covering'
srv0: (_date) -- adding anything after `_date` is useless
Adding all those indexes will give the optimizer the option to start with either table and do it efficiently.
MySql is consuming more than 80% of the memory. I am not a mysql expert, please let me know any configuration has wrong value.
mysql> SHOW VARIABLES;
These are my configurations
| Variable_name | Value |
+---------------------------------------------------+---------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| autocommit | ON |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr |
| big_tables | OFF |
| binlog_cache_size | 32768 |
| binlog_direct_non_transactional_updates | OFF |
| binlog_format | STATEMENT |
| binlog_stmt_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/|
| collation_connection | utf8_general_ci |
| collation_database | utf8_general_ci |
| collation_server | utf8_general_ci |
| completion_type | NO_CHAIN |
| concurrent_insert | AUTO |
| connect_timeout | 10 |
| datadir | /var/lib/mysql/ |
| date_format | %Y-%m-%d |
| datetime_format | %Y-%m-%d %H:%i:%s |
| default_storage_engine | InnoDB |
| default_week_format | 0 |
| delay_key_write | ON |
| delayed_insert_limit | 100 |
| delayed_insert_timeout | 300 |
| delayed_queue_size | 1000 |
| div_precision_increment | 4 |
| engine_condition_pushdown | ON |
| error_count | 0 |
| event_scheduler | OFF |
| expire_logs_days | 3 |
| external_user | |
| flush | OFF |
| flush_time | 0 |
| foreign_key_checks | ON |
| ft_boolean_syntax | + -><()~*:""&| |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| general_log | OFF |
| general_log_file | /var/lib/mysql/db.log |
| group_concat_max_len | 1024 |
| have_compress | YES |
| have_crypt | YES |
| have_csv | YES |
| have_dynamic_loading | YES |
| have_geometry | YES |
| have_innodb | YES |
| have_ndbcluster | NO |
| have_openssl | DISABLED |
| have_partitioning | YES |
| have_profiling | YES |
| have_query_cache | YES |
| have_rtree_keys | YES |
| have_ssl | DISABLED |
| have_symlink | DISABLED |
| hostname | xxx.xxx.xxxxxx |
| identity | 0 |
| ignore_builtin_innodb | OFF |
| init_connect | |
| init_file | |
| init_slave | |
| innodb_adaptive_flushing | ON |
| innodb_adaptive_hash_index | ON |
| innodb_additional_mem_pool_size | 20971520 |
| innodb_autoextend_increment | 8 |
| innodb_autoinc_lock_mode | 1 |
| innodb_buffer_pool_instances | 1 |
| innodb_buffer_pool_size | 11811160064 |
| innodb_change_buffering | all |
| innodb_checksums | ON |
| innodb_commit_concurrency | 0 |
| innodb_concurrency_tickets | 500 |
| innodb_data_file_path | ibdata1:10M:autoextend |
| innodb_data_home_dir | |
| innodb_doublewrite | ON |
| innodb_fast_shutdown | 1 |
| innodb_file_format | Antelope |
| innodb_file_format_check | ON |
| innodb_file_format_max | Antelope |
| innodb_file_per_table | ON |
| innodb_flush_log_at_trx_commit | 2 |
| innodb_flush_method | O_DIRECT |
| innodb_force_load_corrupted | OFF |
| innodb_force_recovery | 0 |
| innodb_io_capacity | 20000 |
| innodb_large_prefix | OFF |
| innodb_lock_wait_timeout | 50 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_buffer_size | 8388608 |
| innodb_log_file_size | 2146435072 |
| innodb_log_files_in_group | 2 |
| innodb_log_group_home_dir | ./ |
| innodb_max_dirty_pages_pct | 75 |
| innodb_max_purge_lag | 0 |
| innodb_mirrored_log_groups | 1 |
| innodb_old_blocks_pct | 37 |
| innodb_old_blocks_time | 0 |
| innodb_open_files | 300 |
| innodb_print_all_deadlocks | OFF |
| innodb_purge_batch_size | 20 |
| innodb_purge_threads | 0 |
| innodb_random_read_ahead | OFF |
| innodb_read_ahead_threshold | 56 |
| innodb_read_io_threads | 64 |
| innodb_replication_delay | 0 |
| innodb_rollback_on_timeout | OFF |
| innodb_rollback_segments | 128 |
| innodb_spin_wait_delay | 6 |
| innodb_stats_method | nulls_equal |
| innodb_stats_on_metadata | ON |
| innodb_stats_sample_pages | 8 |
| innodb_strict_mode | OFF |
| innodb_support_xa | ON |
| innodb_sync_spin_loops | 30 |
| innodb_table_locks | ON |
| innodb_thread_concurrency | 0 |
| innodb_thread_sleep_delay | 10000 |
