Joining two big tables

Database
Enthusiast

Joining two big tables

Hi All,
we have two big (1 billion +) tables both having same NUPI as: PRIMARY INDEX NUPI_X (Id )
PARTITION BY RANGE_N(Dt BETWEEN DATE '2007-1-01' AND DATE '2009-12-31' EACH INTERVAL '1' DAY , NO RANGE, UNKNOWN);

We preselect some subset of rows (15 millions) from one and need join it with second. I'd expect that PI will be utillised, but it uses
"sliding-window inclusion merge join (contexts = 8, 1)" for query like
SEL count(*) FROM A WHERE id IN (SEL id FROM B) or SEL count(*) FROM A INNER JOIN B On A.id=B.Id

Any tips how make it speedy?

Thank you for help

pH