From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nathan Bossart <nathandbossart@gmail.com>
cc: Robert Haas <robertmhaas@gmail.com>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        Andrew Dunstan <andrew@dunslane.net>,
        pgsql-hackers@lists.postgresql.org
Subject: Re: Inefficiency in parallel pg_restore with many tables
In-reply-to: <20230913224753.GA1237642@nathanxps13>
References: <1225141.1690069670@sss.pgh.pa.us> <20230723055703.GA2421212@nathanxps13> <20230724190015.GA2528613@nathanxps13> <20230725185336.GA2911441@nathanxps13> <CA+TgmoYtJ+ad+ej=BCPWRNPyNoLy2R2O5wBSZUeyaQ54jrPk4A@mail.gmail.com> <20230901205248.GA3184752@nathanxps13> <20230902185521.GA3414119@nathanxps13> <20230904230829.GA3826808@nathanxps13> <2393313.1694363710@sss.pgh.pa.us> <20230913183450.GA1042742@nathanxps13> <20230913224753.GA1237642@nathanxps13>
Comments: In-reply-to Nathan Bossart <nathandbossart@gmail.com>
	message dated "Wed, 13 Sep 2023 15:47:53 -0700"
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Date: Wed, 13 Sep 2023 20:01:39 -0400
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Nathan Bossart <nathandbossart@gmail.com> writes:
> Upon closer inspection, I found a rather nasty problem.  The qsort
> comparator expects a TocEntry **, but the binaryheap comparator expects a
> TocEntry *, and we simply pass the arguments through to the qsort
> comparator.  In v9, I added the requisite ampersands.

Ooops :-(

> I'm surprised this
> worked at all.

Probably it was not sorting things appropriately.  Might be worth adding
some test scaffolding to check that bigger tasks are chosen before
smaller ones.

			regards, tom lane