为什么这个查询需要这么长时间？
[英]Why does this query take so long?
问题描述
I have a complex query I need to run on a MySQL-server. 
我有一个复杂的查询，我需要在MySQL服务器上运行。
On my home testing box, a mac, the query takes a reported 0.00 seconds and returns the reslut instantly. 在我的家庭测试盒，一个mac，查询报告0.00秒并立即返回reslut。
On my server however, an ubuntu box, the same query takes around 3.30 minutes, using the same data. 然而，在我的服务器上，一个ubuntu框，相同的查询大约需要3.30分钟，使用相同的数据。
The database uses InnoDB tables. 该数据库使用InnoDB表。 The ubuntu box has a 64-bit kernel, and mysql is compiled for this. ubuntu框有一个64位内核，为此编译mysql。
Why does the ubuntu server take so much longer time to execute the query? 为什么ubuntu服务器需要这么长的时间来执行查询？
These are the configuration variables from the ubuntu-box: 这些是ubuntu-box中的配置变量：
mysql> show variables;
+---------------------------------+-----------------------------+
| Variable_name | Value |
+---------------------------------+-----------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr/ |
| binlog_cache_size | 32768 |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | utf8 |
| 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 | utf8_danish_ci |
| collation_server | latin1_swedish_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 |
| keep_files_on_create | OFF |
| engine_condition_pushdown | OFF |
| expire_logs_days | 10 |
| flush | OFF |
| flush_time | 0 |
| ft_boolean_syntax | + -><()~*:""&| |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| group_concat_max_len | 1024 |
| have_archive | YES |
| have_bdb | NO |
| have_blackhole_engine | YES |
| have_compress | YES |
| have_crypt | YES |
| have_csv | YES |
| have_dynamic_loading | YES |
| have_example_engine | NO |
| have_federated_engine | DISABLED |
| have_geometry | YES |
| have_innodb | YES |
| have_isam | NO |
| have_merge_engine | YES |
| have_ndbcluster | DISABLED |
| have_openssl | DISABLED |
| have_ssl | DISABLED |
| have_query_cache | YES |
| have_raid | NO |
| have_rtree_keys | YES |
| have_symlink | YES |
| hostname | databaseserver |
| init_connect | |
| init_file | |
| init_slave | |
| innodb_additional_mem_pool_size | 8388608 |
| innodb_autoextend_increment | 8 |
| innodb_buffer_pool_awe_mem_mb | 0 |
| innodb_buffer_pool_size | 1073741824 |
| innodb_checksums | ON |
| innodb_commit_concurrency | 0 |
| innodb_concurrency_tickets | 500 |
| innodb_data_file_path | ibdata1:10M:autoextend |
| innodb_data_home_dir | |
| innodb_adaptive_hash_index | ON |
| innodb_doublewrite | ON |
| innodb_fast_shutdown | 1 |
| innodb_file_io_threads | 4 |
| innodb_file_per_table | OFF |
| innodb_flush_log_at_trx_commit | 2 |
| innodb_flush_method | O_DIRECT |
| innodb_force_recovery | 0 |
| innodb_lock_wait_timeout | 50 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_arch_dir | |
| innodb_log_archive | OFF |
| innodb_log_buffer_size | 4194304 |
| innodb_log_file_size | 5242880 |
| innodb_log_files_in_group | 2 |
| innodb_log_group_home_dir | ./ |
| innodb_max_dirty_pages_pct | 90 |
| innodb_max_purge_lag | 0 |
| innodb_mirrored_log_groups | 1 |
| innodb_open_files | 300 |
| innodb_rollback_on_timeout | OFF |
| innodb_support_xa | ON |
| innodb_sync_spin_loops | 20 |
| innodb_table_locks | ON |
| innodb_thread_concurrency | 8 |
| innodb_thread_sleep_delay | 10000 |
| interactive_timeout | 28800 |
| join_buffer_size | 131072 |
| key_buffer_size | 16777216 |
| 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 |
| lc_time_names | en_US |
| license | GPL |
| local_infile | ON |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | OFF |
| log_bin_trust_function_creators | OFF |
| log_error | |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_queries | ON |
| log_warnings | 1 |
| long_query_time | 1 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 16777216 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 104857600 |
| max_connect_errors | 10 |
