From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael@paquier.xyz>
Cc: Euler Taveira <euler@eulerto.com>
Cc: nikolai.berkoff <nikolai.berkoff@pm.me>
Cc: pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
Subject: Re: ALTER TABLE ... SET DATA TYPE removes statistics
Date: Tue, 19 Oct 2021 12:16:44 -0300
Message-ID: <202110191516.eufiqzha2etw@alvherre.pgsql> (raw)
In-Reply-To: <YW5BDcUqz8kucDPr@paquier.xyz>
On 2021-Oct-19, Michael Paquier wrote:
> On Mon, Oct 18, 2021 at 05:15:59PM -0300, Euler Taveira wrote:
> > I agree that it might surprise an user and it would be good to document it.
> > However, it does not belong to the description. I would add it to the Notes
> > section at the end of the ALTER TABLE page.
>
> No objections to the suggested addition and the location of the
> addition (paragraph of SET DATA TYPE rather than "Notes"), but I think
> that the phrasing could be better:
> "The column's statistics are removed, hence a follow-up ANALYZE is
> suited to update the statistics to the new column type."
Dunno, putting it in the middle of the existing paragraph looks odd to
me. I would put it in a separate one instead, as in the attached.
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/Attachments:
[text/x-diff] datatype.patch (645B, ../202110191516.eufiqzha2etw@alvherre.pgsql/2-datatype.patch)
download | inline diff:diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgmlindex 81291577f8..86fc15c8b3 100644--- a/doc/src/sgml/ref/alter_table.sgml+++ b/doc/src/sgml/ref/alter_table.sgml@@ -198,6 +198,12 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
clause must be provided if there is no implicit or assignment
cast from old to new type.
</para>
++ <para>+ When this form is used, the column's statistics are removed,+ so running <command>ANALYZE</command> on the table afterwards+ is recommended.+ </para>
</listitem>
</varlistentry>
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Subject: Re: ALTER TABLE ... SET DATA TYPE removes statistics
In-Reply-To: <202110191516.eufiqzha2etw@alvherre.pgsql>
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