Re: Various Questions

On Monday 01 December 2003 18:37, Evil Azrael wrote:
> 1) I have a transaction during which no data was modified, does it
> make a difference whether i send COMMIT or ROLLBACK? The effect is the
> same, but what´s about the speed?

It should not matter. Both commit and rollback should take same amount of
time..

> 2) Is there any general rule when the GEQO will start using an index?
> Does he consider the number of tuples in the table or the number of
> data pages? Or is it even more complex even if you don´t tweak the
> cost setting for the GEQO?

I thought GEQO was triggered by numebr of join clauses. That is what GEQO cost
indicates. It is not triggered by number of tuples in any table etc.

But correct me if I am wrong.

> 3) Makes it sense to add a index to a table used for logging? I mean
> the table can grow rather large due to many INSERTs, but is also
> seldom queried. Does the index slowdown noticable INSERTs?

Yes. It does make a lot of difference. If the table is very seldom queried,
you can probably create the index before querying and drop it later. However
even this will cost a seq. scan of table and can be heavy on performance..
Take your pick

Shridhar