MySql服务器出现问题导致它一直冻结。在phpMyAdmin中，当发生这种情况时，我可以在“显示流程列表”中看到用户“未经身份验证的用户”的许多流程，其中命令为“connect”，状态为“从网络读取”。
数据库正在使用InnoDB，但我还使用一个运行MyISAM的表来执行全文搜索。服务器有大约4GB内存，使用时不到500MB。
我一直在使用来自MySql的慢查询日志来查找不使用索引的查询。我还认为我需要对服务器变量进行一些更改/调整。
我真的可以在这里使用一些帮助，因此我在这里发布了SHOW GLOBAL STATUS和SHOW GLOBAL VARIABLES，也许你可以给我一些如何设置变量的想法？
当前显示全球状态：
Variable_name Value
Aborted_clients 730
Aborted_connects 35
Binlog_cache_disk_use 0
Binlog_cache_use 0
Binlog_stmt_cache_disk_use 0
Binlog_stmt_cache_use 0
Bytes_received 31558148370
Bytes_sent 556410688609
Com_admin_commands 4565
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 3
Com_alter_tablespace 0
Com_analyze 0
Com_begin 168
Com_binlog 0
Com_call_procedure 0
Com_change_db 26791502
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 584152
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 5871056
Com_insert_select 2833
Com_install_plugin 0
Com_kill 160
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 21739455
Com_set_option 53600251
Com_signal 0
Com_show_authors 0
Com_show_binlog_events 0
Com_show_binlogs 217
Com_show_charsets 3
Com_show_collations 26786645
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 6412
Com_show_create_trigger 84
Com_show_databases 213
Variable_name Value
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 4389
Com_show_function_status 14
Com_show_grants 2
Com_show_keys 25
Com_show_master_status 5
Com_show_open_tables 0
Com_show_plugins 560
Com_show_privileges 0
Com_show_procedure_status 14
Com_show_processlist 189
Com_show_profile 0
Com_show_profiles 0
Com_show_relaylog_events 0
Com_show_slave_hosts 0
Com_show_slave_status 5
Com_show_status 156
Com_show_storage_engines 16
Com_show_table_status 4154
Com_show_tables 280
Com_show_triggers 4144
Com_show_variables 26786703
Com_show_warnings 2363
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 168
Com_update 2572452
Com_update_multi 35171
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 26787752
Created_tmp_disk_tables 119645
Created_tmp_files 7069
Created_tmp_tables 58427880
Delayed_errors 0
Delayed_insert_threads 0
Delayed_writes 0
Flush_commands 1
Handler_commit 30698922
Handler_delete 177424
Handler_discover 0
Handler_prepare 0
Handler_read_first 1239039
Handler_read_key 2226723080
Handler_read_last 9200
Handler_read_next 4186985860
Handler_read_prev 6811735740
Handler_read_rnd 8942473
Handler_read_rnd_next 16431972655
Handler_rollback 495
Handler_savepoint 0
Handler_savepoint_rollback 0
Handler_update 9720709
Handler_write 15014651212
Innodb_buffer_pool_pages_data 8173
Innodb_buffer_pool_pages_dirty 138
Innodb_buffer_pool_pages_flushed 34780758
Innodb_buffer_pool_pages_free 0
Innodb_buffer_pool_pages_misc 18
Innodb_buffer_pool_pages_total 8191
Innodb_buffer_pool_read_ahead_rnd 0
Innodb_buffer_pool_read_ahead 26163447
Innodb_buffer_pool_read_ahead_evicted 669245354
Innodb_buffer_pool_read_requests 19793139859
Innodb_buffer_pool_reads 1156881183
Innodb_buffer_pool_wait_free 0
Innodb_buffer_pool_write_requests 81288931
Innodb_data_fsyncs 8482576
Innodb_data_pending_fsyncs 0
Innodb_data_pending_reads 0
Innodb_data_pending_writes 0
Innodb_data_read 19409628139520
Innodb_data_reads 1184668281
Innodb_data_writes 25747879
Innodb_data_written 576917547008
Innodb_dblwr_pages_written 17390379
Innodb_dblwr_writes 255445
Innodb_have_atomic_builtins ON
Innodb_log_waits 0
Innodb_log_write_requests 6930648
Innodb_log_writes 7850155
Innodb_os_log_fsyncs 7976564
Variable_name Value
Innodb_os_log_pending_fsyncs 0
Innodb_os_log_pending_writes 0
Innodb_os_log_written 7007020032
Innodb_page_size 16384
Innodb_pages_created 78647
Innodb_pages_read 1184669628
Innodb_pages_written 17390379
Innodb_row_lock_current_waits 0
Innodb_row_lock_time 1116
Innodb_row_lock_time_avg 39
Innodb_row_lock_time_max 963
Innodb_row_lock_waits 28
Innodb_rows_deleted 177424
Innodb_rows_inserted 5863854
Innodb_rows_read 14138431339
Innodb_rows_updated 4886889
Innodb_truncated_status_writes 0
Key_blocks_not_flushed 0
Key_blocks_unused 13
Key_blocks_used 13
Key_read_requests 3458723878
