我有一个使用mysqls查询缓存能力的大型数据库应用程序.我想检查查询缓存的内容,以识别不应缓存的条目(例如,通过使用SELECT SQL_NO_CACHE ...),因为我想优化我的应用程序.
有没有办法从查询缓存中获取缓存条目列表？
- 编辑:Rick建议的附加信息---
1)RAM大小为16GB
2)显示变量;
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 bulk_insert_buffer_size 4294967296 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 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 engine_condition_pushdown ON error_count 0 event_scheduler ON expire_logs_days 0 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/run/mysqld/mysqld.log group_concat_max_len 1024 have_community_features YES 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 NO have_query_cache YES have_rtree_keys YES have_ssl DISABLED have_symlink YES hostname www2 identity 0 ignore_builtin_innodb ON init_connect init_file init_slave innodb_adaptive_flushing ON innodb_adaptive_hash_index ON innodb_additional_mem_pool_size 67108864 innodb_autoextend_increment 8 innodb_autoinc_lock_mode 1 innodb_buffer_pool_size 1073741824 innodb_change_buffering inserts 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 Barracuda innodb_file_per_table ON innodb_flush_log_at_trx_commit 1 innodb_flush_method innodb_force_recovery 0 innodb_io_capacity 200 innodb_lock_wait_timeout 50 innodb_locks_unsafe_for_binlog OFF innodb_log_buffer_size 67108864 innodb_log_file_size 268435456 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_read_ahead_threshold 56 innodb_read_io_threads 4 innodb_replication_delay 0 innodb_rollback_on_timeout OFF 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_sys_malloc ON innodb_version 1.0.15 innodb_write_io_threads 4 insert_id 0 interactive_timeout 30 join_buffer_size 2147483648 keep_files_on_create OFF key_buffer_size 4294967296 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 last_insert_id 0 lc_time_names en_US license GPL local_infile OFF locked_in_memory OFF log OFF log_bin OFF log_bin_trust_function_creators OFF log_bin_trust_routine_creators OFF log_error /var/log/mysql/mysqld.err log_output FILE log_queries_not_using_indexes OFF log_slave_updates OFF log_slow_queries ON log_warnings 2 long_query_time 2.000000 low_priority_updates OFF lower_case_file_system OFF lower_case_table_names 0 max_allowed_packet 268435456 max_binlog_cache_size 18446744073709547520 max_binlog_size 1073741824 max_connect_errors 100000 max_connections 120 max_delayed_threads 20 max_error_count 64 max_heap_table_size 268435456 max_insert_delayed_threads 20 max_join_size 18446744073709551615 max_length_for_sort_data 1024 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 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 4294967296 myisam_stats_method nulls_unequal myisam_use_mmap OFF net_buffer_length 1048576 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 8322 optimizer_prune_level 1 optimizer_search_depth 62 optimizer_switch index_merge=on,index_merge_union=on,index_merge_so... pid_file /var/run/mysqld/mysqld.pid plugin_dir /usr/lib64/mysql/plugin port 3306 preload_buffer_size 32768 protocol_version 10 pseudo_thread_id 3468076 query_alloc_block_size 