| max_connections | 100 |
| 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_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 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 9223372036853727232 |
| myisam_recover_options | BACKUP |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 8388608 |
| myisam_stats_method | nulls_unequal |
| ndb_autoincrement_prefetch_sz | 1 |
| ndb_force_send | ON |
| ndb_use_exact_count | ON |
| ndb_use_transactions | ON |
| ndb_cache_check_time | 0 |
| ndb_connectstring | |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old_passwords | OFF |
| open_files_limit | 1024 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| pid_file | /var/run/mysqld/mysqld.pid |
| plugin_dir | |
| 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 | 16777216 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| 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.info |
| relay_log_purge | ON |
| relay_log_space_limit | 0 |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| secure_file_priv | |
| server_id | 0 |
| skip_external_locking | ON |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_load_tmpdir | /tmp/ |
| slave_net_timeout | 3600 |
| slave_skip_errors | OFF |
| slave_transaction_retries | 10 |
| slow_launch_time | 2 |
| socket | /var/run/mysqld/mysqld.sock |
| sort_buffer_size | 2097144 |
| sql_big_selects | ON |
| sql_mode | |
| sql_notes | ON |
| 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_cache | 64 |
| table_lock_wait_timeout | 50 |
| table_type | MyISAM |
| thread_cache_size | 8 |
| thread_stack | 131072 |
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| tmp_table_size | 33554432 |
| tmpdir | /tmp |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| updatable_views_with_limit | YES |
| version | 5.0.75-0ubuntu10.5-log |
| version_comment | (Ubuntu) |
| version_compile_machine | x86_64 |
| version_compile_os | debian-linux-gnu |
| wait_timeout | 28800 |
+---------------------------------+-----------------------------+
This is the query: 这是查询：
SELECT work.id work \
, count( DISTINCT( u.id ) ) number_of_editions \
, GROUP_CONCAT( DISTINCT( u.main_title ) ) main_title \
, GROUP_CONCAT( DISTINCT( main_author.full_name ) ) main_author \
, CONCAT_WS(' ', \
GROUP_CONCAT( DISTINCT( u.sub_title_1 ) ) \
,GROUP_CONCAT( DISTINCT( u.sub_title_2 ) ) \
,GROUP_CONCAT( DISTINCT( u.sub_title_3 ) ) \
,GROUP_CONCAT( DISTINCT( u.sub_title_4 ) ) \
,GROUP_CONCAT( DISTINCT( u.sub_title_5 ) ) \
,GROUP_CONCAT( DISTINCT( u.alternative_title ) ) \
,GROUP_CONCAT( DISTINCT( sst.title ) ) \
) boktitler \
, GROUP_CONCAT( DISTINCT( a.full_name ) ) authorname \
, GROUP_CONCAT( DISTINCT( lp.name )) literary_award \
, GROUP_CONCAT( DISTINCT( f.name )) publisher \
, GROUP_CONCAT( DISTINCT( st.title )) series \
, GROUP_CONCAT( DISTINCT( otn.time )) about_period \
, GROUP_CONCAT( DISTINCT( ostn.place )) about_place \
, GROUP_CONCAT( DISTINCT( opn.full_name )) about_person \
, GROUP_CONCAT( DISTINCT( eon.tag )) utag \
, GROUP_CONCAT( DISTINCT( pt.title )) parallell_title \
, work.owners number_of_owners \
FROM core_work work \
LEFT \
JOIN core_edition u \
ON u.work_id = work.id \
LEFT \
JOIN core_author main_author \
ON main_author.edition_id = u.id AND main_author.nr = 1 \
LEFT \
JOIN core_conjoined_title sst \
ON sst.edition_id = u.id \
LEFT \
JOIN core_parallell_title pt \
ON pt.edition_id = u.id \
LEFT \
JOIN core_editiontag eo \
ON eo.edition_id = u.id \
LEFT \
JOIN core_utag eon \
ON eon.id = eo.tag_id \
LEFT \
JOIN core_edition_about_persons op \
ON op.edition_id = u.id \
LEFT \
JOIN core_about_person opn \
ON opn.id = op.about_person_id \
LEFT \
JOIN core_edition_about_place ost \
ON ost.edition_id = u.id \
LEFT \
JOIN core_about_place ostn \
ON ostn.id = ost.about_place_id \
LEFT \
JOIN core_edition_abouttime ot \
ON ot.edition_id = u.id \
LEFT \
