HashAggregate row estimate = 200

From: Christophe Pettus <xof(at)thebuild(dot)com>
To: "pgsql-hackers(at)postgresql(dot)org Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: HashAggregate row estimate = 200
Date: 2016-06-04 02:10:44
Message-ID: 6307FB83-03AF-4ABE-9126-06790BC498EF@thebuild.com
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Something I've noticed frequently is that HashAggregate will, especially if the children are Append with one of the nodes a non-seqscan, estimate 200 rows rather than a calculated vlaue. Where is that value coming from? The statistics target, a hardwired constant, or something else?
--
-- Christophe Pettus
xof(at)thebuild(dot)com

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