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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Suya Huang <shuang@connexity.com>
cc: Claudio Freire <klaussfreire@gmail.com>,
        "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: what's the slowest part in the SQL
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Comments: In-reply-to Suya Huang <shuang@connexity.com>
	message dated "Wed, 10 Aug 2016 01:43:54 -0000"
Date: Tue, 09 Aug 2016 21:57:45 -0400
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Suya Huang <shuang@connexity.com> writes:
> Thank you Tom very much, that’s the piece of information I miss. 
> So, should I expect that the nested loop join would be much faster if I cache both tables (use pg_prewarm) into memory as it waives the disk read?

pg_prewarm is not going to magically fix things if your table is bigger
than RAM, which it apparently is.

			regards, tom lane


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