Re: [PATCHES] Patch for database locale settings - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [PATCHES] Patch for database locale settings
Date
Msg-id 200505071545.j47Fj2H16090@candle.pha.pa.us
Whole thread Raw
In response to Re: [PATCHES] Patch for database locale settings  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Description added to TODO:

    * Allow locale to be set at database creation

      Currently locale can only be set during initdb.  No global tables have
      locale-aware columns.  However, the database template used during
      database creation might have locale-aware indexes.  The indexes would
      need to be reindexed to match the new locale.

---------------------------------------------------------------------------

Tom Lane wrote:
> Alvaro Herrera <alvherre@dcc.uchile.cl> writes:
> > Maybe it would work if we forced indexes on shared relations to be
> > scanned using a fixed collation.
>
> The shared relations only have indexes on name, oid, and integer:
> select distinct atttypid::regtype
> from pg_class c join pg_attribute a on c.oid = a.attrelid
> where relisshared and relkind = 'i';
> and name has non-locale-sensitive ordering rules anyway.  So that's
> not the big problem; we could probably get away with decreeing that
> name will always be that way and that shared relations can't have
> locale-dependent indexes.
>
> The big problem (and the reason why this idea has been shot down in
> the past) is that CREATE DATABASE can't change the locale from what it
> is in the template database unless it's prepared to reindex any locale-
> sensitive indexes in the non-shared part of the template database.
> Which would be a difficult undertaking seeing that we can't even connect
> to the copied database until after commit.
>
> We could maybe say that we will never have any locale-dependent indexes
> at all on any system catalog, but what of user-defined tables in
> template databases?  It would simply not work to do something as simple
> as creating a table with an indexed text column in template1.
>
> On the other hand you could argue that people already run the same kind
> of risk when changing database encoding at CREATE, which is a feature
> that's been there a long time and hasn't garnered many complaints.
> Not so much that their indexes will break as that their data will.
> So perhaps we should be willing to document "don't do that".  Certainly
> it would be a lot more useful if both locale and encoding could be set
> per-database.
>
>             regards, tom lane
>
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