On Tue, 23 Mar 2004, Phil Endecott wrote:
Dear PostgresQL Experts,
I am trying to get to the bottom of some efficiency problems and hope that
you can help. The difficulty seems to be with INTERSECT expressions.
I have a query of the form
select A from T where C1 intersect select A
On Tue, 23 Mar 2004, Stephan Szabo wrote:
On Tue, 23 Mar 2004, Phil Endecott wrote:
Dear PostgresQL Experts,
I am trying to get to the bottom of some efficiency problems and hope that
you can help. The difficulty seems to be with INTERSECT expressions.
I have a query of the form
I asked:
select A from T where C1 intersect select A from T where C2;
select A from T where C1 and C2;
[why isn't the first optimised into the second?]
Stephan Szabo answered:
Given a non-unique A, C1 as B5, c2 as C5 and the data:
A | B | C
1 | 6 | 1
1 | 1 | 6
The intersect gives 1 row,
On Tue, Mar 23, 2004 at 11:21:39 -0500,
Phil Endecott [EMAIL PROTECTED] wrote:
Does anyone have any suggestions about how to do this? I'd like a nice
general technique that works for all possible subqueries, as my current
composition with INTERSECT does.
One adjustment you might make is
Bruno Wolff III [EMAIL PROTECTED] writes:
On Tue, Mar 23, 2004 at 11:21:39 -0500,
Phil Endecott [EMAIL PROTECTED] wrote:
Does anyone have any suggestions about how to do this? I'd like a nice
general technique that works for all possible subqueries, as my current
composition with INTERSECT
Phil,
So I suppose I'll have to find a more sophisticated way to generate my
queries. Imagine a user interface for a search facility with various
buttons and text entry fields. At the moment, for each part of the search
that the user has enabled I create a string of SQL. I then compose