| innodb_use_native_aio | ON |
| innodb_use_sys_malloc | ON |
| innodb_version | 5.5.30 |
| innodb_write_io_threads | 64 |
| insert_id | 0 |
| interactive_timeout | 28800 |
| join_buffer_size | 131072 |
| keep_files_on_create | OFF |
| key_buffer_size | 1073741824 |
| key_cache_age_threshold | 300 |
| key_cache_block_size | 1024 |
| key_cache_division_limit | 100 |
| large_files_support | ON |
| large_page_size | 0 |
| large_pages | OFF |
| last_insert_id | 0 |
| lc_messages | en_US |
| lc_messages_dir | /usr/share/mysql/ |
| lc_time_names | en_US |
| license | GPL |
| local_infile | ON |
| lock_wait_timeout | 31536000 |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | ON |
| log_bin_trust_function_creators | OFF |
| log_error | /var/log/mysqld.log |
| log_output | FILE |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_queries | ON |
| log_warnings | 1 |
| long_query_time | 1.000000 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 67108864 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| max_binlog_stmt_cache_size | 18446744073709547520 |
| max_connect_errors | 10000 |
| max_connections | 300 |
| max_delayed_threads | 20 |
| max_error_count | 64 |
| max_heap_table_size | 16777216 |
| max_insert_delayed_threads | 20 |
| max_join_size | 18446744073709551615 |
| max_length_for_sort_data | 1024 |
| max_long_data_size | 67108864 |
| max_prepared_stmt_count | 16382 |
| max_relay_log_size | 0 |
| max_seeks_for_key | 18446744073709551615 |
| max_sort_length | 1024 |
| max_sp_recursion_depth | 0 |
| max_tmp_tables | 32 |
| max_user_connections | 0 |
| max_write_lock_count | 18446744073709551615 |
| metadata_locks_cache_size | 1024 |
| min_examined_row_limit | 0 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 9223372036853727232 |
| myisam_mmap_size | 18446744073709551615 |
| myisam_recover_options | OFF |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 8388608 |
| myisam_stats_method | nulls_unequal |
| myisam_use_mmap | OFF |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old | OFF |
| old_alter_table | OFF |
| old_passwords | OFF |
| open_files_limit | 1810 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| performance_schema | OFF |
| performance_schema_events_waits_history_long_size | 10000 |
| performance_schema_events_waits_history_size | 10 |
| performance_schema_max_cond_classes | 80 |
| performance_schema_max_cond_instances | 1000 |
| performance_schema_max_file_classes | 50 |
| performance_schema_max_file_handles | 32768 |
| performance_schema_max_file_instances | 10000 |
| performance_schema_max_mutex_classes | 200 |
| performance_schema_max_mutex_instances | 1000000 |
| performance_schema_max_rwlock_classes | 30 |
| performance_schema_max_rwlock_instances | 1000000 |
| performance_schema_max_table_handles | 100000 |
| performance_schema_max_table_instances | 50000 |
| performance_schema_max_thread_classes | 50 |
| performance_schema_max_thread_instances | 1000 |
| pid_file | /var/run/mysqld/mysqld.pid|
| plugin_dir | /usr/lib64/mysql/plugin/ |
| port | 3306 |
| preload_buffer_size | 32768 |
| profiling | OFF |
| profiling_history_size | 15 |
| protocol_version | 10 |
| proxy_user | |
| pseudo_slave_mode | OFF |
| pseudo_thread_id | 49031 |
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 67108864 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| rand_seed1 | 0 |
| rand_seed2 | 0 |
| range_alloc_block_size | 4096 |
| read_buffer_size | 1048576 |
| read_only | OFF |
| read_rnd_buffer_size | 262144 |
| relay_log | |
| relay_log_index | |
| relay_log_info_file | relay-log.info |
| relay_log_purge | ON |
| relay_log_recovery | OFF |
| relay_log_space_limit | 0 |
| report_host | |
| report_password | |
| report_port | 3306 |
| report_user | |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| secure_file_priv | |
| server_id | 21 |
| skip_external_locking | ON |
| skip_name_resolve | OFF |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_exec_mode | STRICT |
| slave_load_tmpdir | /tmp |
| slave_max_allowed_packet | 1073741824 |
