Hi, I'm trying to create a benchmark MonetDB vs Postgres and for many types of queries, MonetDB quite faster than Postgres.But there is an interesting result when i try a query which contains an 'in' statement.The response times are MonetDB - 58 sec Postgres - 3 sec for the query : select RFOADV_10.rfoadvsup as c0, sum((case when cabact___rfountide = 'NB_E' then cabactqte else 0 end)) as m0 from RFOADV as RFOADV_10, CABACT as CABACT where (cabact___rforefide = 'FHSJ' and cabact___rteprcide = 'CPTANA' and cabact___rtestdide = '100' and cabact___rfovsnide = '200805_001') and CABACT.cabact_c2rfodstide = RFOADV_10.rfoadvinf and RFOADV_10.rfoadvsup in ('5030', '5031', '5032', '5033', '5034', '5035', '5036', '5037', '5038') group by RFOADV_10.rfoadvsup i reform the query so that it can give the same result without 'in' : select RFOADV_10.rfoadvsup as c0, sum((case when cabact___rfountide = 'NB_E' then cabactqte else 0 end)) as m0 from RFOADV as RFOADV_10 join CABACT on (CABACT.cabact_c2rfodstide = RFOADV_10.rfoadvinf) join (select '5031' as pole UNION select '5032' as pole UNION select '5033' as pole UNION select '5034' as pole UNION select '5035' as pole UNION select '5036' as pole UNION select '5037' as pole UNION select '5038' as pole ) sub ON (RFOADV_10.rfoadvsup = sub.pole) where (cabact___rforefide = 'FHSJ' and cabact___rteprcide = 'CPTANA' and cabact___rtestdide = '100' and cabact___rfovsnide = '200805_001') group by RFOADV_10.rfoadvsup the response time for MonetDB decreases 100 times (0.6 sec). Do you have any idea about it ? I run both Monetdb and Postgres on a server with 10GB Ram and the tables have CABACT : 677000 RFOADV : 140000 rows. Thanks, Mehmet -- Open WebMail Project (http://openwebmail.org)