Re: gistchoose vs. bloat
От | Jeff Davis |
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Тема | Re: gistchoose vs. bloat |
Дата | |
Msg-id | 1355508729.11945.26.camel@jdavis обсуждение исходный текст |
Ответ на | Re: gistchoose vs. bloat (Heikki Linnakangas <hlinnakangas@vmware.com>) |
Ответы |
Re: gistchoose vs. bloat
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Список | pgsql-hackers |
On Fri, 2012-12-14 at 18:36 +0200, Heikki Linnakangas wrote: > One question: does the randomization ever help when building a new > index? In the original test case, you repeatedly delete and insert > tuples, and I can see how the index can get bloated in that case. But I > don't see how bloat would occur when building the index from scratch. When building an index on a bunch of identical int4range values (in my test, [1,10) ), the resulting index was about 17% smaller. If the current algorithm always chooses to insert on the left-most page, then it seems like there would be a half-filled right page for every split that occurs. Is that reasoning correct? However, I'm having some second thoughts about the run time for index builds. Maybe we should have a few more tests to determine if this should really be the default or just an option? > BTW, I don't much like the option name "randomization". It's not clear > what's been randomized. I'd prefer something like > "distribute_on_equal_penalty", although that's really long. Better ideas? I agree that "randomization" is vague, but I can't think of anything better. Regards,Jeff Davis
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