SQL Performance Optimization

Hi.

I have to SELECTs, both returning a key column in their result set. What I want is a join/intersection of both. The first result set is rather large, nonunique and comes from an expensive query so i want to avoid any sorting. The second ist just a SELECT ID FROM TABLE where the TABLE has an unique index.

I want to get the first rows ASAP.

The best strategy to get what i want is probaby to run along the first result set and to do lookups into the second table to see if the id is in it and to set a "have seen it flag". If I look up the same entry a second time I behave as if it is not there. This way i would get uniqueness without sorting.

This looks like a very unSELECTish strategy. Is there any way to write a SELECT that uses it (on 8.0.5).

Thanx,
Joachim

-- 
SELECT COUNT(1) FROM HIMMELSZELT.STERNE;

Althoug this message has a valid From header, replies 
to user_at_netcologne.de where user = nc-zobeljo are preferred.