我有一个非常简单的查询，它在我的开发机器上运行时间为 216 毫秒，但在我的生产服务器上却花费了超过 45 秒，直到我在那里重新启动 MySQL：
UPDATE `forum_categories` SET `post_count` = COALESCE(`post_count`, 0) + 1 WHERE (`id` = 20)
这是SHOW STATUS重新启动之前的值：
+-----------------------------------+--------------+
| Variable_name | Value |
+-----------------------------------+--------------+
| Aborted_clients | 356 |
| Aborted_connects | 1 |
| Binlog_cache_disk_use | 0 |
| Binlog_cache_use | 0 |
| Bytes_received | 288 |
| Bytes_sent | 17160 |
| Com_admin_commands | 0 |
| Com_assign_to_keycache | 0 |
| Com_alter_db | 0 |
| Com_alter_db_upgrade | 0 |
| Com_alter_event | 0 |
| Com_alter_function | 0 |
| Com_alter_procedure | 0 |
| Com_alter_server | 0 |
| Com_alter_table | 0 |
| Com_alter_tablespace | 0 |
| Com_analyze | 0 |
| Com_backup_table | 0 |
| Com_begin | 0 |
| Com_binlog | 0 |
| Com_call_procedure | 0 |
| Com_change_db | 0 |
| Com_change_master | 0 |
| Com_check | 0 |
| Com_checksum | 0 |
| Com_commit | 0 |
| Com_create_db | 0 |
| Com_create_event | 0 |
| Com_create_function | 0 |
| Com_create_index | 0 |
| Com_create_procedure | 0 |
| Com_create_server | 0 |
| Com_create_table | 0 |
| Com_create_trigger | 0 |
| Com_create_udf | 0 |
| Com_create_user | 0 |
| Com_create_view | 0 |
| Com_dealloc_sql | 0 |
| Com_delete | 0 |
| Com_delete_multi | 0 |
| Com_do | 0 |
| Com_drop_db | 0 |
| Com_drop_event | 0 |
| Com_drop_function | 0 |
| Com_drop_index | 0 |
| Com_drop_procedure | 0 |
| Com_drop_server | 0 |
| Com_drop_table | 0 |
| Com_drop_trigger | 0 |
| Com_drop_user | 0 |
| Com_drop_view | 0 |
| Com_empty_query | 0 |
| Com_execute_sql | 0 |
| Com_flush | 0 |
| Com_grant | 0 |
| Com_ha_close | 0 |
| Com_ha_open | 0 |
| Com_ha_read | 0 |
| Com_help | 0 |
| Com_insert | 0 |
| Com_insert_select | 0 |
| Com_install_plugin | 0 |
| Com_kill | 0 |
| Com_load | 0 |
| Com_load_master_data | 0 |
| Com_load_master_table | 0 |
| Com_lock_tables | 0 |
| Com_optimize | 0 |
| Com_preload_keys | 0 |
| Com_prepare_sql | 0 |
| Com_purge | 0 |
| Com_purge_before_date | 0 |
| Com_release_savepoint | 0 |
| Com_rename_table | 0 |
| Com_rename_user | 0 |
| Com_repair | 0 |
| Com_replace | 0 |
| Com_replace_select | 0 |
| Com_reset | 0 |
| Com_restore_table | 0 |
| Com_revoke | 0 |
| Com_revoke_all | 0 |
| Com_rollback | 0 |
| Com_rollback_to_savepoint | 0 |
| Com_savepoint | 0 |
| Com_select | 1 |
| Com_set_option | 0 |
| Com_show_authors | 0 |
| Com_show_binlog_events | 0 |
| Com_show_binlogs | 0 |
| Com_show_charsets | 0 |
| Com_show_collations | 0 |
| Com_show_column_types | 0 |
| Com_show_contributors | 0 |
| Com_show_create_db | 0 |
| Com_show_create_event | 0 |
| Com_show_create_func | 0 |
| Com_show_create_proc | 0 |
| Com_show_create_table | 0 |
| Com_show_create_trigger | 0 |
| Com_show_databases | 0 |
| Com_show_engine_logs | 0 |
| Com_show_engine_mutex | 0 |
| Com_show_engine_status | 0 |
| Com_show_events | 0 |
| Com_show_errors | 0 |
| Com_show_fields | 0 |
| Com_show_function_status | 0 |
| Com_show_grants | 0 |
| Com_show_keys | 0 |
| Com_show_master_status | 0 |
| Com_show_new_master | 0 |
| Com_show_open_tables | 0 |
| Com_show_plugins | 0 |
| Com_show_privileges | 0 |
| Com_show_procedure_status | 0 |