8192 query_cache_limit 4294967296 query_cache_min_res_unit 4096 query_cache_size 1073741824 query_cache_type ON query_cache_wlock_invalidate OFF query_prealloc_size 8192 rand_seed1 rand_seed2 range_alloc_block_size 4096 read_buffer_size 131072 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 report_host report_password report_port 3306 report_user rpl_recovery_rank 0 secure_auth OFF secure_file_priv server_id 0 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 /var/tmp/ slave_net_timeout 3600 slave_skip_errors OFF slave_transaction_retries 10 slow_launch_time 2 slow_query_log ON slow_query_log_file /var/log/mysql/slowqueries.log socket /var/run/mysqld/mysqld.sock sort_buffer_size 262144 sql_auto_is_null ON sql_big_selects ON sql_big_tables OFF sql_buffer_result OFF sql_log_bin ON sql_log_off OFF sql_log_update ON 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 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 CEST table_definition_cache 256 table_lock_wait_timeout 50 table_open_cache 4096 table_type MyISAM thread_cache_size 16 thread_handling one-thread-per-connection thread_stack 262144 time_format %H:%i:%s time_zone SYSTEM timed_mutexes OFF timestamp 1449649902 tmp_table_size 2147483648 tmpdir /var/tmp/ transaction_alloc_block_size 8192 transaction_prealloc_size 4096 tx_isolation READ-COMMITTED unique_checks ON updatable_views_with_limit YES version 5.1.56-log version_comment Gentoo Linux mysql-5.1.56 version_compile_machine x86_64 version_compile_os pc-linux-gnu wait_timeout 30 warning_count 0
3)显示全球状态;
Aborted_clients 2094 Aborted_connects 4 Binlog_cache_disk_use 0 Binlog_cache_use 0 Bytes_received 171903979482 Bytes_sent 2515206884666 Com_admin_commands 339464 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 340 Com_alter_tablespace 0 Com_analyze 0 Com_backup_table 0 Com_begin 5508 Com_binlog 0 Com_call_procedure 0 Com_change_db 3205067 Com_change_master 0 Com_check 2735 Com_checksum 0 Com_commit 5508 Com_create_db 1 Com_create_event 0 Com_create_function 0 Com_create_index 0 Com_create_procedure 0 Com_create_server 0 Com_create_table 148 Com_create_trigger 0 Com_create_udf 0 Com_create_user 0 Com_create_view 0 Com_dealloc_sql 2 Com_delete 10465739 Com_delete_multi 15995 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 121 Com_drop_trigger 0 Com_drop_user 0 Com_drop_view 0 Com_empty_query 0 Com_execute_sql 2 Com_flush 342 Com_grant 2 Com_ha_close 0 Com_ha_open 0 Com_ha_read 0 Com_help 0 Com_insert 13583029 Com_insert_select 409 Com_install_plugin 0 Com_kill 0 Com_load 112042 Com_load_master_data 0 Com_load_master_table 0 Com_lock_tables 2068 Com_optimize 44 Com_preload_keys 0 Com_prepare_sql 2 Com_purge 0 Com_purge_before_date 0 Com_release_savepoint 0 Com_rename_table 0 Com_rename_user 0 Com_repair 2 Com_replace 489 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 115580660 Com_set_option 6028458 Com_show_authors 0 Com_show_binlog_events 0 Com_show_binlogs 11 Com_show_charsets 128 Com_show_collations 105 Com_show_column_types 0 Com_show_contributors 