Re: Need help understanding vacuum verbose output

From: Gordon Shannon <gordo169(at)gmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Need help understanding vacuum verbose output
Date: 2010-08-06 17:56:33
Message-ID: 1281117393224-2266912.post@n5.nabble.com
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> That last message prints tups_vacuumed, but those other ones are counting
> all the removed item pointers. So apparently Gordon had a whole lot of
> pre-existing DEAD item pointers. I wonder why ...

Perhaps this will help. Here's the entire test.

Start with a newly loaded table with 5,063,463 rows.
1. delete 467 rows
2. delete 4,220 rows
3. vacuum
4. delete 5,091 rows
5. delete 3,832 rows
6. delete 10,168 rows
7. delete 10,469 rows
8. delete 16,318 rows
9. vacuum (output shown in original post)

> 13 There were 4687 unused item pointers.

This corresponds to the 1st 2 steps, I presume, where the 4687 unused
pointer were created by the 1st vacuum.

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