大约有 40,000 项符合查询结果（耗时：0.0243秒） [XML]
Favourite performance tuning tricks [closed]
...n-optimal query plan
Break up the Join
Can you break up the join?
Pre-select foreign keys into a temporary table
Do half the join and put results in a temporary table
Are you using the right kind of temporary table?
#temp tables may perform much better than @table variables with large volum...
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
...Shouldn't the threads in the connection pool be kept active by firing the "select 1" validation query? Why would they get closed by prolonged inactivity when we have set the evictor to run at shorter time intervals than the mysql server timeout?
– Farhad
Sep 2 ...
ERROR 2006 (HY000): MySQL server has gone away
...L/MariaDB server.
Double check the value was set properly by:
mysql -sve "SELECT @@max_allowed_packet" # or:
mysql -sve "SHOW VARIABLES LIKE 'max_allowed_packet'"
You got a timeout from the TCP/IP connection on the client side.
Solution: Increase wait_timeout variable.
You tried to run a query a...
What is the most ridiculous pessimization you've seen? [closed]
...nearly all their tables have an associated archive table, and most queries select from views that UNION the pairs of tables. Performance is as you would expect!
– Tony Andrews
Mar 26 '09 at 13:32
...
Get the week start date and week end date from week number
...y other weird value to test it */
DECLARE @d DATETIME
SET @d = GETDATE()
SELECT
@d ThatDate,
DATEADD(dd, 0 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Monday,
DATEADD(dd, 6 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Sunday
...
实战低成本服务器搭建千万级数据采集系统 - 更多技术 - 清泛网 - 专注C/C++...
...oncrawler上一篇文章《社会化海量数据采集框架搭建》提到如何搭建一个社会化采集系统架构，讲架构一般都比较虚，这一篇讲一下如何实战用低成本服务器...有这样一个采集系统的需求，达成指标： 需要采集30万关键词的数据 ...
淘宝大秒系统设计详解 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...进行动静分离，这也是解决大流量系统的一个重要原则。如何给系统做动静分离的静态化改造我以前写过一篇《高访问量系统的静态化架构设计》详细介绍了淘宝商品系统的静态化设计思路，感兴趣的可以在《程序员》杂志上找...
error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' — Miss
...ate to where your mysql.sock file is located
Right click on the file and select Make Link
Rename the Link File to mysqld.sock then Right click on the file and Cut it
Go to /var/run and create a folder called mysqld and enter it
Now right click and Paste the Link File
Voila! You will now have a mys...
Sql Server string to date conversion
...what you're looking for. It wont be hard to adapt:
Declare @d datetime
select @d = getdate()
select @d as OriginalDate,
convert(varchar,@d,100) as ConvertedDate,
100 as FormatValue,
'mon dd yyyy hh:miAM (or PM)' as OutputFormat
union all
select @d,convert(varchar,@d,101),101,'mm/dd/yy'
union al...
Force drop mysql bypassing foreign key constraint
...
If you are using phpmyadmin then this feature is already there.
Select the tables you want to drop
From the dropdown at the bottom of tables list, select drop
A new page will be opened having checkbox at the bottom saying
"Foreign key check", uncheck it.
Confirm the deletion by accepting ...