Re: Surprising dead_tuple_count from pgstattuple

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Gordon Shannon <gordo169(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Surprising dead_tuple_count from pgstattuple
Date: 2010-08-09 17:50:28
Message-ID: 1281376228.2142.1232.camel@ebony
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On Sat, 2010-08-07 at 16:11 -0700, Gordon Shannon wrote:

> So, I guess my real question here is, what happened to the "missing"
> 100 items? If it was HOT prune, can anyone summarize what that does?

Itagaki already explained that the second DELETE would have removed the
100 dead rows you consider to be missing.

Any SQL statement that reads a block can do HOT pruning, if the block is
otherwise unlocked.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Training and Services

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