一、 SQL优化

1. 通过show status 命令了解各种SQL的执行频率

mysql>show status like 'Com_%';

+---------------------------+-------+

| Variable_name | Value |

+---------------------------+-------+

| 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_alter_user | 0 |

| Com_analyze | 0 |

| Com_begin | 0 |

| Com_binlog | 0 |

| Com_call_procedure | 0 |

| Com_change_db | 4 |

| Com_change_master | 0 |

| Com_check | 0 |

| Com_checksum | 0 |

| Com_commit | 30 |

| Com_create_db | 1 |

| Com_create_event | 0 |

| Com_create_function | 3 |

| Com_create_index | 0 |

| Com_create_procedure | 3 |

| Com_create_server | 0 |

| Com_create_table | 16 |

| Com_create_trigger | 6 |

| Com_create_udf | 0 |

| Com_create_user | 0 |

| Com_create_view | 7 |

| Com_dealloc_sql | 0 |

| Com_delete | 0 | ——执行delete操作的次数

| Com_delete_multi | 0 |

| Com_do | 0 |

| Com_drop_db | 1 |

| 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_get_diagnostics | 0 |

| Com_grant | 0 |

| Com_ha_close | 0 |

| Com_ha_open | 0 |

| Com_ha_read | 0 |

| Com_help | 0 |

| Com_insert | 1017 | ——执行insert操作次数，批量插入insert只加1

| Com_insert_select | 0 |

| Com_install_plugin | 0 |

| Com_kill | 0 |

| Com_load | 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_resignal | 0 |

| Com_revoke | 0 |

| Com_revoke_all | 0 |

| Com_rollback | 0 |

| Com_rollback_to_savepoint | 0 |

| Com_savepoint | 0 |

| Com_select | 7 | ——执行SELECT操作的次数，每次加1

| Com_set_option | 48 |

| Com_signal | 0 |

| Com_show_binlog_events | 0 |

| Com_show_binlogs | 0 |

| Com_show_charsets | 0 |

| Com_show_collations | 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 |2 |

| 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_code | 0 |

| Com_show_function_status | 0 |

| Com_show_grants | 0 |

| Com_show_keys | 0 |

| Com_show_master_status | 0 |

| Com_show_open_tables | 0 |

| Com_show_plugins | 0 |

| Com_show_privileges | 0 |

| Com_show_procedure_code | 0 |

| Com_show_procedure_status | 0 |

| Com_show_processlist | 0 |

| Com_show_profile | 0 |

| Com_show_profiles | 0 |

| Com_show_relaylog_events | 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 | 2 |

| 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 |