From: | "Matthias Urlichs" <smurf(at)noris(dot)net> |
---|---|
To: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
Cc: | Matthias Urlichs <smurf(at)noris(dot)net>, Chris <chris(at)bitmead(dot)com>, Hannu Krosing <hannu(at)tm(dot)ee>, The Hermit Hacker <scrappy(at)hub(dot)org>, Alessio Bragadini <alessio(at)albourne(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Performance (was: The New Slashdot Setup (includes MySql server)) |
Date: | 2000-05-19 12:04:24 |
Message-ID: | 20000519140424.S27730@noris.de |
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Lists: | pgsql-general pgsql-hackers |
Hi,
Hiroshi Inoue:
>
> Maybe shared buffer isn't so large as to keep all the(4.1M) pg_index pages.
That seems to be the case.
> So it would read pages from disk every time, Unfortunately pg_index
> has no index to scan the index entries of a relation now.
>
Well, it's reasonable that you can't keep an index on the table which
states what the indices are. ;-)
... on the other hand, Apple's HFS file system stores all the information
about the on-disk locations of their files as a B-Tree in, in, you
guessed it, a B-Tree which is saved on disk as an (invisible) file.
Thus, the thing stores the information on where its sectors are located
at, inside itself.
To escape this catch-22 situation, the location of the first three
extents (which is usually all it takes anyway) is stored elsewhere.
Possibly, something like this would work with postgres too.
> However why is pg_index so large ?
>
Creating ten thousand tables will do that to you.
Is there an option I can set to increase the appropriate cache, so that
the backend can keep the data in memory?
--
Matthias Urlichs | noris network GmbH | smurf(at)noris(dot)de | ICQ: 20193661
The quote was selected randomly. Really. | http://smurf.noris.de/
--
Famous last words:
They'd never (be stupid enough to) make him a manager.
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