Bug #6760 Request SLEEP() function
Submitted: 23 Nov 2004 1:05 Modified: 12 Aug 2005 4:57
Reporter: Paul DuBois
Status: Closed
Category:Server Severity:S4 (Feature request)
Version:any OS:
Assigned to: Jim Winstead Target Version:
Triage: D5 (Feature request)

[23 Nov 2004 1:05] Paul DuBois 
Description:
In scripts that test temporal things such as whether TIMESTAMP
columns update, it would be helpful to have a function that
implements a delay, so that the script can know that the time
has changed.  One can do this with BENCHMARK(), sort of, but
that's subject to limitations: It's subject to processor speed.
A million-iteration BENCHMARK() call on a fast machine might
now actually execute long enough to allow a second to pass,
whereas on a slow machine it might delay a painfully long time.

A SLEEP(n) SQL function to sleep n seconds therefore would be
a nice diagnostic tool.

How to repeat:
See above.
[23 Nov 2004 1:06] Paul DuBois 
Turning off showstopper flag.
[12 Aug 2005 3:05] Jim Winstead 
i need this to write tests.
[12 Aug 2005 3:57] Bugs System 
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/28205
[12 Aug 2005 4:33] Jim Winstead 
Fixed in 5.0.12.
[12 Aug 2005 4:57] Paul DuBois 
Documented function in "Miscellaneous Functions" section.
Noted in 5.0.12 changelog.
[26 Jan 2007 10:14] ILya Kogan 
The SLEEP function appears to work incorrectly. It suspends for much longer period than
the one I pass as a input parameter. I tested it on localhost queries and in stored
procedures and in both cases I got the following results:

select sleep(0.1);
----- 0.63 sec

select sleep(1);
----- 2.23 sec
etc;

This is especially visible for small values of the input parameter, e.g.

select sleep(0.05) 
----- 0.63 sec
[2 Apr 2007 7:01] Ondra Zizka 
Mysql itself does not measure the time. I guess that additional delay in your case  would
be caused by other element's in the roundtrip, or it was already fixed - works fine for
me:

SELECT SLEEP(5); -- takes 5,0002 s in Query Browser
[2 Apr 2007 8:21] Jim Winstead 
The original version of SLEEP() also had issues on Microsoft Windows, where the timing
could be rather wildly off. This was fixed in 5.0.36 and 5.1.15. See Bug #14094.