From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Inefficiency in parallel pg_restore with many tables
Date: Fri, 1 Sep 2023 13:52:48 -0700
Message-ID: <20230901205248.GA3184752@nathanxps13> (raw)
In-Reply-To: <CA+TgmoYtJ+ad+ej=BCPWRNPyNoLy2R2O5wBSZUeyaQ54jrPk4A@mail.gmail.com>
References: <20230718045701.GA1090171@nathanxps13>
<20230718160511.loirkf5fwjm5ut73@alvherre.pgsql>
<20230718160713.GA1139177@nathanxps13>
<20230720190644.GA1724613@nathanxps13>
<20230722231941.GA2020225@nathanxps13>
<1225141.1690069670@sss.pgh.pa.us>
<20230723055703.GA2421212@nathanxps13>
<20230724190015.GA2528613@nathanxps13>
<20230725185336.GA2911441@nathanxps13>
<CA+TgmoYtJ+ad+ej=BCPWRNPyNoLy2R2O5wBSZUeyaQ54jrPk4A@mail.gmail.com>
On Fri, Sep 01, 2023 at 04:00:44PM -0400, Robert Haas wrote:
> In hindsight, I think that making binaryheap depend on Datum was a bad
> idea. I think that was my idea, and I think it wasn't very smart.
> Considering that people have coded to that decision up until now, it
> might not be too easy to change at this point. But in principle I
> guess you'd want to be able to make a heap out of any C data type,
> rather than just Datum, or just Datum in the backend and just void *
> in the frontend.
Yeah, something similar to simplehash for binary heaps could be nice. That
being said, I don't know if there's a strong reason to specialize the
implementation for a given C data type in most cases. I suspect many
callers are just fine with dealing with pointers (e.g., I wouldn't store an
entire TocEntry in the array), and smaller types like integers are already
stored directly in the array thanks to the use of Datum. However, it
_would_ allow us to abandon this frontend/backend void */Datum kludge,
which is something.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, alvherre@alvh.no-ip.org, andrew@dunslane.net, pgsql-hackers@lists.postgresql.org
Subject: Re: Inefficiency in parallel pg_restore with many tables
In-Reply-To: <20230901205248.GA3184752@nathanxps13>
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