| slave_net_timeout | 3600 |
| slave_skip_errors | OFF |
| slave_transaction_retries | 10 |
| slave_type_conversions | |
| slow_launch_time | 2 |
| slow_query_log | ON |
| slow_query_log_file | /server/logs/log-slow-queries.log |
| socket | /var/lib/mysql/mysql.sock |
| sort_buffer_size | 1048576 |
| sql_auto_is_null | OFF |
| sql_big_selects | ON |
| sql_big_tables | OFF |
| sql_buffer_result | OFF |
| sql_log_bin | ON |
| sql_log_off | OFF |
| sql_low_priority_updates | OFF |
| sql_max_join_size | 18446744073709551615 |
| sql_mode | |
| sql_notes | ON |
| sql_quote_show_create | ON |
| sql_safe_updates | OFF |
| sql_select_limit | 18446744073709551615 |
| sql_slave_skip_counter | 0 |
| sql_warnings | OFF |
| ssl_ca | |
| ssl_capath | |
| ssl_cert | |
| ssl_cipher | |
| ssl_key | |
| storage_engine | InnoDB |
| stored_program_cache | 256 |
| sync_binlog | 0 |
| sync_frm | ON |
| sync_master_info | 0 |
| sync_relay_log | 0 |
| sync_relay_log_info | 0 |
| system_time_zone | HKT |
| table_definition_cache | 400 |
| table_open_cache | 800 |
| thread_cache_size | 100 |
| thread_concurrency | 10 |
| thread_handling | one-thread-per-connection |
| thread_stack | 262144 |
| time_format | %H:%i:%s |
| time_zone | Asia/Hong_Kong |
| timed_mutexes | OFF |
| timestamp | 1441179155 |
| tmp_table_size | 16777216 |
| tmpdir | /tmp |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| unique_checks | ON |
| updatable_views_with_limit | YES |
| version | 5.5.30-log | |
| version_compile_machine | x86_64 |
| version_compile_os | Linux |
| wait_timeout | 28800 |
| warning_count | 0
I have a very simple query
select count(*) from user_access where user_name='mike'
on a table
+-----------+-------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+-------------------+-----------------------------+
| user_name | varchar(32) | NO | PRI | NULL | |
| sample_id | int(11) | NO | PRI | 0 | |
| updated | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-----------+-------------+------+-----+-------------------+-----------------------------+
I have tried this over the network and on the host itself and either way it hangs
| 14051 | | localhost | nir | Query | 677 | Sending data | select count(*) from user_access where user_name='mike'
Here is a list of the buffers & caches & such
+---------------------------------------------------+----------------------+
| Variable_name | Value |
+---------------------------------------------------+----------------------+
| binlog_cache_size | 32768 |
| binlog_stmt_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| delayed_queue_size | 1000 |
| innodb_additional_mem_pool_size | 8388608 |
| innodb_buffer_pool_size | 134217728 |
| innodb_log_buffer_size | 8388608 |
| innodb_log_file_size | 5242880 |
| innodb_purge_batch_size | 20 |
| join_buffer_size | 131072 |
| key_buffer_size | 16777216 |
| key_cache_block_size | 1024 |
| large_page_size | 0 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 104857600 |
| max_binlog_stmt_cache_size | 18446744073709547520 |
| max_heap_table_size | 16777216 |
| max_join_size | 18446744073709551615 |
| max_long_data_size | 67108864 |
| max_relay_log_size | 0 |
| metadata_locks_cache_size | 1024 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 9223372036853727232 |
| myisam_mmap_size | 18446744073709551615 |
| myisam_sort_buffer_size | 8388608 |
| performance_schema_events_waits_history_long_size | 10000 |
| performance_schema_events_waits_history_size | 10 |
| preload_buffer_size | 32768 |
| profiling_history_size | 15 |
| query_alloc_block_size | 8192 |
| query_cache_size | 16777216 |
| query_prealloc_size | 8192 |
| range_alloc_block_size | 4096 |
| read_buffer_size | 131072 |
| read_rnd_buffer_size | 262144 |
| sort_buffer_size | 2097152 |
| sql_max_join_size | 18446744073709551615 |
| thread_cache_size | 8 |
| tmp_table_size | 16777216 |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
+---------------------------------------------------+----------------------+
If there is other data that someone would like to see, I'll get it.
