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From: Nathan Bossart <nathandbossart@gmail.com>
To: Hannu Krosing <hannuk@google.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Horribly slow pg_upgrade performance with many Large Objects
Date: Wed, 9 Jul 2025 12:53:48 -0500
Message-ID: <aG6srPib60NzJBeg@nathan> (raw)
In-Reply-To: <CAMT0RQStPtHfKwowd88Q0tynX0x=uJSKn=ihP8syhDJ6cH3DHQ@mail.gmail.com>
References: <4044567.1744128814@sss.pgh.pa.us>
	<CAMT0RQSALxZ2DJbq0b5cy+cvmpVxkawmv7c+qTWYObubZVr+2g@mail.gmail.com>
	<4047312.1744130263@sss.pgh.pa.us>
	<Z_VTucTiS01p-d6z@nathan>
	<4050387.1744132029@sss.pgh.pa.us>
	<aBkQLSkx1zUJ-LwJ@nathan>
	<aBtzZ4PyccUVCcyA@nathan>
	<CAMT0RQTXiqH7zdQEVSVd2L7_Cw4wQ1eHOD8hfZ+0vecMXJWc-w@mail.gmail.com>
	<aG2ISJC__3lQwRqY@nathan>
	<CAMT0RQStPtHfKwowd88Q0tynX0x=uJSKn=ihP8syhDJ6cH3DHQ@mail.gmail.com>

On Wed, Jul 09, 2025 at 04:52:16PM +0200, Hannu Krosing wrote:
> If you run it without the last WHERE it is reasonably fast. And it
> behaves the same as just inserting from the dump which also does not
> have any checks against duplicates.

With that change, the query is much faster, but my testing indicates that
it's still measurably slower than dumping and restoring the relevant
contents of pg_shdepend.

-- 
nathan





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