pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Arthur Zakirov <a.zakirov@postgrespro.ru>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Pavel Stehule <pavel.stehule@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PROPOSAL] Shared Ispell dictionaries
Date: Mon, 25 Feb 2019 14:33:10 +0300
Message-ID: <5902bb0c-b3aa-acc4-4324-e33735c4e5a8@postgrespro.ru> (raw )
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On 21.02.2019 19:13, Robert Haas wrote:
> So I think it's better to have each backend locally make a decision
> about when that particular backend no longer needs the dictionary, and
> then let the system automatically clean up the ones that are needed by
> nobody.
Yep, it wouldn't be hard to implement.
> Perhaps a better approach still would be to do what Andres proposed
> back in March:
>
> #> Is there any chance we can instead can convert dictionaries into a form
> #> we can just mmap() into memory? That'd scale a lot higher and more
> #> dynamicallly?
>
> The current approach inherently involves double-buffering: you've got
> the filesystem cache containing the data read from disk, and then the
> DSM containing the converted form of the data. Having something that
> you could just mmap() would avoid that, plus it would become a lot
> less critical to keep the mappings around. You could probably just
> have individual queries mmap() it for as long as they need it and then
> tear out the mapping when they finish executing; keeping the mappings
> across queries likely wouldn't be too important in this case.
>
> The downside is that you'd probably need to teach resowner.c about
> mappings created via mmap() so that you don't leak mappings on an
> abort, but that's probably not a crazy difficult problem.
It seems to me Tom and Andres also vote for the mmap() approach. I think
I need to look closely at the mmap().
I've labeled the patch as 'v13'.
--
Arthur Zakirov
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company
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Cc: a.zakirov@postgrespro.ru, robertmhaas@gmail.com, tomas.vondra@2ndquadrant.com, andres@anarazel.de, tgl@sss.pgh.pa.us, pavel.stehule@gmail.com
Subject: Re: [PROPOSAL] Shared Ispell dictionaries
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