From: Tom Lane <tgl@sss.pgh.pa.us>
To: Julien Rouhaud <rjuju123@gmail.com>
cc: Andrew Dunstan <andrew@dunslane.net>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        David Rowley <dgrowleyml@gmail.com>, Peter Geoghegan <pg@bowt.ie>,
        Robert Haas <robertmhaas@gmail.com>,
        pgsql-hackers@lists.postgresql.org,
        Andrew <pgsqlhackers@andrewrepp.com>
Subject: Re: pg_dump versus hash partitioning
In-reply-to: <20230311030154.pg63uspio35h4a6t@jrouhaud>
References: <CA+TgmoYoSoX8bN_yzabmRDQBNxEaWmjBKPnkZPMUDpPTBy=d4A@mail.gmail.com> <CAH2-WzkjKCmVD9JDKHx09YC+c5kSL_1rHH0kRMyvDHRFoxgw6Q@mail.gmail.com> <CA+TgmoYJ+3XpW_iYapXN3gwq2MECi7GH8BxuwKFCQPOzLaa3OQ@mail.gmail.com> <CAH2-Wz=cMRoYHeoac7kscdDNBSYzHKgMvSHX5CFEoE66rimk8A@mail.gmail.com> <1425446.1675291093@sss.pgh.pa.us> <CAApHDvqJM5HxhZSnxESENAHLxTZ=eXKKHxeHfvVe1E8v28woDA@mail.gmail.com> <1440373.1675299790@sss.pgh.pa.us> <a7ef6212-f9fe-6826-9640-5dac54327140@dunslane.net> <1533086.1675349554@sss.pgh.pa.us> <1912821.1676402493@sss.pgh.pa.us> <20230311030154.pg63uspio35h4a6t@jrouhaud>
Comments: In-reply-to Julien Rouhaud <rjuju123@gmail.com>
	message dated "Sat, 11 Mar 2023 11:01:54 +0800"
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Date: Fri, 10 Mar 2023 22:10:14 -0500
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Julien Rouhaud <rjuju123@gmail.com> writes:
> Working on some side project that can cause dump of hash partitions to b=
e
> routed to a different partition, I realized that --load-via-partition-ro=
ot can
> indeed cause deadlock in such case without FK dependency or anything els=
e.

> The problem is that each worker will perform a TRUNCATE TABLE ONLY follo=
wed by
> a copy of the original partition's data in a transaction, and that obvio=
usly
> will lead to deadlock if the original and locked partition and the resto=
red
> partition are different.

Oh, interesting.  I wonder if we can rearrange things to avoid that.

			regards, tom lane