From: | tgl(at)postgresql(dot)org (Tom Lane) |
---|---|
To: | pgsql-committers(at)postgresql(dot)org |
Subject: | pgsql: Tweak tsmatchsel() so that it examines the structure of the |
Date: | 2010-07-31 03:27:49 |
Message-ID: | 20100731032749.17AC27541D5@cvs.postgresql.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-committers |
Log Message:
-----------
Tweak tsmatchsel() so that it examines the structure of the tsquery whenever
possible (ie, whenever the tsquery is a constant), even when no statistics
are available for the tsvector. For example, foo @@ 'a & b'::tsquery
can be expected to be more selective than foo @@ 'a'::tsquery, whether
or not we know anything about foo. We use DEFAULT_TS_MATCH_SEL as the assumed
selectivity of individual query terms when no stats are available, then
combine the terms according to the query's AND/OR structure as usual.
Per experimentation with Artur Dabrowski's example. (The fact that there
are no stats available in that example is a problem in itself, but
nonetheless tsmatchsel should be smarter about the case.)
Back-patch to 8.4 to keep all versions of tsmatchsel() in sync.
Tags:
----
REL9_0_STABLE
Modified Files:
--------------
pgsql/src/backend/tsearch:
ts_selfuncs.c (r1.7 -> r1.7.6.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/ts_selfuncs.c?r1=1.7&r2=1.7.6.1)
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2010-07-31 03:27:57 | pgsql: Tweak tsmatchsel() so that it examines the structure of the |
Previous Message | Tom Lane | 2010-07-31 03:27:40 | pgsql: Tweak tsmatchsel() so that it examines the structure of the |