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From Matt Doran <matt.do...@papercut.com>
Subject Re: FW: Advice on *very* badly performing query
Date Thu, 06 Dec 2007 00:15:52 GMT
Hi Kim,

Kim Haase wrote:
> Do you think it might also help to put the information into the Tuning 
> Guide under "Performance tips and tricks"?
>
> http://db.apache.org/derby/docs/dev/tuning/tuning-single.html#ctunperf22457 
>
Yeah, I think something more prominent in there would be a good place to 
start.  There is a mention of this further down in the "Working with 
cardinality statistics" section, however a statement about this should 
probably go up in the performance tips.


I think one of the major problems with the way derby generates the 
stats, is that it will only generate stats if the index is created on a 
"non-empty" table.  I'd say that 99% of the time, indexes are created 
before the data added to the tables.  So the stats never get created.    

Making this very clear in the performance tips, would be a great step 
forward.

Thanks,
Matt

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