Re: Function to either return one or all records - Mailing list pgsql-sql

"Tambet Matiisen" <t.matiisen@aprote.ee> 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