0 Com_show_create_db 10 Com_show_create_event 0 Com_show_create_func 0 Com_show_create_proc 0 Com_show_create_table 172358 Com_show_create_trigger 0 Com_show_databases 3956 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 839418 Com_show_function_status 0 Com_show_grants 11 Com_show_keys 3212 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 2 Com_show_profile 0 Com_show_profiles 0 Com_show_slave_hosts 0 Com_show_slave_status 0 Com_show_status 31038 Com_show_storage_engines 0 Com_show_table_status 207707 Com_show_tables 55951 Com_show_triggers 172340 Com_show_variables 803242 Com_show_warnings 0 Com_slave_start 0 Com_slave_stop 0 Com_stmt_close 627128 Com_stmt_execute 627128 Com_stmt_fetch 0 Com_stmt_prepare 627128 Com_stmt_reprepare 0 Com_stmt_reset 0 Com_stmt_send_long_data 0 Com_truncate 4722 Com_uninstall_plugin 0 Com_unlock_tables 2068 Com_update 1754805 Com_update_multi 1 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 3467815 Created_tmp_disk_tables 2151917 Created_tmp_files 16517 Created_tmp_tables 3928177 Delayed_errors 0 Delayed_insert_threads 0 Delayed_writes 0 Flush_commands 1 Handler_commit 90276170 Handler_delete 9422032 Handler_discover 0 Handler_prepare 0 Handler_read_first 16985165 Handler_read_key 727922287 Handler_read_next 1575370461 Handler_read_prev 1178376 Handler_read_rnd 114364819 Handler_read_rnd_next 40377965120 Handler_rollback 326 Handler_savepoint 0 Handler_savepoint_rollback 0 Handler_update 33675553 Handler_write 137057026 Innodb_buffer_pool_pages_data 65003 Innodb_buffer_pool_pages_dirty 44 Innodb_buffer_pool_pages_flushed 29673396 Innodb_buffer_pool_pages_free 1 Innodb_buffer_pool_pages_misc 531 Innodb_buffer_pool_pages_total 65535 Innodb_buffer_pool_read_ahead 30144135 Innodb_buffer_pool_read_ahead_evicted 4691916 Innodb_buffer_pool_read_requests 5269018735 Innodb_buffer_pool_reads 15291059 Innodb_buffer_pool_wait_free 0 Innodb_buffer_pool_write_requests 196667000 Innodb_data_fsyncs 23264996 Innodb_data_pending_fsyncs 1 Innodb_data_pending_reads 0 Innodb_data_pending_writes 0 Innodb_data_read 745229520896 Innodb_data_reads 15847178 Innodb_data_writes 40737707 Innodb_data_written 1007283227136 Innodb_dblwr_pages_written 29673396 Innodb_dblwr_writes 727171 Innodb_have_atomic_builtins ON Innodb_log_waits 0 Innodb_log_write_requests 61077243 Innodb_log_writes 17124326 Innodb_os_log_fsyncs 17565254 Innodb_os_log_pending_fsyncs 1 Innodb_os_log_pending_writes 0 Innodb_os_log_written 34746359296 Innodb_page_size 16384 Innodb_pages_created 893340 Innodb_pages_read 45485066 Innodb_pages_written 29673396 Innodb_row_lock_current_waits 0 Innodb_row_lock_time 75432 Innodb_row_lock_time_avg 23 Innodb_row_lock_time_max 10927 Innodb_row_lock_waits 3264 Innodb_rows_deleted 8649356 Innodb_rows_inserted 12313551 Innodb_rows_read 3890223870 Innodb_rows_updated 1493452 Key_blocks_not_flushed 0 Key_blocks_unused 3089739 Key_blocks_used 864035 Key_read_requests 1336336475 Key_reads 2772018 Key_write_requests 105012022 Key_writes 7764232 Last_query_cost 0.000000 