Thread: Help with LIKE

I have a table with 8,628,633 rows that I'd LIKE to search (ha ha).

I have a very simple query:
  SELECT * FROM tableA WHERE column1 LIKE '%something%';

tableA.column1 has an index on it and the database has been vacuumed recently. My problem is with the output of
EXPLAIN:

+----------------------------------------------------------------+
|                         QUERY PLAN                             |
+----------------------------------------------------------------+
| Seq Scan on tableA  (cost=0.00..212651.61 rows=13802 width=46) |
|   Filter: (column1 ~~ '%something%'::text)                     |
+----------------------------------------------------------------+

I don't like that cost (2,12,651) at all! Is there anyway I can optimize this query? Make a different kind of index
(it'scurrently btree)? Use substr or indexof or something instead of LIKE? 

Thoughts?

--------------------------
David Olbersen
iGuard Engineer
11415 West Bernardo Court
San Diego, CA 92127
1-858-676-2277 x2152

David,

> I have a table with 8,628,633 rows that I'd LIKE to search (ha ha).
>
> I have a very simple query:
>   SELECT * FROM tableA WHERE column1 LIKE '%something%';

That's what's called an "unanchored text search".   That kind of query cannot
be indexed using a regular index.

What you need is called "Full Text Indexing" or "Full Text Search".   Check
out two resources:

1) contrib/tsearch in your PostgreSQL source code;
2) OpenFTS (www.openfts.org).

--
-Josh Berkus
 Aglio Database Solutions
 San Francisco