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POSlow simple UPDATE query
 

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    <p>I have problem with strange behaviour of mysql. Simple update query with only primary key in where clause on table with ~3000 rows takes sometimes more than 2 seconds. It gets stuck on "query end" phase with high Context_voluntary value (200+) according to <code>SHOW PROFILE ALL</code> command.</p> <p>In most of the cases, it is the first query in the connection.</p> <p>Sample query:</p> <pre><code>UPDATE `users` set last_portal_login = NOW() , ip = 1464635301 , browser = "chrome" where uid = 2021 </code></pre> <p>Create table query: <code><pre>CREATE TABLE <code>users</code> ( <code>uid</code> int(10) unsigned NOT NULL, <code>login</code> char(50) COLLATE utf8_polish_ci NOT NULL, <code>hide_me</code> tinyint(1) unsigned NOT NULL DEFAULT '0', <code>addon</code> int(10) unsigned NOT NULL DEFAULT '0', <code>protocol</code> float unsigned NOT NULL DEFAULT '0', <code>mode</code> enum('firefox','lite','chrome','opera') COLLATE utf8_polish_ci DEFAULT NULL, <code>browser</code> enum('firefox','chrome','opera','ie','safari') COLLATE utf8_polish_ci DEFAULT NULL, <code>last_login</code> datetime DEFAULT NULL, <code>last_portal_login</code> datetime DEFAULT NULL, <code>ip</code> int(10) unsigned DEFAULT NULL, PRIMARY KEY (<code>uid</code>), UNIQUE KEY <code>login</code> (<code>login</code>) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_polish_ci$$</pre></code></p> <p>Here is the InnoDB configuration: <code><pre>'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: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', '2' 'innodb_flush_method', 'O_DIRECT' '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', '67108864' '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_print_all_deadlocks', 'OFF' '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', '5.5.30' 'innodb_write_io_threads', '4'</pre></code></p> <p>Mysql version: 5.5.30 from dotdeb.org, connection is based on unix socket.</p> <p>What should I do to fix this?</p>
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    1. USrogers
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      1. VTUpMod
    1. COtry utf8_general_ci/ascii maybe for enum or use varchar instead. enum is painful to maintain
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      1. USJuris Malinens
    2. COit doesn't give any improvement, still sometimes query takes more than 2 seconds stuck on "query end". Actually, I think, that changing enum to varchar can slow down everything.
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      1. USrogers
    3. COtransform the UPDATE into a SELECT and see how long it takes, and also post here the result of EXPLAIN on that SELECT
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      1. USgolimar
 

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