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Post #284,827
by drewk
Picture of drewk
5/16/07 11:07:16 PM
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New What I'd do
Start at the half-month criteria. Increase one day at a time until the performance tanks. Then (assuming you've been keeping the start date and moving the end date closer to NOW) back up both the start and end dates. See if it's the number of days, or that specific day that's causing problems.
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Kip Hawley is still an idiot.

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Purveyor of Doc Hope's [link|http://DocHope.com|fresh-baked dog biscuits and pet treats].
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Post #284,830
by static
5/17/07 12:09:44 AM
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New I approached that from another direction.
The original query, actually generated by code I wrote being invoked by an end-user, was for a whole month. I fished the query out of the debugging.

I already knew a smaller time-frame affects this query. So I doubted it was data-based. But I did the sort of test you described: I ran it for the first half of the month: 7 seconds. Then I altered the dates for the second half of the month: 7 seconds. :-/ It's obviously the number of days. I can find the break point without too much more effort, but I don't think knowing that will win me anything.

Wade.

Is it enough to love
Is it enough to breathe
Somebody rip my heart out
And leave me here to bleed
 
Is it enough to die
Somebody save my life
I'd rather be Anything but Ordinary
Please



-- "Anything but Ordinary" by Avril Lavigne.

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Post #284,834
by dws
5/17/07 1:41:19 AM
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New Re: I approached that from another direction.
EXPLAIN is your friend in weird cases like this. If you find that MySQL, for reasons obscure, has decided to do a full table scan, you can use a FORCE INDEX hint to set things right (for MySQL 5.0+, at least).

[link|http://dev.mysql.com/doc/refman/5.0/en/index-hints.html|http://dev.mysql.com.../index-hints.html] for details.
Post #284,847
by static
5/17/07 8:40:14 AM
Reply
New FORCE INDEX is new to me.
I had been using EXPLAIN. And USE INDEX. With it without USE INDEX, a month or half-a-month, it still uses the correct index. I'll try FORCE INDEX, though.

Wade.

Is it enough to love
Is it enough to breathe
Somebody rip my heart out
And leave me here to bleed
 
Is it enough to die
Somebody save my life
I'd rather be Anything but Ordinary
Please



-- "Anything but Ordinary" by Avril Lavigne.

· my ·
· [link|http://staticsan.livejournal.com/|blog] ·
· [link|http://yceran.org/|website] ·
     After some MySQL clues. - (static) - (4) - May 16, 2007, 09:14:39 PM EDT
         What I'd do - (drewk) - (3) - May 16, 2007, 11:07:16 PM EDT
             I approached that from another direction. - (static) - (2) - May 17, 2007, 12:09:44 AM EDT
                 Re: I approached that from another direction. - (dws) - (1) - May 17, 2007, 01:41:19 AM EDT
                     FORCE INDEX is new to me. - (static) - May 17, 2007, 08:40:14 AM EDT

I am the Walrus.
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