Key_reads 49092342
Key_write_requests 462162
Key_writes 436874
Last_query_cost 0.000000
Max_used_connections 137
Not_flushed_delayed_rows 0
Open_files 0
Open_streams 0
Open_table_definitions 113
Open_tables 4
Opened_files 6485943
Opened_table_definitions 116
Opened_tables 31771706
Performance_schema_cond_classes_lost 0
Performance_schema_cond_instances_lost 0
Performance_schema_file_classes_lost 0
Performance_schema_file_handles_lost 0
Performance_schema_file_instances_lost 0
Performance_schema_locker_lost 0
Performance_schema_mutex_classes_lost 0
Performance_schema_mutex_instances_lost 0
Performance_schema_rwlock_classes_lost 0
Performance_schema_rwlock_instances_lost 0
Performance_schema_table_handles_lost 0
Performance_schema_table_instances_lost 0
Performance_schema_thread_classes_lost 0
Performance_schema_thread_instances_lost 0
Prepared_stmt_count 0
Qcache_free_blocks 0
Qcache_free_memory 0
Qcache_hits 0
Qcache_inserts 0
Qcache_lowmem_prunes 0
Qcache_not_cached 0
Qcache_queries_in_cache 0
Qcache_total_blocks 0
Queries 191630861
Questions 191562751
Rpl_status AUTH_MASTER
Select_full_join 7193
Select_full_range_join 0
Select_range 957755
Select_range_check 0
Select_scan 57577013
Slave_heartbeat_period 0.000
Slave_open_temp_tables 0
Slave_received_heartbeats 0
Slave_retried_transactions 0
Slave_running OFF
Slow_launch_threads 0
Slow_queries 445
Sort_merge_passes 3531
Sort_range 5655320
Sort_rows 43857009
Sort_scan 757681
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 51310065
Variable_name Value
Table_locks_waited 14101
Tc_log_max_pages_used 0
Tc_log_page_size 0
Tc_log_page_waits 0
Threads_cached 0
Threads_connected 4
Threads_created 26787751
Threads_running 1
Uptime 1208447
Uptime_since_flush_status 1208447
当前显示的全球变量：
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 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 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
event_scheduler OFF
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 3
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 YES
hostname silldb5
ignore_builtin_innodb OFF
init_connect
init_file
init_slave
innodb_adaptive_flushing ON
innodb_adaptive_hash_index ON
innodb_additional_mem_pool_size 8388608
innodb_autoextend_increment 8
innodb_autoinc_lock_mode 1
innodb_buffer_pool_instances 1
innodb_buffer_pool_size 134217728
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 OFF
innodb_flush_log_at_trx_commit 1
innodb_flush_method
innodb_force_load_corrupted OFF
innodb_force_recovery 0
innodb_io_capacity 200
innodb_large_prefix OFF
innodb_lock_wait_timeout 50
innodb_locks_unsafe_for_binlog OFF
innodb_log_buffer_size 8388608
innodb_log_file_size 5242880
innodb_log_files_in_group 2
innodb_log_group_home_dir ./
Variable_name Value
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_purge_batch_size 20
innodb_purge_threads 0
innodb_random_read_ahead OFF
innodb_read_ahead_threshold 56
innodb_read_io_threads 4
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 1.1.8
innodb_write_io_threads 4
interactive_timeout 28800
join_buffer_size 131072
keep_files_on_create OFF
key_buffer_size 16384
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
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 OFF
log_bin_trust_function_creators OFF
log_error /var/lib/mysql/db.err
log_output FILE
log_queries_not_using_indexes OFF
log_slave_updates OFF
log_slow_queries OFF
log_warnings 1
long_query_time 10.000000
low_priority_updates OFF
lower_case_file_system OFF
lower_case_table_names 0
max_allowed_packet 1048576
max_binlog_cache_size 18446744073709547520
max_binlog_size 1073741824
max_binlog_stmt_cache_size 18446744073709547520
max_connect_errors 10
max_connections 2000
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 1048576
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 2048
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 10000
optimizer_prune_level 1
Variable_name Value
optimizer_search_depth 62
optimizer_switch index_merge=on,index_merge_union=on,index_merge_so...
