Where to attach the WHERE statement

[lmtamina]

Good Morning,

What is more efficient and faster , attaching my WHERE clause to the SET statement or within the DATA step, which is what I am currently using ? I reading from a dataset using a hash table . Appreciate any advice. Thanks

data USI_CLAIMS_DATA;

length CPT_CODE $5.;

if _N_ =1 then do;

DECLARE HASH H(dataset:'USI_CPTCODES');

H.DEFINEKEY ('CPT_CODE');

H.DEFINEDONE();

end;

SET CLAIMS_MASTER(keep=&claims_header);

where serv_from_date ge '1Jan2014'd;

if H.find(key:hcpcs_cpt4_base_cd1) = 0 then output;

run;

[Reeza · Accepted solution]

It is more efficient to place it in the SET statement because then the data is filtered before you start processing it. This can be noted as using a DATA SET OPTION vs a WHERE statement.