What does /*!40001 SQL_NO_CACHE */ * means

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mister_v
Posts: 188
Joined: Thu Mar 04, 2010 9:19 pm

What does /*!40001 SQL_NO_CACHE */ * means

Post by mister_v »

Hi,

From time to time i check my mysql-slow log:
/var/log/mysql/mysql-slow.log

Last time I saw a query with this:

Code: Select all

SELECT /*!40001 SQL_NO_CACHE */ * FROM db
But I don't have script that runs with this in the query.
where does it come from?
Is some one else accessing my MySQL-server?
chris
Site Admin
Posts: 194
Joined: Mon Jul 21, 2008 9:52 am

Re: What does /*!40001 SQL_NO_CACHE */ * means

Post by chris »

This query is almost certainly due to a mysql dump being run on the database.
Those are the style of queries it submits to extract the data for the dump.

Check for the time when it happens, it might be a backup that is running.

Code: Select all

# Time: 130219 18:11:35
# User@Host: user[host] @ localhost []
# Query_time: 1.807723  Lock_time: 0.000104 Rows_sent: 0  Rows_examined: 4706
SET timestamp=1361293895;
SELECT /*!40001 SQL_NO_CACHE */ * FROM db;
This line Time: 130219 18:11:35
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