There is a pretty vanilla query. Can anyone suggest a place to look for the problem?
The output of EXPLAIN is
+----+-------------+-------------+-------+---------------+---------+---------+------+-------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------+-------+---------------+---------+---------+------+-------+--------------------------+
| 1 | SIMPLE | user_access | index | NULL | PRIMARY | 38 | NULL | 57224 | Using where; Using index |
I have a Web server running on RHEL that is running Apache and MySQL. It has a Quad core 3.2Ghz Xeon CPU and 8 Gigs of RAM Most of the time, we don't have any issues at all.
Our web application is very database intensive. When our usage gets pretty heavy MySQL will peg out at using 24.9% of the cpu. Most of the time, it hangs around below 5%. I have speculated that it is only using one core of the CPU and it is pegging out that core but TOP shows me in the cpu column that mysqld changes cores even while the usage stays at 24.9%. When it does this MySQL gets painfully slow as it is queuing up queries Is there some magic configuration that will tell mysql to use more cpu when it needs to? Also, any other advice on my configuration would be helpful.
We run two applications on this server. One that runs Innodb but doesn't get much usage (it has been replaced by the other app), and one that runs MyIsam and gets lots of use. Overall, our whole mysql data directory is something like 13Gigs if that matters at all.
Here is my config:
[root#ProductionLinux root]# cat /etc/my.cnf
[mysqld]
server-id = 71
log-bin = /var/log/mysql/mysql-bin.log
binlog-do-db = oldapplication
binlog-do-db = newapplication
binlog-do-db = support
thread_cache_size = 30
key_buffer_size = 256M
table_cache = 256
sort_buffer_size = 4M
read_buffer_size = 1M
skip-name-resolve
innodb_data_home_dir = /usr/local/mysql/data/
innodb_data_file_path = InnoDB:100M:autoextend
set-variable = innodb_buffer_pool_size=70M
set-variable = innodb_additional_mem_pool_size=10M
set-variable = max_connections=500
innodb_log_group_home_dir = /usr/local/mysql/data
innodb_log_arch_dir = /usr/local/mysql/data
set-variable = innodb_log_file_size=20M
set-variable = innodb_log_buffer_size=8M
innodb_flush_log_at_trx_commit = 1
log-queries-not-using-indexes
log-error = /var/log/mysql/mysql-error.log
Any help here?