Max_used_connections 69 Not_flushed_delayed_rows 0 Open_files 3006 Open_streams 0 Open_table_definitions 2265 Open_tables 3982 Opened_files 16841374 Opened_table_definitions 140845 Opened_tables 327918 Prepared_stmt_count 0 Qcache_free_blocks 56315 Qcache_free_memory 164432360 Qcache_hits 539352560 Qcache_inserts 111849501 Qcache_lowmem_prunes 54731591 Qcache_not_cached 3376334 Qcache_queries_in_cache 182383 Qcache_total_blocks 472186 Queries 697132110 Questions 695877858 Rpl_status NULL Select_full_join 30156 Select_full_range_join 4732 Select_range 36065208 Select_range_check 76799 Select_scan 4058097 Slave_open_temp_tables 0 Slave_retried_transactions 0 Slave_running OFF Slow_launch_threads 0 Slow_queries 13817 Sort_merge_passes 24563 Sort_range 2573998 Sort_rows 93946492 Sort_scan 1603263 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 157822475 Table_locks_waited 3513 Tc_log_max_pages_used 0 Tc_log_page_size 0 Tc_log_page_waits 0 Threads_cached 14 Threads_connected 3 Threads_created 2076 Threads_running 3 Uptime 4656056 Uptime_since_flush_status 4656056
Rick James.. 8
观察结果：
版本：5.1.56-log
16 GB的RAM
正常运行时间= 53d 21:20:56
您未在Windows上运行。
运行64位版本
看来您正在同时运行MyISAM和InnoDB。
更重要的问题
key_buffer_size = 1500M innodb_buffer_pool_size = 2000M join_buffer_size = 1M -- This may be the most important tmp_table_size = 256M -- Also important query_cache_size = 50M -- as already mentioned Use slowlog to find tmp tables spilling to disk
三种设置特别高，可能导致分页/交换。分页/交换时，MySQL的性能将遭受极大的损害。降低设置比发生这种情况更好。
细节和次要问题
（innodb_buffer_pool_size / _ram）= 1024M / 16384M = 6.2％-用于InnoDB buffer_pool的RAM的百分比
（Innodb_pages_write / Innodb_buffer_pool_write_requests）= 29,673,396 / 196667000 = 15.1％-写入必须打到磁盘的请求-检查innodb_buffer_pool_size
（Innodb_buffer_pool_read_ahead_evicted / Innodb_buffer_pool_read_ahead）= 4,691,916 / 30144135 = 15.6％-read_ahead的实用程序。-关闭预读
（Innodb_os_log_write /（正常运行时间/ 3600）/ innodb_log_files_in_group / innodb_log_file_size）= 34,746,359,296 /（4656056/3600）/ 2 / 256M = 0.05-比率
（正常运行时间/ 60 * innodb_log_file_size / Innodb_os_log_write）= 4,656,056 / 60 * 256M / 34746359296 = 599-InnoDB日志轮换之间的分钟数从5.6.8开始，可以动态更改; 一定还要更改my.cnf。-（建议每轮间隔60分钟有点随意）。
（table_open_cache）= 4,096-要缓存的表描述符的数量-通常好几百个。
（innodb_stats_on_metadata）= ON-触摸统计信息时重新分析表。-ON可能会减慢某些SHOW和information_schema访问的速度。
（join_buffer_size）= 2,147,483,648 = 2048MB-每个线程0-N。可能会加速JOIN（更好地修复查询/索引）（所有引擎）（用于索引扫描，范围索引扫描，全表扫描，每个完整JOIN等）-使用默认值。
（join_buffer_size / _ram）= 2,147,483,648 / 16384M = 12.5％-每个线程0-N。可能会加速JOIN（更好地修复查询/索引）（所有引擎）（用于索引扫描，范围索引扫描，全表扫描，每个完整JOIN等）。-减小join_buffer_size以避免内存压力。建议少于1％的RAM。
（min（tmp_table_size，max_heap_table_size）/ _ram）= min（2147483648，256M）/ 16384M = 1.6％-需要MEMORY表（每个表）或SELECT内的临时表（每个临时表每个）时要分配的RAM百分比选择）。太高可能导致交换。-将tmp_table_size和max_heap_table_size减小为ram的1％。
（（key_buffer_size-1.2 * Key_blocks_used * 1024）/ _ram）=（4294967296-1.2 * 864035 * 1024）/ 16384M = 18.8％-key_buffer中浪费了RAM的百分比。-减少key_buffer_size
（Key_blocks_used * 1024 / key_buffer_size）= 864,035 * 1024/4294967296 = 20.6％-使用的key_buffer的百分比。高水位标记。-降低key_buffer_size以避免不必要的内存使用。
