Eu tenho vários sites com tabelas de sessão em um servidor da web, que são usados pelos sistemas de estrutura Joomla CMS e Symfony. Com slow_query_log=0.6, as consultas de atualização para as tabelas de sessão aparecem regularmente no log lento.
A definição da tabela de sessão do Joomla é
CREATE TABLE IF NOT EXISTS `jos_session` (
`username` varchar(150) DEFAULT '',
`time` varchar(14) DEFAULT '',
`session_id` varchar(200) NOT NULL DEFAULT '0',
`guest` tinyint(4) DEFAULT '1',
`userid` int(11) DEFAULT '0',
`usertype` varchar(50) DEFAULT '',
`gid` tinyint(3) unsigned NOT NULL DEFAULT '0',
`client_id` tinyint(3) unsigned NOT NULL DEFAULT '0',
`data` longtext,
PRIMARY KEY (`session_id`(64)),
KEY `whosonline` (`guest`,`usertype`),
KEY `userid` (`userid`),
KEY `time` (`time`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
Eu tentei mudar o mecanismo de armazenamento para InnoDB sem efeito, tentei otimizar a tabela e também removi todo o índice, mas o principal. Existem registros nesta tabela com espaço de armazenamento
Data 12,352.0 KiB
Index 144.0 KiB
Total 12,496.0 KiB
Configuração do meu servidor
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_uOFF
binlog_format STATEMENT
binlog_stmt_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/share/
collation_connection utf8_genera
collation_database latin1_swed
collation_server latin1_swed
completion_type NO_CHAIN
concurrent_insert AUTO
connect_timeout 10
datadir /var/lib/my
date_format %Y-%m-%d
datetime_format %Y-%m-%d %H
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 10
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/my
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 nzs2.automa
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 8388608
innodb_autoextend_increment 8
innodb_autoinc_lock_mode 1
innodb_buffer_pool_instances 1
innodb_buffer_pool_size 268435456
innodb_change_buffering all
innodb_checksums ON
innodb_commit_concurrency 0
innodb_concurrency_tickets 500
innodb_data_file_path ibdata1:10M
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
Variable_name Value
innodb_log_file_size 5242880
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_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 OFF
innodb_use_sys_malloc ON
innodb_version 1.1.8
innodb_write_io_threads 4
insert_id 0
interactive_timeout 28800
join_buffer_size 262144
keep_files_on_create OFF
key_buffer_size 268435456
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/
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
log_output FILE
log_queries_not_using_indexes OFF
log_slave_updates OFF
log_slow_queries ON
log_warnings 1
long_query_time 0.6
low_priority_updates OFF
lower_case_file_system OFF
lower_case_table_names 0
max_allowed_packet 16777216
max_binlog_cache_size ###
max_binlog_size 104857600
max_binlog_stmt_cache_size ###
max_connect_errors 10
max_connections 100
max_delayed_threads 20
max_error_count 64
max_heap_table_size 25165824
max_insert_delayed_threads 20
max_join_size ###
max_length_for_sort_data 1024
max_long_data_size 16777216
max_prepared_stmt_count 16382
max_relay_log_size 0
max_seeks_for_key ###
max_sort_length 1024
max_sp_recursion_depth 0
max_tmp_tables 32
max_user_connections 0
max_write_lock_count ###
metadata_locks_cache_size 1024
min_examined_row_limit 0
multi_range_count 256
myisam_data_pointer_size 6
myisam_max_sort_file_size ###
myisam_mmap_size ###
myisam_recover_options BACKUP
myisam_repair_threads 1
myisam_sort_buffer_size 8388608
myisam_stats_method nulls_unequ
myisam_use_mmap OFF
net_buffer_length 16384
net_read_timeout 30
net_retry_count 10
net_write_timeout 60
new OFF
Variable_name Value
old OFF
old_alter_table OFF
old_passwords OFF
open_files_limit 2158
optimizer_prune_level 1
optimizer_search_depth 62
optimizer_switch index_merge
performance_schema OFF
performance_schema_events_waits_h 10000
performance_schema_events_waits_h 10
performance_schema_max_cond_class 80
performance_schema_max_cond_insta 1000
performance_schema_max_file_class 50
performance_schema_max_file_handl 32768
performance_schema_max_file_insta 10000
performance_schema_max_mutex_clas 200
performance_schema_max_mutex_inst 1000000
performance_schema_max_rwlock_cla 30
performance_schema_max_rwlock_ins 1000000
performance_schema_max_table_hand 100000
performance_schema_max_table_inst 50000
performance_schema_max_thread_cla 50
performance_schema_max_thread_ins 1000
pid_file /var/run/my
plugin_dir /usr/lib/my
port 3306
preload_buffer_size 32768
profiling OFF
profiling_history_size 15
protocol_version 10
proxy_user
pseudo_thread_id 401326
query_alloc_block_size 8192
query_cache_limit 1048576
query_cache_min_res_unit 4096
query_cache_size 25165824
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 131072
read_only OFF
read_rnd_buffer_size 262144
relay_log
relay_log_index
relay_log_info_file relay-log.i
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 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 /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 /var/log/my
socket /var/run/my
sort_buffer_size 2097152
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 ###
sql_mode
sql_notes ON
sql_quote_show_create ON
sql_safe_updates OFF
sql_select_limit ###
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
Variable_name Value
sync_master_info 0
sync_relay_log 0
sync_relay_log_info 0
system_time_zone NZDT
table_definition_cache 1024
table_open_cache 1024
thread_cache_size 8
thread_concurrency 10
thread_handling one-thread-
thread_stack 196608
time_format %H:%i:%s
time_zone SYSTEM
timed_mutexes OFF
timestamp 1361481911
tmp_table_size 16777216
tmpdir /tmp
transaction_alloc_block_size 8192
transaction_prealloc_size 4096
tx_isolation REPEATABLE-
unique_checks ON
updatable_views_with_limit YES
version 5.5.29-0ubu
version_comment (Ubuntu)
version_compile_machine x86_64
version_compile_os debian-linu
wait_timeout 28800
warning_count 0
Como posso melhorar a velocidade dessas consultas?
