Subject: Re: Support for dumping extended statistics

From: Hari krishna Maddileti <[email-masked]>
Date: Tue, 10 Jan 2023 11:28:36 +0000

Thanks Team for showing interest.

Please find the attached patch, which uses the same approach as mentioned in previous email to implement input functions to parse pg_distinct, pg_dependency and pg_mcv_list strings.

Regards,
Hari
From: Bruce Momjian <[email-masked]>
Date: Saturday, 7 January 2023 at 8:10 AM
To: Hari krishna Maddileti <[email-masked]>
Cc: PostgreSQL Hackers <[email-masked]>
Subject: Re: Support for dumping extended statistics
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On Thu, Jan  5, 2023 at 06:29:03PM +0000, Hari krishna Maddileti wrote:
> Hi Team,
> In order to restore dumped extended statistics (stxdndistinct,
> stxddependencies, stxdmcv) we need to provide input functions to parse
> pg_distinct/pg_dependency/pg_mcv_list strings.
>
> Today we get the ERROR "cannot accept a value of type pg_ndistinct/
> pg_dependencies/pg_mcv_list" when we try to do an insert of any type.
>
> Approch tried:
>
> - Using yacc grammar file (statistics_gram.y) to parse the input string to its
> internal format for the types pg_distinct and pg_dependencies
>
> - We are just calling byteain() for serialized input text of type pg_mcv_list.
>
> Currently the changes are working locally,  I would like to push the commit
> changes to upstream if there any usecase for postgres.   Would like to know if
> there any interest from postgres side.

There is certainly interest in allowing the optimizer statistics to be
dumped and reloaded.  This could be used by pg_restore and pg_upgrade.

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