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From Bryan Pendleton <bpendle...@amberpoint.com>
Subject Re: [jira] Updated: (DERBY-805) Push join predicates into union and other set operations. DERBY-649 implemented scalar (single table) predicate pushdown. Adding join predicate push down could improve performance significantly.
Date Sat, 08 Apr 2006 02:16:20 GMT
Hi Army,

I love reading your documents! Even if 85% of it is too
optimizer-y for me to understand, I learn a lot each time I
read through your work. So thanks!

One particular sentence from your most recent writeup stuck out
for me, as I had missed this in previous discussions about DERBY-805:

    The second thing was the fact that I created indexes on T3 and
    T4 _before_ inserting the data, which (it turns out) leads to
    outdated (if not altogether incorrect) statistics for the indexes.

Are the statistics always incorrect/outdated after inserting lots
of data into a table which has one or more indexes?

Or was there something specific about the way in which you inserted
your data which caused the indexes to have outdated/incorrect statistics?

thanks,

bryan


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