Re: Heavily modified big table bloat even in auto vacuum is running - Mailing list pgsql-hackers

From Haribabu kommi
Subject Re: Heavily modified big table bloat even in auto vacuum is running
Date
Msg-id 8977CB36860C5843884E0A18D8747B0372BDAFDF@szxeml558-mbs.china.huawei.com
Whole thread Raw
In response to Re: Heavily modified big table bloat even in auto vacuum is running  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: Heavily modified big table bloat even in auto vacuum is running
List pgsql-hackers
On 12 November 2013 08:47 Amit Kapila wrote:
> On Mon, Nov 11, 2013 at 3:14 PM, Haribabu kommi
> <haribabu.kommi@huawei.com> wrote:
> > On 08 November 2013 18:35 Amit Kapila wrote:
> >> On Fri, Nov 8, 2013 at 10:56 AM, Haribabu kommi
> >> <haribabu.kommi@huawei.com> wrote:
> >> > On 07 November 2013 09:42 Amit Kapila wrote:
> >> > 1. Taking a copy of n_dead_tuples before VACUUM starts and then
> >> subtract it once it is done.
> >> >    This approach doesn't include the tuples which are remains
> >> > during
> >> the vacuum operation.

Patch is modified as take a copy of n_dead_tuples during vacuum start and use
the same while calculating the new dead tuples at end of vacuum.

> >> By the way, do you have test case or can you try to write a test
> case
> >> which can show this problem and then after fix, you can verify if
> the
> >> problem is resolved.
> >
> > The simulated index bloat problem can be generated using the attached
> script and sql.
> > With the fix of setting the dead tuples properly,
>
>    Which fix here you are referring to, is it the one which you have
> proposed with your initial mail?
>
> > the bloat is reduced and by changing the vacuum cost Parameters the
> > bloat is avoided.

With the simulated bloat test run for 1 hour the bloat occurred as below,

Unpatched - 1532MB
Patched   - 1474MB

With this patched approach the bloat is reduced.

Regards,
Hari babu.



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