Uma consulta típica é do estilo
UPDATE `jos_session`
SET `time`='1361469848',`userid`='0',`usertype`='',`username`='',
`gid`='0',`guest`='1',`client_id`='0',
`data`='__default|a:8:{s:15:\"session.counter\";i:1;s:19:\"session.timer.start\";i:1361469848;s:18:\"session.timer.last\";i:1361469848;s:17:\"session.timer.now\";i:1361469848;s:24:\"session.client.forwarded\";s:28:\"121.205.249.235, 23.15.14.22\";s:22:\"session.client.browser\";s:69:\"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.1.4322)\";s:8:\"registry\";O:9:\"JRegistry\":3:{s:17:\"_defaultNameSpace\";s:7:\"session\";s:9:\"_registry\";a:2:{s:7:\"session\";a:1:{s:4:\"data\";O:8:\"stdClass\":0:{}}s:11:\"application\";a:1:{s:4:\"data\";O:8:\"stdClass\":1:{s:4:\"lang\";s:5:\"en-GB\";}}}s:7:\"_errors\";a:0:{}}s:4:\"user\";O:5:\"JUser\":19:{s:2:\"id\";i:0;s:4:\"name\";N;s:8:\"username\";N;s:5:\"email\";N;s:8:\"password\";N;s:14:\"password_clear\";s:0:\"\";s:8:\"usertype\";N;s:5:\"block\";N;s:9:\"sendEmail\";i:0;s:3:\"gid\";i:0;s:12:\"registerDate\";N;s:13:\"lastvisitDate\";N;s:10:\"activation\";N;s:6:\"params\";N;s:3:\"aid\";i:0;s:5:\"guest\";i:1;s:7:\"_params\";O:10:\"JParameter\":7:{s:4:\"_raw\";s:0:\"\";s:4:\"_xml\";N;s:9:\"_elements\";a:0:{}s:12:\"_elementPath\";a:1:{i:0;s:69:\"/var/www/www.seleconlight.com/libraries/joomla/html/parameter/element\";}s:17:\"_defaultNameSpace\";s:8:\"_default\";s:9:\"_registry\";a:1:{s:8:\"_default\";a:1:{s:4:\"data\";O:8:\"stdClass\":0:{}}}s:7:\"_errors\";a:0:{}}s:9:\"_errorMsg\";N;s:7:\"_errors\";a:0:{}}}country_cc|N;'
WHERE session_id='k3fuukvh8lrfq244u6ic4it605';
Primeiras coisas Defina query_cache_type=0 e query_cache_size=0 em my.cnf Para sistemas multi-core, o cache criará problemas de contenção.
Perguntas importantes Quanta RAM livre está sendo exibida em seu servidor (use o comando top)? Qual é a instrução específica que está aparecendo no log de consulta lenta?
Se você pretende manter o mecanismo de banco de dados da tabela como InnoDB, recomendo que faça innodb_log_file_size = innodb_buffer_pool_size/2 Isso reduzirá os IOs. Certifique-se de seguir as instruções encontradas aqui: http://dev.mysql.com/doc/refman/5.5/en/innodb-data-log-reconfiguration.html no local que começa com "If you want to change the ".
Se você quiser mantê-la como MyISAM, esta tabela será bloqueada a cada atualização. Altere os varchars e longtext para chars para que seja uma tabela de comprimento fixo (consulte http://dev.mysql.com/doc/refman/5.5/en/myisam-table-formats.html
Change the primary key to use a hash index:
On query cache Long story on query cache; if you have the same select query running over and over then yeah it can help, but there's lots of overhead to have it run. General rule, turn it off, and then turn it on if you need to. (see http://www.mysqlperformanceblog.com/2006/07/27/mysql-query-cache/)
Speeding up UPDATE * Thanks for the slow query log statement. The biggest thing that slows updates is updating the indexes. Since you've tried dropping the indexes the next step is to convert the table to InnoDB Engine. MyISAM is not very good with concurrent updates. If there still is no satisfaction, the next step to see if you cannot partition the table across different devices, but make sure the extra administrative burden is worth the benefit. Do you have any extra hard disk devices available to the server not being used?
Joomla session table Upon investigation, this table gets deletes which means it will have holes. If you still want to stick with MyISAM, try setting concurrent_insert=2. You can do this without requiring a maintenance window. (more info: http://dev.mysql.com/doc/refman/5.5/en/concurrent-inserts.html). INSERTS get higher priority over updates so speeding those up may speed up your UPDATE statement.
Memory and InnoDB If you can set the innodb_buffer_pool_size to the total size of the database + indexes of all of the InnoDB tables, then updates will happen in RAM first instead of disk. This is the ideal for perormance. Since I see you are using around 2.7GB on the server, there's probably other apps contending for disk--all the more to go to innodb with the innodb buffer settings.