（Key_writes / Key_write_requests）= 7,764,232 / 105012022 = 7.4％-写入的key_buffer有效性
（query_cache_size）= 1024M-QC的大小-太小=没有太大用处。太大=过多的开销。推荐0或不超过50M。
（Created_tmp_disk_tables /（Created_tmp_disk_tables + Created_tmp_tables））= 2,151,917 /（2151917 + 3928177）= 35.4％-溢出到磁盘的临时表的百分比
（tmp_table_size）= 2,147,483,648 = 2048MB- 用于支持SELECT 的MEMORY临时表的大小限制-减小tmp_table_size以避免RAM耗尽。也许不超过64M。
（back_log / max_connections）= 50/120 = 41.7％
（max_connect_errors）= 100,000-一种针对黑客的小防护。-可能不超过200。
观察结果：
版本：5.1.56-log
16 GB的RAM
正常运行时间= 53d 21:20:56
您未在Windows上运行。
运行64位版本
看来您正在同时运行MyISAM和InnoDB。
更重要的问题
key_buffer_size = 1500M innodb_buffer_pool_size = 2000M join_buffer_size = 1M -- This may be the most important tmp_table_size = 256M -- Also important query_cache_size = 50M -- as already mentioned Use slowlog to find tmp tables spilling to disk
三种设置特别高，可能导致分页/交换。分页/交换时，MySQL的性能将遭受极大的损害。降低设置比发生这种情况更好。
细节和次要问题
（innodb_buffer_pool_size / _ram）= 1024M / 16384M = 6.2％-用于InnoDB buffer_pool的RAM的百分比
（Innodb_pages_write / Innodb_buffer_pool_write_requests）= 29,673,396 / 196667000 = 15.1％-写入必须打到磁盘的请求-检查innodb_buffer_pool_size
（Innodb_buffer_pool_read_ahead_evicted / Innodb_buffer_pool_read_ahead）= 4,691,916 / 30144135 = 15.6％-read_ahead的实用程序。-关闭预读
（Innodb_os_log_write /（正常运行时间/ 3600）/ innodb_log_files_in_group / innodb_log_file_size）= 34,746,359,296 /（4656056/3600）/ 2 / 256M = 0.05-比率
（正常运行时间/ 60 * innodb_log_file_size / Innodb_os_log_write）= 4,656,056 / 60 * 256M / 34746359296 = 599-InnoDB日志轮换之间的分钟数从5.6.8开始，可以动态更改; 一定还要更改my.cnf。-（建议每轮间隔60分钟有点随意）。
（table_open_cache）= 4,096-要缓存的表描述符的数量-通常好几百个。
（innodb_stats_on_metadata）= ON-触摸统计信息时重新分析表。-ON可能会减慢某些SHOW和information_schema访问的速度。
（join_buffer_size）= 2,147,483,648 = 2048MB-每个线程0-N。可能会加速JOIN（更好地修复查询/索引）（所有引擎）（用于索引扫描，范围索引扫描，全表扫描，每个完整JOIN等）-使用默认值。
（join_buffer_size / _ram）= 2,147,483,648 / 16384M = 12.5％-每个线程0-N。可能会加速JOIN（更好地修复查询/索引）（所有引擎）（用于索引扫描，范围索引扫描，全表扫描，每个完整JOIN等）。-减小join_buffer_size以避免内存压力。建议少于1％的RAM。
（min（tmp_table_size，max_heap_table_size）/ _ram）= min（2147483648，256M）/ 16384M = 1.6％-需要MEMORY表（每个表）或SELECT内的临时表（每个临时表每个）时要分配的RAM百分比选择）。太高可能导致交换。-将tmp_table_size和max_heap_table_size减小为ram的1％。
（（key_buffer_size-1.2 * Key_blocks_used * 1024）/ _ram）=（4294967296-1.2 * 864035 * 1024）/ 16384M = 18.8％-key_buffer中浪费了RAM的百分比。-减少key_buffer_size
（Key_blocks_used * 1024 / key_buffer_size）= 864,035 * 1024/4294967296 = 20.6％-使用的key_buffer的百分比。高水位标记。-降低key_buffer_size以避免不必要的内存使用。
（Key_writes / Key_write_requests）= 7,764,232 / 105012022 = 7.4％-写入的key_buffer有效性
（query_cache_size）= 1024M-QC的大小-太小=没有太大用处。太大=过多的开销。推荐0或不超过50M。
（Created_tmp_disk_tables /（Created_tmp_disk_tables + Created_tmp_tables））= 2,151,917 /（2151917 + 3928177）= 35.4％-溢出到磁盘的临时表的百分比
（tmp_table_size）= 2,147,483,648 = 2048MB- 用于支持SELECT 的MEMORY临时表的大小限制-减小tmp_table_size以避免RAM耗尽。也许不超过64M。
（back_log / max_connections）= 50/120 = 41.7％
（max_connect_errors）= 100,000-一种针对黑客的小防护。-可能不超过200。
您可以知道缓存的查询量
Show status like 'Qcache_queries_in_cache'
它将为您提供value列中的缓存查询量.只有查询的哈希值存储在Qcache中.无法找到实际缓存的查询.了解它的一种可能方法是执行一个查询并检查value列的更改.
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