RE: Index grows huge, possible leakage?
От | Mikheev, Vadim |
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Тема | RE: Index grows huge, possible leakage? |
Дата | |
Msg-id | 8F4C99C66D04D4118F580090272A7A234D32D9@sectorbase1.sectorbase.com обсуждение исходный текст |
Ответ на | Index grows huge, possible leakage? (Alfred Perlstein <bright@wintelcom.net>) |
Ответы |
Re: RE: Index grows huge, possible leakage?
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Список | pgsql-hackers |
> After several weeks our idicies grow very large (in one case to > 4-5 gigabytes) After droppping and recreating the indecies they > shrink back to something more reasonable (500megs same case). > > We are currently using Vadim's vacuum patches for VLAZY and MMNB, > against 7.0.3. We are using a LAZY vacuum on these tables > > However a normal (non-lazy) vacuum doesn't shrink the index, the > only thing that helps reduce the size is dropping and recreating. > > Is this a bug in 7.0.3? A possible bug in Vadim's patches? Or is > this somewhat expected behavior that we have to cope with? When index is created its pages are filled in full => any insert into such pages results in page split - ie in additional page. So, it's very easy to get 4Gb from 500Mb. Vacuum was never able to shrink indices - it just removes dead index tuples and so allows to re-use space ... if you'll insert the same keys. To know does VLAZY work properly or not I would need in vacuum debug messages. Did you run vacuum with verbose option or do you have postmaster' logs? With LAZY vacuum writes messages like Index _name_: deleted XXX unfound YYY YYY supposed to be 0... Vadim
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