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From:Vikas Shukla Date:May 31 2013 2:19am
Subject:RE: Are There Slow Queries that Don't Show in the Slow Query Logs?
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Hi,

No, it does not represents the time from request to response not does
it includes the time that is spent in waiting for the locks to be
released.
The slow query log consists of SQL statements that took more than
long_query_time seconds to EXECUTE. The default value of
long_query_time is 10.
The time to acquire the initial locks is not counted as execution time.
mysqld writes a statement to the slow query log after it has been
executed and after all locks have been released, so log order might
differ from execution order.

Lets take an example, if a query is received at 10:00 hrs and it waits
till 10:05 hrs , it starts getting executed at 10:05:00 and completed
at 10:05:24 (HH:MM:SS). So, here it took 24 seconds to execute. So only
24 seconds is counted.
So if long_query_time is equal to 10, which is by default, this would
be logged in slow query log as it takes more than 10 seconds to execute.

Sent from my Windows Phone From: Robinson, Eric
Sent: 31-05-2013 03:48
To: mysql@stripped
Subject: Are There Slow Queries that Don't Show in the Slow Query Logs?
As everyone knows, with MyISAM, queries and inserts can lock tables
and force other queries to wait in a queue. When that happens, does
the time shown in the slow query logs represent the whole time from
when the server received the request to when the response was sent to
the client? Or is the time a query spends waiting for a table lock to
be released omitted from what is recorded in the slow query logs?

--
Eric Robinson






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Thread
Are There Slow Queries that Don't Show in the Slow Query Logs?Eric Robinson30 May
RE: Are There Slow Queries that Don't Show in the Slow Query Logs?Vikas Shukla31 May
  • RE: Are There Slow Queries that Don't Show in the Slow Query Logs?Eric Robinson31 May