本帖最后由 dz215136304 于 2013-08-15 11:33:52 编辑
linux下 mysql 300万数据查询500多秒怎么优化啊，其中pid已经做索引,id是主键
SELECT id,pid,keyWords,shortUrl FROM keywords WHERE pid=0 ORDER BY id DESC LIMIT 50
explain 如下：
<br />
<br />
mysql> explain SELECT id,pid,keyWords,shortUrl FROM keywords WHERE pid=0 ORDER BY id DESC LIMIT 50;<br />
+----+-------------+----------+------+---------------+------+---------+-------+---------+-----------------------------+<br />
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |<br />
+----+-------------+----------+------+---------------+------+---------+-------+---------+-----------------------------+<br />
| 1 | SIMPLE | keywords | ref | pid | pid | 4 | const | 2452523 | Using where; Using filesort |<br />
+----+-------------+----------+------+---------------+------+---------+-------+---------+-----------------------------+<br />
1 row in set (8.18 sec)<br />
<br />
另外mysql cpu占用很高怎么回事？内存:512M
配置文件如下：
<br>
# Example MySQL config file for small systems.<br>
#<br>
# This is for a system with little memory (
# from time to time and it's important that the mysqld daemon<br>
# doesn't use much resources.<br>
#<br>
# You can copy this file to<br>
# /etc/my.cnf to set global options,<br>
# mysql-data-dir/my.cnf to set server-specific options (in this<br>
# installation this directory is /usr/local/mysql/var) or<br>
# ~/.my.cnf to set user-specific options.<br>
#<br>
# In this file, you can use all long options that a program supports.<br>
# If you want to know which options a program supports, run the program<br>
# with the "--help" option.<br>
<br>
# The following options will be passed to all MySQL clients<br>
[client]<br>
#password = your_password<br>
port = 3306<br>
socket = /tmp/mysql.sock<br>
<br>
# Here follows entries for some specific programs<br>
<br>
# The MySQL server<br>
[mysqld]<br>
port = 3306<br>
socket = /tmp/mysql.sock<br>
skip-locking<br>
key_buffer = 16K<br>
max_allowed_packet = 1M<br>
table_cache = 4<br>
sort_buffer_size = 64K<br>
read_buffer_size = 256K<br>
read_rnd_buffer_size = 256K<br>
net_buffer_length = 2K<br>
thread_stack = 64K<br>
datadir=/www/mysql/data<br>
log-slow-queries=/www/log/mysql/slowquery.log<br>
long_query_time=2<br>
<br>
<br>
# Don't listen on a TCP/IP port at all. This can be a security enhancement,<br>
# if all processes that need to connect to mysqld run on the same host.<br>
# All interaction with mysqld must be made via Unix sockets or named pipes.<br>
# Note that using this option without enabling named pipes on Windows<br>
# (using the "enable-named-pipe" option) will render mysqld useless!<br>
# <br>
#skip-networking<br>
server-id = 1<br>
<br>
# Uncomment the following if you want to log updates<br>
#log-bin=mysql-bin<br>
<br>
# Uncomment the following if you are NOT using BDB tables<br>
#skip-bdb<br>
<br>
# Uncomment the following if you are using InnoDB tables<br>
#innodb_data_home_dir = /usr/local/mysql/var/<br>
#innodb_data_file_path = ibdata1:10M:autoextend<br>
#innodb_log_group_home_dir = /usr/local/mysql/var/<br>
#innodb_log_arch_dir = /usr/local/mysql/var/<br>
# You can set .._buffer_pool_size up to 50 - 80 %<br>
# of RAM but beware of setting memory usage too high<br>
#innodb_buffer_pool_size = 16M<br>
#innodb_additional_mem_pool_size = 2M<br>
# Set .._log_file_size to 25 % of buffer pool size<br>
#innodb_log_file_size = 5M<br>
#innodb_log_buffer_size = 8M<br>
#innodb_flush_log_at_trx_commit = 1<br>
#innodb_lock_wait_timeout = 50<br>
<br>
[mysqldump]<br>
quick<br>
max_allowed_packet = 16M<br>
<br>
[mysql]<br>
no-auto-rehash <div class="clear">
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