| Com_show_processlist | 8 |
| Com_show_profile | 0 |
| Com_show_profiles | 0 |
| Com_show_slave_hosts | 0 |
| Com_show_slave_status | 0 |
| Com_show_status | 1 |
| Com_show_storage_engines | 0 |
| Com_show_table_status | 0 |
| Com_show_tables | 0 |
| Com_show_triggers | 0 |
| Com_show_variables | 0 |
| Com_show_warnings | 0 |
| Com_slave_start | 0 |
| Com_slave_stop | 0 |
| Com_stmt_close | 0 |
| Com_stmt_execute | 0 |
| Com_stmt_fetch | 0 |
| Com_stmt_prepare | 0 |
| Com_stmt_reprepare | 0 |
| Com_stmt_reset | 0 |
| Com_stmt_send_long_data | 0 |
| Com_truncate | 0 |
| Com_uninstall_plugin | 0 |
| Com_unlock_tables | 0 |
| Com_update | 0 |
| Com_update_multi | 0 |
| Com_xa_commit | 0 |
| Com_xa_end | 0 |
| Com_xa_prepare | 0 |
| Com_xa_recover | 0 |
| Com_xa_rollback | 0 |
| Com_xa_start | 0 |
| Compression | OFF |
| Connections | 486 |
| Created_tmp_disk_tables | 0 |
| Created_tmp_files | 13 |
| Created_tmp_tables | 0 |
| Delayed_errors | 0 |
| Delayed_insert_threads | 0 |
| Delayed_writes | 0 |
| Flush_commands | 1 |
| Handler_commit | 0 |
| Handler_delete | 0 |
| Handler_discover | 0 |
| Handler_prepare | 0 |
| Handler_read_first | 0 |
| Handler_read_key | 0 |
| Handler_read_next | 0 |
| Handler_read_prev | 0 |
| Handler_read_rnd | 0 |
| Handler_read_rnd_next | 0 |
| Handler_rollback | 0 |
| Handler_savepoint | 0 |
| Handler_savepoint_rollback | 0 |
| Handler_update | 0 |
| Handler_write | 0 |
| Innodb_buffer_pool_pages_data | 439 |
| Innodb_buffer_pool_pages_dirty | 16 |
| Innodb_buffer_pool_pages_flushed | 342213 |
| Innodb_buffer_pool_pages_free | 0 |
| Innodb_buffer_pool_pages_misc | 73 |
| Innodb_buffer_pool_pages_total | 512 |
| Innodb_buffer_pool_read_ahead_rnd | 766743 |
| Innodb_buffer_pool_read_ahead_seq | 697962 |
| Innodb_buffer_pool_read_requests | 6614591621 |
| Innodb_buffer_pool_reads | 31600209 |
| Innodb_buffer_pool_wait_free | 0 |
| Innodb_buffer_pool_write_requests | 2122755 |
| Innodb_data_fsyncs | 266343 |
| Innodb_data_pending_fsyncs | 0 |
| Innodb_data_pending_reads | 0 |
| Innodb_data_pending_writes | 0 |
| Innodb_data_read | 796822818816 |
| Innodb_data_reads | 34112076 |
| Innodb_data_writes | 556215 |
| Innodb_data_written | 11420234240 |
| Innodb_dblwr_pages_written | 342213 |
| Innodb_dblwr_writes | 18181 |
| Innodb_log_waits | 0 |
| Innodb_log_write_requests | 221569 |
| Innodb_log_writes | 223375 |
| Innodb_os_log_fsyncs | 230097 |
| Innodb_os_log_pending_fsyncs | 0 |
| Innodb_os_log_pending_writes | 0 |
| Innodb_os_log_written | 203197440 |
| Innodb_page_size | 16384 |
| Innodb_pages_created | 3208 |
| Innodb_pages_read | 48634093 |
| Innodb_pages_written | 342213 |
| Innodb_row_lock_current_waits | 11 |
| Innodb_row_lock_time | 6248224 |
| Innodb_row_lock_time_avg | 27769 |
| Innodb_row_lock_time_max | 51857 |
| Innodb_row_lock_waits | 225 |
| Innodb_rows_deleted | 106967 |
| Innodb_rows_inserted | 109771 |
| Innodb_rows_read | 7740417900 |
| Innodb_rows_updated | 98427 |
| Key_blocks_not_flushed | 0 |
| Key_blocks_unused | 13396 |
| Key_blocks_used | 3 |
| Key_read_requests | 78911 |
| Key_reads | 0 |
| Key_write_requests | 2447 |
| Key_writes | 0 |
| Last_query_cost | 0.000000 |
| Max_used_connections | 31 |
