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help / color / mirror / Atom feedFrom: Jeff Davis <[email protected]>
To: Corey Huinker <[email protected]>
To: jian he <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Bruce Momjian <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Nathan Bossart <[email protected]>
Cc: Magnus Hagander <[email protected]>
Cc: Stephen Frost <[email protected]>
Cc: Ashutosh Bapat <[email protected]>
Cc: Peter Smith <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: [email protected]
Subject: Re: Statistics Import and Export
Date: Fri, 25 Oct 2024 15:18:48 -0700
Message-ID: <[email protected]> (raw)
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On Tue, 2024-09-17 at 05:02 -0400, Corey Huinker wrote:
>
> I've taken most of Jeff's work, reincorporated it into roughly the
> same patch structure as before, and am posting it now.
I have committed the import side of this patch series; that is, the
function calls that can load stats into an existing cluster without the
need to ANALYZE.
The pg_restore_*_stats() functions are designed such that pg_dump can
emit the calls. Some design choices of the functions worth noting:
(a) a variadic signature of name/value pairs rather than ordinary SQL
arguments, which makes it easier for future versions to interpret what
has been output from a previous version; and
(b) many kinds of errors are demoted to WARNINGs, to allow some
statistics to be set for an attribute even if other statistics are
malformed (also a future-proofing design); and
(c) we are considering whether to use an in-place heap update for the
relation stats, so that a large restore doesn't bloat pg_class -- I'd
like feedback on this idea
The pg_set_*_stats() functions are designed for interactive use, such
as tweaking statistics for planner testing, experimentation, or
reproducing a plan outside of a production system. The aforementioned
design choices don't make a lot of sense in this context, so that's why
the pg_set_*_stats() functions are separate from the
pg_restore_*_stats() functions. But there's a lot of overlap, so it may
be worth discussing again whether we should only have one set of
functions.
Regards,
Jeff Davis
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Subject: Re: Statistics Import and Export
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