pgsql: Second pass at improving LIKE/regex estimation in non-C locales. - Mailing list pgsql-committers

From tgl@postgresql.org (Tom Lane)
Subject pgsql: Second pass at improving LIKE/regex estimation in non-C locales.
Date
Msg-id 20071109201002.3BB507540F0@cvs.postgresql.org
Whole thread Raw
List pgsql-committers
Log Message:
-----------
Second pass at improving LIKE/regex estimation in non-C locales.  It turns
out that it's actually quite likely that a string that is an extension of
the given prefix will sort as larger than the "greater" string our previous
code created.  To provide some defense against that, do the comparisons
against a modified string instead of just the bare prefix.  We tack on
"Z", "z", "y", or "9", whichever is seen as largest in the current locale.
Testing suggests that this is sufficient at least for cases involving
ASCII data.

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        selfuncs.c (r1.238 -> r1.239)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/selfuncs.c?r1=1.238&r2=1.239)

pgsql-committers by date:

Previous
From: Gregory Stark
Date:
Subject: Re: pgsql: If an index depends on no columns of its table, give it a
Next
From: tgl@postgresql.org (Tom Lane)
Date:
Subject: pgsql: Second pass at improving LIKE/regex estimation in non-C locales.