Re: Add <caution> for ALTER TEXT SEARCH CONFIGURATION

Em sex., 15 de nov. de 2019 às 16:10, Jeff Janes
<jeff(dot)janes(at)gmail(dot)com> escreveu:
>
> If you alter one of the built-in text search configurations, the modifications to it will not get dumped by pg_dump, and thus won't get propagated by 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 an 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 from 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.

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