| From: | pinker <pinker(at)onet(dot)eu> |
|---|---|
| To: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>, Ilya Kazakevich <Ilya(dot)Kazakevich(at)JetBrains(dot)com> |
| Subject: | Re: Sequential vs. random values - number of pages in B-tree |
| Date: | 2016-08-18 12:03:02 |
| Message-ID: | 148637623-fed90107fc15e47e029254c7b364bdd4@pmq3v.m5r2.onet |
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| Lists: | pgsql-general |
W dniu 2016-08-18 14:00:31 użytkownik Ilya Kazakevich <Ilya(dot)Kazakevich(at)JetBrains(dot)com> napisał:
> Hi,
>
> >What's the reason that postgres needs more index pages to store random
> >data
> >than sequential ones?
>
> I assume that is because B-Tree is self-balanced tree, so it needs to be
> rebalanced after each insertion.
> Random insertions may go to the head of index where no space left leading to
> huge data moving.
> https://en.wikipedia.org/wiki/B-tree#Insertions_and_deletions
>
>
>
> Ilya Kazakevich
>
> JetBrains
> http://www.jetbrains.com
> The Drive to Develop
>
>
Thank you. So if that is the reason changing the fillfactor parameter should help?
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