| Not_flushed_delayed_rows | 0 |
| Open_files | 46 |
| Open_streams | 0 |
| Open_table_definitions | 101 |
| Open_tables | 156 |
| Opened_files | 108434 |
| Opened_table_definitions | 0 |
| Opened_tables | 0 |
| Prepared_stmt_count | 0 |
| Qcache_free_blocks | 58150 |
| Qcache_free_memory | 309389896 |
| Qcache_hits | 6750944 |
| Qcache_inserts | 7589394 |
| Qcache_lowmem_prunes | 0 |
| Qcache_not_cached | 487929 |
| Qcache_queries_in_cache | 105847 |
| Qcache_total_blocks | 270852 |
| Queries | 15733827 |
| Questions | 10 |
| Rpl_status | NULL |
| Select_full_join | 0 |
| Select_full_range_join | 0 |
| Select_range | 0 |
| Select_range_check | 0 |
| Select_scan | 0 |
| Slave_open_temp_tables | 0 |
| Slave_retried_transactions | 0 |
| Slave_running | OFF |
| Slow_launch_threads | 0 |
| Slow_queries | 0 |
| Sort_merge_passes | 0 |
| Sort_range | 0 |
| Sort_rows | 0 |
| Sort_scan | 0 |
| Ssl_accept_renegotiates | 0 |
| Ssl_accepts | 0 |
| Ssl_callback_cache_hits | 0 |
| Ssl_cipher | |
| Ssl_cipher_list | |
| Ssl_client_connects | 0 |
| Ssl_connect_renegotiates | 0 |
| Ssl_ctx_verify_depth | 0 |
| Ssl_ctx_verify_mode | 0 |
| Ssl_default_timeout | 0 |
| Ssl_finished_accepts | 0 |
| Ssl_finished_connects | 0 |
| Ssl_session_cache_hits | 0 |
| Ssl_session_cache_misses | 0 |
| Ssl_session_cache_mode | NONE |
| Ssl_session_cache_overflows | 0 |
| Ssl_session_cache_size | 0 |
| Ssl_session_cache_timeouts | 0 |
| Ssl_sessions_reused | 0 |
| Ssl_used_session_cache_entries | 0 |
| Ssl_verify_depth | 0 |
| Ssl_verify_mode | 0 |
| Ssl_version | |
| Table_locks_immediate | 8315915 |
| Table_locks_waited | 0 |
| Tc_log_max_pages_used | 0 |
| Tc_log_page_size | 0 |
| Tc_log_page_waits | 0 |
| Threads_cached | 3 |
| Threads_connected | 28 |
| Threads_created | 31 |
| Threads_running | 13 |
| Uptime | 66323 |
| Uptime_since_flush_status | 66323 |
+-----------------------------------+--------------+
表格架构如下：
mysql> SHOW CREATE TABLE forum_categories\G
*************************** 1. row ***************************
Table: forum_categories
Create Table: CREATE TABLE `forum_categories` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`ancestry` varchar(255) DEFAULT NULL,
`title` varchar(255) NOT NULL,
`description` text,
`position` int(11) DEFAULT '0',
`published` tinyint(1) DEFAULT '1',
`exclusive` tinyint(1) DEFAULT '0',
`show_homepage` tinyint(1) DEFAULT '1',
`created_at` datetime DEFAULT NULL,
`updated_at` datetime DEFAULT NULL,
`post_count` int(11) DEFAULT '0',
`slug` varchar(255) DEFAULT NULL,
`last_post_id` int(11) DEFAULT NULL,
`exclusive_level` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `index_forum_categories_on_ancestry` (`ancestry`),
KEY `index_forum_categories_on_exclusive` (`exclusive`),
KEY `index_forum_categories_on_last_post_id` (`last_post_id`),
KEY `index_forum_categories_on_position` (`position`),
KEY `index_forum_categories_on_published` (`published`),
KEY `index_forum_categories_on_show_homepage` (`show_homepage`),
KEY `index_forum_categories_on_post_count` (`post_count`)
) ENGINE=InnoDB AUTO_INCREMENT=45 DEFAULT CHARSET=utf8
仅供参考-该机器拥有充足的 RAM，并且平均负载通常接近 1。MySQL 版本是 5.1.41。
有什么想法吗？谢谢。
答案1
使用 mysqltuner.pl 并查看它说了什么。