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
query_alloc_block_size 8192
query_cache_limit 1048576
query_cache_min_res_unit 4096
query_cache_size 8 388 608
query_cache_type ON
query_cache_wlock_invalidate OFF
query_prealloc_size 8192
range_alloc_block_size 4096
read_buffer_size 262144
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 1
skip_external_locking ON
skip_name_resolve ON
skip_networking OFF
skip_show_database OFF
slave_compressed_protocol OFF
slave_exec_mode STRICT
slave_load_tmpdir /tmp
slave_net_timeout 3600
slave_skip_errors OFF
slave_transaction_retries 10
slave_type_conversions
slow_launch_time 2
slow_query_log OFF
slow_query_log_file /var/lib/mysql/slow.log
socket /var/lib/mysql/mysql.sock
sort_buffer_size 65536
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
sync_binlog 0
sync_frm ON
sync_master_info 0
sync_relay_log 0
sync_relay_log_info 0
system_time_zone CET
table_definition_cache 400
table_open_cache 4
thread_cache_size 100
thread_concurrency 8
thread_handling one-thread-per-connection
thread_stack 524288
time_format %H:%i:%s
Variable_name Value
time_zone SYSTEM
timed_mutexes OFF
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 5.5.20
version_comment MySQL Community Server (GPL) by Remi
version_compile_machine x86_64
version_compile_os Linux
wait_timeout 28800
答案 0 :(得分：23)
优化mysql在网上得到很好的评论，你会发现有关如何执行此操作的大量信息。永远不会有“最佳参数”，最好的参数是符合您需求的，盒子硬件，mysql用法...... 所以，我不会给出最好的参数，而是如何定义这些参数。做一些测试，你会很快找到自己的参数。
有很多可用的参数，但只有少数对于调整你的mysql框非常重要。
最重要的变量是（对我而言，并非详尽无遗）：
- max_connections
- wait_timeout
- thread_cache_size
- table_cache
- key_buffer_size
- query_cache_size
- tmp_table_size
要获取已加载的mysql服务器的统计信息，请运行上面提到的mysqladmin processlist extended-status。
1 - 两个最重要的变量： Table_cache和Key_buffer_size
这是第一个严重的问题。 ＆＃34; table_cache是打开的数量 所有线程的表。 MySQL是多线程的，可能运行很多 桌面上的查询一次，每个都会打开一个表格。＆＃34; 因此，即使我们只有几张桌子，我们还需要更多 open_tables。
Opened_tables值为高并显示数量 缓存未命中。获得table_cache大小是正确的两个之一 你可以做些什么来提高绩效。
“key_buffer_size会影响索引缓冲区的大小和速度 索引处理，特别是阅读。＆＃34; MySQL手册（和其他来源）说 ＆＃34; Key_reads / Key_read_request比率通常应<＆lt; 0.01＆＃34。这是 其他最重要的事情要弄清楚。这里的值似乎是正确的（<0.01）
同时检查key_write_requests和key_writes。 key_writes / key_writes_request通常应该是＆lt; 1（近0.5似乎没问题）
这是一个非常有趣的网络指针：table_cache and key_buffer_size
2 - 其他重要设置包括： Wait_timeout，max_connexion，thread_cache
一点解释： 通常你有很多正在睡眠的mysql进程，因为wait_timeout没有设置为低。所以我确保wait_timeout设置为一个非常低的值：15秒（对我而言）。这意味着MySQL将关闭任何空闲超过15秒的连接。
问题是你还必须增加你的max_connexion（我的设置为300）以确保没有很多空闲客户端持有连接并阻止新客户端连接并完成实际工作。 pbm是盒子必须以非常高的速率创建新线程（MySQL是一个多线程服务器）。这可能会占用可测量的CPU时间。
所以解决方案是使用Thread_cache（来自mysql doc）： “我们应该在缓存中保留多少个线程以供重用。当客户端断开连接时，如果之前没有多个thread_cache_size线程，则将客户端的线程放入缓存中。所有新线程首先从缓存中获取，并且仅当缓存为空时才创建新线程。如果您有许多新连接，可以增加此变量以提高性能。 （通常情况下，如果你有一个好的线程实现，这并没有显着提高性能。）通过检查Connections和Threads_created之间的区别，你可以看到当前线程缓存对你有多高效。“
这是应该修复的第二个问题。缓存大小为零是my-medium.cnf的默认值，但my-large.cnf中的建议大小为8。
您可以尝试以下公式：table_cache = opened table / max_used_connection
3 - 最后，您还可以查看： tmp_table_size和Handler_read_rnd / Handler_read_rnd_next
tmp_table_size 32M Created_tmp_disk_tables 3227 Created_tmp_tables 159832 Created_tmp_files 4444
Created_tmp_disk_tables是＆＃34;隐含临时表的数量 执行语句时创建的磁盘＆＃34;和Created_tmp_tables是 基于记忆。显然，如果你不得不去磁盘，这是不好的 记忆。大约2％的临时表进入磁盘，这看起来并不太糟糕 但是增加tmp_table_size可能也不会造成伤害。
这些价值很高，我们可能会有所改善 索引和查询。
我希望这有助于你们中的一些人更好地了解如何优化MYSQL以满足您的需求，硬件盒或mysql当前使用。
答案 1 :(得分：1)
对于那些稍后会阅读此回复的人：
仅适用于少于6.0的MYSQL服务器如果您更改tmp_table_size，请不要忘记带有max_heap_table_size值。
解释here
关于此VARS的另一个主题：here
答案 2 :(得分：-1)
对于刚刚发现这篇非常有用的帖子的人来说，其他可能的变化包括：
由于max_used_connections为137，因此可以安全地减少2000的max_connections。
16384字节的key_buffer_size对于工作负载来说似乎非常小。
key_cache_division_limit = 50会在热/暖内存中保留重复使用的密钥，并避免磁盘读取。
key_age_threshold = 3600秒会使内存中的密钥保持1小时而不是5分钟。
open_files_limit = 1024将支持工作量。