mysql> show variables;
+---------------------------------+-----------------------------------------------------------------------------+
| Variable_name | Value |
+---------------------------------+-----------------------------------------------------------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr/local/mysql-standard-5.0.18-linux-x86_64-glibc23/ |
| binlog_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/local/mysql-standard-5.0.18-linux-x86_64-glibc23/share/mysql/charsets/ |
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
| completion_type | 0 |
| concurrent_insert | 1 |
| connect_timeout | 5 |
| datadir | /usr/local/mysql/data/ |
| date_format | %Y-%m-%d |
| datetime_format | %Y-%m-%d %H:%i:%s |
| default_week_format | 0 |
| delay_key_write | ON |
| delayed_insert_limit | 100 |
| delayed_insert_timeout | 300 |
| delayed_queue_size | 1000 |
| div_precision_increment | 4 |
| engine_condition_pushdown | OFF |
| expire_logs_days | 0 |
| flush | OFF |
| flush_time | 0 | |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| group_concat_max_len | 1024 |
| have_archive | YES |
| have_bdb | NO |
| have_blackhole_engine | NO |
| have_compress | YES |
| have_crypt | YES |
| have_csv | NO |
| have_example_engine | NO |
| have_federated_engine | NO |
| have_geometry | YES |
| have_innodb | YES |
| have_isam | NO |
| have_ndbcluster | NO |
| have_openssl | NO |
| have_query_cache | YES |
| have_raid | NO |
| have_rtree_keys | YES |
| have_symlink | YES |
| init_connect | |
| init_file | |
| init_slave | |
| innodb_additional_mem_pool_size | 10485760 |
| innodb_autoextend_increment | 8 |
| innodb_buffer_pool_awe_mem_mb | 0 |
| innodb_buffer_pool_size | 73400320 |
| innodb_checksums | ON |
| innodb_commit_concurrency | 0 |
| innodb_concurrency_tickets | 500 |
| innodb_data_file_path | InnoDB:100M:autoextend |
| innodb_data_home_dir | /usr/local/mysql/data/ |
| innodb_doublewrite | ON |
| innodb_fast_shutdown | 1 |
| innodb_file_io_threads | 4 |
| innodb_file_per_table | OFF |
| innodb_flush_log_at_trx_commit | 1 |
| innodb_flush_method | |
| innodb_force_recovery | 0 |
| innodb_lock_wait_timeout | 50 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_arch_dir | /usr/local/mysql/data |
| innodb_log_archive | OFF |
| innodb_log_buffer_size | 8388608 |
| innodb_log_file_size | 20971520 |
| innodb_log_files_in_group | 2 |
| innodb_log_group_home_dir | /usr/local/mysql/data |
| innodb_max_dirty_pages_pct | 90 |
| innodb_max_purge_lag | 0 |
| innodb_mirrored_log_groups | 1 |
| innodb_open_files | 300 |
| innodb_support_xa | ON |
| innodb_sync_spin_loops | 20 |
| innodb_table_locks | ON |
| innodb_thread_concurrency | 20 |
| innodb_thread_sleep_delay | 10000 |
| interactive_timeout | 28800 |
| join_buffer_size | 131072 |
| key_buffer_size | 268435456 |
| key_cache_age_threshold | 300 |
| key_cache_block_size | 1024 |
| key_cache_division_limit | 100 |
| language | /usr/local/mysql-standard-5.0.18-linux-x86_64-glibc23/share/mysql/english/ |
| large_files_support | ON |
| large_page_size | 0 |
| large_pages | OFF |
| license | GPL |
| local_infile | ON |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | ON |
| log_bin_trust_function_creators | OFF |
| log_error | /var/log/mysql/mysql-error.log |
| log_slave_updates | OFF |
| log_slow_queries | OFF |
| log_warnings | 1 |
| long_query_time | 10 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 1048576 |
| max_binlog_cache_size | 18446744073709551615 |
| max_binlog_size | 1073741824 |
| max_connect_errors | 10 |
| max_connections | 500 |
| max_delayed_threads | 20 |
| max_error_count | 64 |
| max_heap_table_size | 16777216 |
| max_insert_delayed_threads | 20 |
| max_join_size | 18446744073709551615 |
| max_length_for_sort_data | 1024 |
| max_relay_log_size | 0 |
| max_seeks_for_key | 18446744073709551615 |
| max_sort_length | 1024 |
| max_sp_recursion_depth | 0 |
| max_tmp_tables | 32 |
| max_user_connections | 0 |
| max_write_lock_count | 18446744073709551615 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 9223372036854775807 |
| myisam_recover_options | OFF |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 8388608 |
| myisam_stats_method | nulls_unequal |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old_passwords | OFF |
| open_files_limit | 2510 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| pid_file | /usr/local/mysql/data/ProductionLinux.pid |
| port | 3306 |
| preload_buffer_size | 32768 |
| protocol_version | 10 |
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 0 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| range_alloc_block_size | 2048 |
| read_buffer_size | 1044480 |
| read_only | OFF |
| read_rnd_buffer_size | 262144 |
| relay_log_purge | ON |
| relay_log_space_limit | 0 |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| server_id | 71 |
| skip_external_locking | ON |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_load_tmpdir | /tmp/ |
| slave_net_timeout | 3600 |
| slave_skip_errors | OFF |
| slave_transaction_retries | 10 |
| slow_launch_time | 2 |
| socket | /tmp/mysql.sock |
| sort_buffer_size | 4194296 |
| sql_mode | |
| sql_notes | ON |
| sql_warnings | ON |
| storage_engine | MyISAM |
| sync_binlog | 0 |
| sync_frm | ON |
| sync_replication | 0 |
| sync_replication_slave_id | 0 |
| sync_replication_timeout | 10 |
| system_time_zone | CST |
| table_cache | 256 |
| table_lock_wait_timeout | 50 |
| table_type | MyISAM |
| thread_cache_size | 30 |
| thread_stack | 262144 |
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| tmp_table_size | 33554432 |
| tmpdir | |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| updatable_views_with_limit | YES |
| version | 5.0.18-standard-log |
| version_comment | MySQL Community Edition - Standard (GPL) |
| version_compile_machine | x86_64 |
| version_compile_os | unknown-linux-gnu |
| wait_timeout | 28800 |
+---------------------------------+-----------------------------------------------------------------------------+
210 rows in set (0.00 sec)
Your server has probably few cores. (4 ? ) when sql runs at 25% it runs 100% on a single core, if you want it to run "faster" you need to work in parallel, I don't know how it's done in mysql, MS has some parallel execution features in their server.
