On Tue, 25 Jan 2005 07:23 pm, Antony Paul wrote: > Creating an index and using lower(column) does not change the explain > plan estimates. > It seems that it is not using index for like or ilike queries > irrespective of whether it have a pattern matching character in it or > not. (using PostgreSQL 7.3.3) > > On googling I found this thread > > http://archives.postgresql.org/pgsql-sql/2004-11/msg00285.php > > It says that index is not used if the search string begins with a % symbol.
What exactly are the type of like queries you are going? there is a solution for having the % at the start, but you can win everyway. > > rgds > Antony Paul > > On Mon, 24 Jan 2005 20:58:54 +1100, Russell Smith <[EMAIL PROTECTED]> wrote: > > On Mon, 24 Jan 2005 08:18 pm, Antony Paul wrote: > > > Hi, > > > I have a query which is executed using ilike. The query values are > > > received from user and it is executed using PreparedStatement. > > > Currently all queries are executed as it is using iilike irrespective > > > of whether it have a pattern matching character or not. Can using = > > > instead of ilike boot performance ?. If creating index can help then > > > how the index should be created on lower case or uppercase ?. > > > > > It depends on the type of queries you are doing. > > > > changing it to something like lower(column) like lower('text%'), and > > creating an index on lower(column) will give you much better performance. > > > > If you have % in the middle of the query, it will still be slow, but I > > assume that is not > > the general case. > > > > I am not sure what the effect of it being prepared will be, however I've > > had much success > > with the method above without the queries being prepared. Others may be > > able to offer advice > > about if prepare will effect it. > > > > Regards > > > > Russell Smith > > > > ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly