Re: AW: [HACKERS] mmap and MAP_ANON

From: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
To: andreas(dot)zeugswetter(at)telecom(dot)at (Andreas Zeugswetter)
Cc: hackers(at)postgreSQL(dot)org
Subject: Re: AW: [HACKERS] mmap and MAP_ANON
Date: 1998-05-14 14:55:34
Message-ID: 199805141455.KAA09202@candle.pha.pa.us
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>
> >> - Could we use mmap:ing of files at a higher level then
> >> src/backend/strorage/ipc/ipc.c to get even better performance
> >> and cleaness?
> >
> >Yes, we could use mmap() to map the actual files. I will post time
> >timings on this soon.
>
> I do not think this will be a practicable solution, since it would mean the whole db
> has to mmap'ed. This means there has to be enough virtual memory to hold
> the complete database, or at least one table at a time. Or do I understand this wrong ??

We can map parts of the table, even in 8k chunks. However, looking at
my sequential scan timing tests, it would be slower.

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