MYSQL巨大的SQL文件插入| MyISAM插入速度突然变慢（奇怪的问题）

Question

我面临一个非常奇怪的问题，我在这里问过有关加快MYSql插入速度的问题尤其是有关插入多个GB大小的巨大SQL文件的问题。他们建议我使用MyISAM引擎。我做了以下事情：

• ALTER TABLE revision ENGINE=MyISAM;
• 使用ALTER TABLE .. DISABLE KEYS。
• （仅限MyISAM）设置bulk_insert_buffer_size为500M。
• （仅限MyISAM）设置unique_checks = 0。没有检查。
• SET autocommit=0; ... SQL import statements ... COMMIT;
• SET foreign_key_checks=0;

它将过程加快到5分钟，之前花费了2个小时，给我留下了深刻的印象。但是现在当我在其他表上尝试相同的操作时，则无法加快速度，并且 又要花费几个小时
：（…

最初获得成功时，我的 CPU使用率约为90％ ，插入仅用了5分钟，但是现在按照相同的程序，我的 CPU使用率 最大 约为5％
。它表明有问题。

我还通过以下方法验证了我的表引擎是MyISAM：

SHOW TABLE STATUS WHERE Name = 'xxx';

注意：我使用的是Wikipedia数据库架构，我
从Wikipedia数据集中获得了Categorylinks表的成功。我在修订版，页面和文本表上没有成功（非常慢的插入速度）。

请帮助我解决这个奇怪的问题。

Answer 1

问题的背后，我还没有找到理想的原因。但是，当我深入研究时，我发现它通常与具有丰富关系的表相比，性能低。尽管我已禁用了这些键。.但是我仍然相信以下设置最适合插入大文件，因为以下设置在多数表上具有最佳性能：

 - ALTER TABLE revision ENGINE=MyISAM;
 - Use ALTER TABLE .. DISABLE KEYS .
 - (MyISAM only) Set bulk_insert_buffer_size to 500M.
 - (MyISAM only) Set unique_checks = 0 . not checked. 
 - SET autocommit=0; ... SQL import
 - statements ... COMMIT;
 - SET foreign_key_checks=0;

有关性能调整的其他调整如下：请参阅完整的my.cnf文件。

#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
# 
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
bulk_insert_buffer_size = 1G
lc-messages-dir = /usr/share/mysql
skip-grant-tables
skip-networking
skip-external-locking
init_connect='SET autocommit=0'
innodb_buffer_pool_size = 1G
innodb_flush_log_at_trx_commit = 0
max_allowed_packet = 500M
table_open_cache = 512
max_connections=100

query_cache_size=32M

table_cache=512

tmp_table_size=64M

thread_cache_size=8

myisam_max_sort_file_size=100G

myisam_sort_buffer_size=256M

key_buffer_size=512M
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address        = 127.0.0.1
#
# * Fine Tuning
#
key_buffer      = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit   = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
general_log=0
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#log_slow_queries   = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size         = 1G
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem



[mysqldump]
quick
quote-names
max_allowed_packet  = 16M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completition

[isamchk]
key_buffer      = 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/

因此，总体上建议使用这些设置，您将获得可观的性能优势。