I guess it depends on your application. If it only uses one connection to the server all queries to the database will be handled from one database thread.
This database server thread will run on one core of the quadcore cpu, so it will only use 25% of the cpu.
I have a production server clocking about 4 million page views per month. The server has got 8GB of RAM and mysql acts as a database.
I am facing problems in handling mysql to take this load. I need to restart mysql twice a day to handle this thing. The problem with mysql is that it starts with some particular occupation, the memory consumed by mysql keeps on increasing untill it reaches the maximum it can consume and then mysql stops responding slowly or does not respond at all, which freezes the server.
All my tables are indexed properly and there are no long queries. I need some one to help on how to go about debugging what to do here.
All my tables are myisam.
I have tried configuring the parameters key_buffer etc but to no rescue. Any sort of help is greatly appreciated. Here are some parameters which may help.
mysql --version
mysql Ver 14.12 Distrib 5.0.77, for redhat-linux-gnu (i686) using readline 5.1
mysql> show variables;
+---------------------------------+------------------------------------------------------------+
| Variable_name | Value |
+---------------------------------+------------------------------------------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr/ |
| bdb_cache_size | 8384512 |
| bdb_home | /var/lib/mysql/ |
| bdb_log_buffer_size | 262144 |
| bdb_logdir | |
| bdb_max_lock | 10000 |
| bdb_shared_data | OFF |
| bdb_tmpdir | /tmp/ |
| binlog_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
| completion_type | 0 |
| concurrent_insert | 1 |
| connect_timeout | 10 |
| datadir | /var/lib/mysql/ |
| date_format | %Y-%m-%d |
| datetime_format | %Y-%m-%d %H:%i:%s |
| default_week_format | 0 |
| delay_key_write | ON |
| delayed_insert_limit | 100 |
| delayed_insert_timeout | 300 |
| delayed_queue_size | 1000 |
| div_precision_increment | 4 |
| keep_files_on_create | OFF |
| engine_condition_pushdown | OFF |
| expire_logs_days | 0 |
| flush | OFF |
| flush_time | 0 |
| ft_boolean_syntax | + -><()~*:""&| |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| group_concat_max_len | 1024 |
| have_archive | NO |
| have_bdb | YES |
| have_blackhole_engine | NO |
| have_compress | YES |
| have_crypt | YES |
| have_csv | NO |
| have_dynamic_loading | YES |
| have_example_engine | NO |
| have_federated_engine | NO |
| have_geometry | YES |
| have_innodb | YES |
| have_isam | NO |
| have_merge_engine | YES |
| have_ndbcluster | NO |
| have_openssl | DISABLED |
| have_ssl | DISABLED |
| have_query_cache | YES |
| have_raid | NO |
| have_rtree_keys | YES |
| have_symlink | YES | |
| init_connect | |
| init_file | |
| init_slave | |
| interactive_timeout | 28800 |
| join_buffer_size | 131072 |
| key_buffer_size | 2621440000 |
| key_cache_age_threshold | 300 |
| key_cache_block_size | 1024 |
| key_cache_division_limit | 100 |
| language | /usr/share/mysql/english/ |
| large_files_support | ON |
| large_page_size | 0 |
| large_pages | OFF |
| lc_time_names | en_US |
| license | GPL |
| local_infile | ON |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | ON |
| log_bin_trust_function_creators | OFF |
| log_error | |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_queries | ON |
| log_warnings | 1 |
| long_query_time | 8 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 8388608 |
| max_binlog_cache_size | 4294963200 |
| max_binlog_size | 1073741824 |
| max_connect_errors | 10 |
| max_connections | 400 |
| max_delayed_threads | 20 |
| max_error_count | 64 |
