From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Henrik Cednert (Filmlance)" <henrik.cednert@filmlance.se>
cc: "pgsql-performance@lists.postgresql.org"
 <pgsql-performance@lists.postgresql.org>
Subject: Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
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Comments: In-reply-to "Henrik Cednert (Filmlance)"
 <henrik.cednert@filmlance.se>
	message dated "Tue, 21 Nov 2017 14:28:43 +0000"
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Date: Tue, 21 Nov 2017 12:01:27 -0500
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"Henrik Cednert (Filmlance)" <henrik.cednert@filmlance.se> writes:
> The last pg_dump with 8.4 took 212 minutes and 49 seconds.And now with 9=
.5 the very same pg_dump takes 644 minutes and 40 seconds. To it takes abo=
ut three times as long now and I have no idea to why. Nothing in the syste=
m or hardware other than the pgsql upgrade have change.

Can you get a profile of where the machine is spending its time during the
dump run?  On Linux I'd recommend "perf", but on macOS, hmm ...
You could use Activity Monitor, but as far as I can see that just captures
short-duration snapshots, which might not be representative of a 10-hour
run.  XCode's Instruments feature would probably be better about giving
a full picture, but it has a steep learning curve.

			regards, tom lane