On Thu, Jan 12, 2006 at 01:35:07PM +0100, Alessandro Baretta wrote:
Ott? Havasv?lgyi wrote:
Hi all,
Is PostgreSQL able to throw unnecessary joins?
For example I have two tables, and I join then with their primary keys,
say type of bigint . In this case if I don't reference to one of the
On Thu, Jan 12, 2006 at 07:51:22PM +0100, Ott? Havasv?lgyi wrote:
Hi,
If the join is to a primary key or notnull unique column(s), then
inner join is also ok. But of course left join is the simpler case.
An example:
Actually, you need both the unique/pk constraint, and RI (a fact I
missed
Hi all,
Is PostgreSQL able to throw unnecessary joins?
For example I have two tables, and I join then with their primary keys, say type of bigint. In this case if I don't reference to one of the tablesanywhere except the join condition, thenthe join can be eliminated.
Or if I do a table1 left
Ottó Havasvölgyi wrote:
Hi all,
Is PostgreSQL able to throw unnecessary joins?
For example I have two tables, and I join then with their primary keys,
say type of bigint . In this case if I don't reference to one of the
tables anywhere except the join condition, then the join can be
Hi,
As far as I know SQL Server has some similar feature. It does not join
if not necessary, more exactly: if the result would be the same if it
joined the table.
Here is another example:
http://www.ianywhere.com/developer/product_manuals/sqlanywhere/0902/en/html/dbugen9/0468.htm
This would be
=?ISO-8859-1?Q?Ott=F3_Havasv=F6lgyi?= [EMAIL PROTECTED] writes:
As far as I know SQL Server has some similar feature. It does not join
if not necessary, more exactly: if the result would be the same if it
joined the table.
I find it really really hard to believe that such cases arise often
Dear Tom,
Not sure about Otto's exact problem, but he did mention views, and I'd feel
more comfortable if you told me that view-based queries are re-planned based
on actual conditions etc. Are they?
Also, if you find it unlikely (or very rare) then it might be a configurable
parameter. If
Hi,
I think it would be sufficient only for views. In other cases the
programmer can optimize himself. But a view can be a join of other
tables, and it is not sure that all of them are always needed. It all
depends on what I select from the view.
This information could even be calculted at view
On Thu, 2006-01-12 at 11:00, Ottó Havasvölgyi wrote:
Hi,
I think it would be sufficient only for views. In other cases the
programmer can optimize himself. But a view can be a join of other
tables, and it is not sure that all of them are always needed. It all
depends on what I select from
Hi,
If the join is to a primary key or notnull unique column(s), then
inner join is also ok. But of course left join is the simpler case.
An example:
create table person (id serial primary key, name varchar not null);
create table pet (id serial primary key, name varchar not null,
person_id int
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