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From: Euler Taveira <euler@timbira.com.br>
Date: Mon, 25 Nov 2019 10:51:23 -0300
Message-ID: 
 <CAHE3wggE-k5y2Gnu45soTi5vJsJY12zqVZ_-VwNPHxtsUgFMrA@mail.gmail.com>
Subject: Re: Add <caution> for ALTER TEXT SEARCH CONFIGURATION
To: Jeff Janes <jeff.janes@gmail.com>
Cc: pgsql-docs@postgresql.org
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Em sex., 15 de nov. de 2019 =C3=A0s 16:10, Jeff Janes
<jeff.janes@gmail.com> escreveu:
>
> If you alter one of the built-in text search configurations, the modifica=
tions to it will not get dumped by pg_dump, and thus won't get propagated b=
y pg_upgrade leading to silent behavior changes in the new cluster (as well=
 in any other type of restoration from pg_dump output)
>
It was a bad design to allow changes in builtin text search objects.
User expects that all modifications should be propagated while dumping
a cluster.

Since pg_ts_config_map does not have an oid column, it is not easy to
guess that a text search configuration was modified (unless we dump
the initial table and compare row-by-row). We could disallow changes
in builtin text search objects but it could potentially break some
scenarios. Even if it breaks a scenario, a workaround with another
user-defined text search configuration is possible.

> I would say it is bad practise to alter one of those anyway, rather than =
copy and alter the copy.  But I wasn't aware until now of just how bad of a=
n idea it was.  I think that this needs to be warned about in the docs for =
ALTER TEXT SEARCH CONFIGURATION.  If I were monkeying around in $SHAREDLIB/=
tsearch_data, I'd expect traps like this, but not when executing things fro=
m SQL after reading the docs on the command.
>
Let's start with a tangible idea: add a big "caution" and also a
WARNING while ALTER TEXT SEARCH CONFIGURATION whose schema is
pg_catalog.


--=20
   Euler Taveira                                   Timbira -
http://www.timbira.com.br/
   PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento