alves wrote: > Hi guys. > > Need to make a stange merge, and having some problems how to do it (at > least with datasteps). > > I have 2 datasets (treatment and no-treatment) and I need to merge the > datasets in a way that each observation in the treatment dataset will > be merged with all no-treatment patients with the same age. some > treatments patients have the same age and when the age repeats I need > again all no-treatment patients. > > Datasets are pretty big so I trying to find a way that optimises > speed.

Have you reached some bottleneck or case where a current method takes "too long".

How big is big? - How many rows and columns in each table? - Does one table consistently have more rows than the other ?

Are the tables indexed?

What have you tried, if anything?

Was it anything like a left join? ---------------------------------- data one(index=(focus1=(id1 id2) age)); input id1 $ id2 $ age; cards; a xx 25 a yy 30 c tt 25 d tt 35 e zz 40 run;

data two (index=(id age)); input id age; cards; 1 25 2 25 3 30 4 35 5 35 6 25 7 25 8 30 run;

options msglevel=I;

proc sql; create table three as select one.*, two.id from one left join two on one.age = two.age order by id1, id2, id ; quit; ----------------------------------

There are many other ways to join data.

Richard A. DeVenezia http://www.devenezia.com/