Lost Connection To Mysql Server During Query

[smine]

hi. i have a query with 5 UNIONs (6 SELECTs). it runs fine unless i add ORDER BY and then it fails with “Lost connection to MySQL server during query”. it is reproducible.

if i run the same query from MySQL commandline, it works fine.

i played around with it a little bit and there seems to be somehow dependent on the number of UNIONs and the number of JOINs in each SELECT. i don't have a complete explanation, hopefully you can figure it out. 🙂

thanks!

SQLyog v9.32 GA, Windows XP 2002 SP3, 3GB RAM.

[smine]

ah, i just found something! if i turn off the Profiler, i don't get the error.

[ashwin]

Hello,

Can you please tell your MySQL server version(SELECT VERSION())? If you are using server version less than 5.1.49 then you will be hitting this server bug: http://bugs.mysql.com/bug.php?id=52711

This is the bug fix in server 5.1.49:

– Security Fix: Using EXPLAIN with queries of the form SELECT … UNION … ORDER BY (SELECT … WHERE …) could cause a server crash. (Bug #52711, CVE-2010-3682)

Refer: http://dev.mysql.com/doc/refman/5.1/en/news-5-1-49.html

When you executed in command line you did not encounter “Lost Connection To Mysql Server During Query” because EXPLAIN SELECT was not included in the query. If the Profiler is ON and when you run the query, EXPLAIN SELECT is executed.

You can verify this by including EXPLAIN SELECT query in command line 🙂 .

Regards,

Ashwin A

[smine]

ah, yes, thank you. we are running v5.0.45 🙁

[Author]

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