JOIN core_abouttime otn \
ON otn.id = ot.abouttime_id \
LEFT \
JOIN core_seriesnr vs \
ON vs.edition_id = u.id \
LEFT \
JOIN core_series st \
ON st.id = vs.series_id \
LEFT \
JOIN core_edition_publisher uf \
ON uf.edition_id = u.id \
LEFT \
JOIN core_publisher f \
ON f.id = uf.publisher_id \
LEFT \
JOIN core_author a \
ON a.edition_id = u.id AND a.nr > 1 \
LEFT \
JOIN core_awarded_literary_award tlp \
ON tlp.edition_id = u.id \
LEFT \
JOIN core_literary_award lp \
ON tlp.literary_award_id = lp.id \
LEFT \
JOIN core_source source \
ON u.source_id = source.id \
WHERE u.hidden = 0 \
AND number_of_editions > 0 \
GROUP \
BY work.id \
LIMIT 1;
The data in the two databases should be identical (I dumped to file from one and restored to the other). 两个数据库中的数据应该相同（我从一个转储到文件并恢复到另一个）。 When I do EXPLAIN SELECT, there is a difference between the answers: (Identical rows edited out) 当我执行EXPLAIN SELECT时，答案之间存在差异:(编辑相同的行）
Fast testing machine: 快速试验机：
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+------+-------------+
| 1 | SIMPLE | work | index | PRIMARY,work_number_of_editions | PRIMARY | 4 | NULL | 2 | Using where |
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+------+-------------+
Slow machine: 慢机器：
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+--------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+--------+-----------------------------+
| 1 | SIMPLE | work | range | PRIMARY,work_number_of_editions | work_number_of_editions | 5 | NULL | 106796 | Using where; Using filesort |
+----+-------------+-------------+--------+---------------------------------------+---------------------------------------+---------+-----------------------------------+--------+-----------------------------+
This puzzles me; 这让我很困惑; why does the ubuntu server report 106796 rows when it has the same data as the other? 为什么ubuntu服务器报告106796行时，它们具有与另一个相同的数据？ And why does the slow machine use filesort? 为什么慢机器使用filesort？
2 个解决方案
解决方案1
1 2010-09-13 13:41:06
Try to use EXPLAIN SELECT ... on both servers. 尝试在两台服务器上使用EXPLAIN SELECT ... That will show which indexes are being used and how. 这将显示正在使用哪些索引以及如何使用。 If there's any differences in the setup on both machines, it should affect the query plan (eg some table is missing an index on your server). 如果两台计算机上的设置存在任何差异，则应该影响查询计划（例如，某些表缺少服务器上的索引）。
Are the data sets on both machines the same? 两台机器上的数据集是否相同？ If you only have a small subset of the data on your home machine, and the full "larger" dataset on the server, that would also affect things. 如果您的家庭计算机上只有一小部分数据，并且服务器上有完整的“更大”数据集，那么这也会影响事情。 You're using a lot of DISTINCT modifiers and GROUP_CONCATS and joining a large number of tables. 您正在使用大量 DISTINCT修饰符和GROUP_CONCATS并加入大量表。 This could require the use of a fair number of temporary tables and you may be exceeding the available memory, forcing MySQL to use disk buffering, which is very slow compared to in-memory operations. 这可能需要使用相当数量的临时表，并且您可能超出可用内存，迫使MySQL使用磁盘缓冲，这与内存操作相比非常慢。
解决方案2
0 2010-09-13 10:36:17
尝试OPTIMIZE和ANALYZE所有表
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.
相关问题
为什么插入查询偶尔需要很长时间才能完成？ - Why does an insert query occasionally take so long to complete?
当我的 SELECT 查询不需要时，为什么我的 UPDATE 查询需要这么长时间？ - Why does my UPDATE query take so long when my SELECT query doesn't?
为什么这个MySQL查询即使有索引也要花这么长时间进行排序？ - Why does this MySQL query take so long for sorting even though it has an index?
为什么这个简单的MySQL更新查询需要这么长时间？ - Why would this simple MySQL update query take so long?
存在查询需要很长时间 - query with exist take so long
为什么使用MySQL连接进行DNS查找需要这么长时间？ - Why does a DNS lookup take so long with a MySQL connection?
为什么我的桌子需要这么长时间才能加载 - Why does my table take so long to load
为什么添加 AUTO_INCREMENT 需要这么长时间？ - Why does adding AUTO_INCREMENT take so long?
为什么填充我的桌子需要这么长时间？ - Why does populating my table take so long?
为什么要花这么长时间重命名mysql中的列？ - Why does it take so long to rename a column in mysql?
相关标签