Re: Reindex doesn't eliminate bloat

From: Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
To: Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net>, pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: Reindex doesn't eliminate bloat
Date: 2018-03-12 22:55:39
Message-ID: d70fa807-a785-beb5-ea8b-127418cb420c@aklaver.com
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On 03/12/2018 03:05 PM, Ron Johnson wrote:
> v8.4.12
>
> According to this (https://pastebin.com/TJB32n5M) query, which I thought
> I got from https://wiki.postgresql.org/wiki/Index_Maintenance, a list of
> indexes and their bloat is generated.
>
> After reindexing a table with a large amount of reported bloat (column
> bloat_pct says 29%), re-running the query shows no change in the amount

First I am not seeing a column bloat_pct in the query you linked to, so
are you sure that is the actual query you used?

> of bloat.  This is a historical table, and VACUUM VERBOSE shows that
> there's nothing to free up.
>
> Is this something that I must live with, or am I misinterpreting the query?

Honestly I have not worked my way in depth through the query you show,
though I did notice it uses pg_stats. What happens if run ANALYZE
(https://www.postgresql.org/docs/8.4/static/sql-analyze.html) to update
the stats?

>
> Thanks,
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com

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