如何查询MySql日志

今天美国老板发来一封email，一句What happen to ...? 其他任何线索没有，我的给出答案，一一排查，看能否找到问题缘由或是恢复数据，更新问题？程序问题？结果都是没有头绪，最后想了下mysql的日志看能否看看，以前没看过mysql的日志，查查资料，最终皇天不负有心人，搞定了，现在总结下：

1.首先确认你日志是否启用了

MySQL>show variables like 'log_bin';

2.如果启用了，即ON那日志文件就在MySQL的安装目录的data目录下

3.怎样知道当前的日志

MySQL> show master status;

4.看二进制日志文件用MySQLbinlog

shell>MySQLbinlog mail-bin.000001

或者

shell>MySQLbinlog mail-bin.000001 | tail
因为mail-bin.000001是二进制的日志，所以想看日志就需要用mysqlbinlog命令，将二进制文件转换为日志文件，下面详细说说如何使用：上面已经说过如果启用了日志文件，那么默认的日志文件就在data目录下（如果你没有更改的话）进入存放日志文件目录，使用mysqlbinlog localhost-bin.000202 > new_file_name.log
命令，将目标文件保存为日志文件，可指定保存路径下
有个小技巧跟大家介绍下，我在准备转换的时候发现日志文件有2G多，寻思着为什么mysql为什么不把日志按日志定期的分多个文件放呢。结果发现mysql有个更好的方法，可以通过时间参数获取某个时间段的数据，例子如下：mysqlbinlog    --start-datetime="2010-11-20 00:00:00"  --stop-datetime="2010-11-21 00:00:00"
[hx@localhost data]$ mysqlbinlog
mysqlbinlog Ver 3.0 for pc-linux-gnu at i686
By Monty and Sasha, for your professional use
This software comes with NO WARRANTY: This is free software,
and you are welcome to modify and redistribute it under the GPL licenseDumps a MySQL binary log in a format usable for viewing or for piping to
the mysql command line clientUsage: mysqlbinlog [options] log-files
-d, --database=name List entries for just this database (local log only).
-D, --disable-log-bin
Disable binary log. This is useful, if you enabled
--to-last-log and are sending the output to the same
MySQL server. This way you could avoid an endless loop.
You would also like to use it when restoring after a
crash to avoid duplication of the statements you already
have. NOTE: you will need a SUPER privilege to use this
option.
-f, --force-read    Force reading unknown binlog events.
-?, --help          Display this help and exit.
-h, --host=name     Get the binlog from server.
-o, --offset=#      Skip the first N entries.
-p, --password[=name]
Password to connect to remote server.
-P, --port=#        Use port to connect to the remote server.
-j, --position=#    Deprecated. Use --start-position instead.
--protocol=name     The protocol of connection (tcp,socket,pipe,memory).
-r, --result-file=name
Direct output to a given file.
-R, --read-from-remote-server
Read binary logs from a MySQL server
--open_files_limit=#
Used to reserve file descriptors for usage by this
program
-s, --short-form    Just show the queries, no extra info.
-S, --socket=name   Socket file to use for connection.
--start-datetime=name
Start reading the binlog at first event having a datetime
equal or posterior to the argument; the argument must be
a date and time in the local time zone, in any format
accepted by the MySQL server for DATETIME and TIMESTAMP
types, for example: 2004-12-25 11:25:56 (you should
probably use quotes for your shell to set it properly).
--stop-datetime=name
Stop reading the binlog at first event having a datetime
equal or posterior to the argument; the argument must be
a date and time in the local time zone, in any format
accepted by the MySQL server for DATETIME and TIMESTAMP
types, for example: 2004-12-25 11:25:56 (you should
probably use quotes for your shell to set it properly).
--start-position=# Start reading the binlog at position N. Applies to the
first binlog passed on the command line.
--stop-position=#   Stop reading the binlog at position N. Applies to the
last binlog passed on the command line.
-t, --to-last-log   Requires -R. Will not stop at the end of the requested
binlog but rather continue printing until the end of the
last binlog of the MySQL server. If you send the output
to the same MySQL server, that may lead to an endless
loop.
-u, --user=name     Connect to the remote server as username.
-l, --local-load=name
Prepare local temporary files for LOAD DATA INFILE in the
specified directory.
-V, --version       Print version and exit.Variables (--variable-name=value)
and boolean options {FALSE|TRUE} Value (after reading options)
--------------------------------- -----------------------------
database                          (No default value)
disable-log-bin                   FALSE
force-read                        FALSE
host                              (No default value)
offset                            0
port                              3306
position                          4
read-from-remote-server           FALSE
open_files_limit                  64
short-form                        FALSE
socket                            (No default value)
start-datetime                    (No default value)
stop-datetime                     (No default value)
start-position                    4
stop-position                     18446744073709551615
to-last-log                       FALSE
user                              (No default value)
local-load                        (No default value)2009.09.30 检查一个应用的问题的时候，发现通过 oracle 的 dblink 连接 mysql 进行更新等操作的时候，mysql 不会把操作的 sql 语句记录到日志文件里，有点点郁闷了