Hmmm, you're right. Is there any way to do a explain select * from id_val_tbl where false
while explain doesn't tell SEQ_SCAN? I have to admit that I didn't performance tested this. I just saw explain writing SEQ_SCAN. |-----Original Message----- |From: Tom Lane [mailto:[EMAIL PROTECTED] |Sent: Mittwoch, 20. April 2005 23:06 |To: Tambet Matiisen |Cc: KÖPFERL Robert; pgsql-sql@postgresql.org |Subject: Re: [SQL] Function to either return one or all records | | |"Tambet Matiisen" <[EMAIL PROTECTED]> writes: |> Standard technique is to rewrite OR queries to UNION |queries. I believe PostgreSQL optimizer does not do that |automatically. So you could try instead: | |> select * from id_bal_tbl where $1 is null |> union all |> select * from id_bal_tbl where id = $1; | |... but that won't do anything to solve the performance problem. |Doesn't help for the second select to use an index, if the first |one grovels over the whole table anyway ... | | regards, tom lane | ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
