Re: pg_migrator and an 8.3-compatible tsvector data type

Josh Berkus wrote:
> Bruce,
> 
> > The ordering of the lexems was changed:
> >
> >     /*
> >      * Convert 8.3 tsvector to 8.4
> >      *
> >      * 8.3 sorts lexemes by its length and if lengths are the same then it uses
> >      * alphabetic order;  8.4 sorts lexemes in lexicographical order, e.g.
> >      *
> >      * =>  SELECT 'c bb aaa'::tsvector;
> >      *     tsvector
> >      * ----------------
> >      *  'aaa' 'bb' 'c'         -- 8.4
> >      *  'c' 'bb' 'aaa'         -- 8.3
> >      */
> 
> What does that get us in terms of performance etc.?
> 
> Given that it's going to prevent users of Tsearch from 
> upgrading-in-place, the format change ought to be giving us some serious 
> gains.  Otherwise we should put it off until we need to make other 
> datatype changes.

No idea but now that we are in beta we would then be invalidating beta
tester data.  The area I got stuck on is that there is no CAST behavior
when creating an index.  We are already invalidating GIN indexes, but I
can't even create an index to support the old data type.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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