| max_heap_table_size | 16777216 |
| max_insert_delayed_threads | 20 |
| max_join_size | 4294967295 |
| max_length_for_sort_data | 1024 |
| max_prepared_stmt_count | 16382 |
| max_relay_log_size | 0 |
| max_seeks_for_key | 4294967295 |
| max_sort_length | 1024 |
| max_sp_recursion_depth | 0 |
| max_tmp_tables | 32 |
| max_user_connections | 0 |
| max_write_lock_count | 4294967295 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 2146435072 |
| myisam_recover_options | OFF |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 16777216 |
| myisam_stats_method | nulls_unequal |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old_passwords | OFF |
| open_files_limit | 2000 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| pid_file | /var/run/mysqld/mysqld.pid |
| plugin_dir | |
| port | 3306 |
| preload_buffer_size | 32768 |
| profiling | OFF |
| profiling_history_size | 15 |
| protocol_version | 10 |
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 134217728 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| range_alloc_block_size | 4096 |
| read_buffer_size | 2097152 |
| read_only | OFF |
| read_rnd_buffer_size | 8388608 |
| relay_log | |
| relay_log_index | |
| relay_log_info_file | relay-log.info |
| relay_log_purge | ON |
| relay_log_space_limit | 0 |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| secure_file_priv | |
| server_id | 1 |
| skip_external_locking | ON |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_load_tmpdir | /tmp/ |
| slave_net_timeout | 3600 |
| slave_skip_errors | OFF |
| slave_transaction_retries | 10 |
| slow_launch_time | 2 |
| socket | /var/lib/mysql/mysql.sock |
| sort_buffer_size | 2097152 |
| sql_big_selects | ON |
| sql_mode | |
| sql_notes | ON |
| sql_warnings | OFF |
| ssl_ca | |
| ssl_capath | |
| ssl_cert | |
| ssl_cipher | |
| ssl_key | |
| storage_engine | MyISAM |
| sync_binlog | 0 |
| sync_frm | ON |
| system_time_zone | CST |
| table_cache | 256 |
| table_lock_wait_timeout | 50 |
| table_type | MyISAM |
| thread_cache_size | 8 |
| thread_stack | 196608 |
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| tmp_table_size | 33554432 |
| tmpdir | /tmp/ |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| updatable_views_with_limit | YES |
| version | 5.0.77-log |
| version_bdb | Sleepycat Software: Berkeley DB 4.1.24: (January 29, 2009) |
| version_comment | Source distribution |
| version_compile_machine | i686 |
| version_compile_os | redhat-linux-gnu |
| wait_timeout | 28800 |
+---------------------------------+------------------------------------------------------------+
You have your key_buffer set to 2.5Gb, right?
And this is a 32-bit system.
Are you joking?
You really, really need to use a 64-bit OS if you plan to run MySQL on a server. Otherwise, you cannot reasonably use enough ram. It is probably running out of address space, not memory. This causes problems as you've seen.
The maximum address space that a process can use in 32-bit Linux is typically around 3G. You're blowing most of that on your oversized key buffer, leaving little breathing room.
As a temporary workaround, decrease the key buffer a lot. You should definitely start monitoring the VM usage until you can migrate to 64-bit.
You are making an awful lot of assertions there.
And you've not said what is generating the queries / consuming the data.
While it is possible that MySQL has an undocumented memory leak - thats one problem which I have never experienced with it.
The first thing I would be doing is to look at top sorted by memory to see what's using lots of memory / whats grabbing more memory. I suspect you may find its the clients not releasing result sets correctly that may be causing the problem.