Date: Fri, 6 Jan 2023 21:39:59 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Hari krishna Maddileti <hmaddileti@vmware.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Support for dumping extended statistics
Message-ID: <Y7jbf43jpAC37mpC@momjian.us>
References: <MN2PR05MB68795FCDB5B560D350084753B6FA9@MN2PR05MB6879.namprd05.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <MN2PR05MB68795FCDB5B560D350084753B6FA9@MN2PR05MB6879.namprd05.prod.outlook.com>
Archived-At: <https://www.postgresql.org/message-id/Y7jbf43jpAC37mpC%40momjian.us>
Precedence: bulk

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.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

Embrace your flaws.  They make you human, rather than perfect,
which you will never be.