I tested on two other server with the same data. I have the same bug Server 3 : Jan2014-SP2 Welcome to mclient, the MonetDB/SQL interactive terminal (Jan2014-SP2) Database: MonetDB v11.17.17 (Jan2014-SP2), 'mapi:monetdb://rd:50000/lemonde' Type \q to quit, \? for a list of available commands auto commit mode: on sql>CREATE TABLE tmp__pierre5 AS ( SELECT id_unique, Device, COUNT(*) AS NBVISISTES FROM donnees_lmd_pierre GROUP BY id_unique, Device ) WITH DATA; operation successful (9m 4s) Server 4 : Oct2014-SP1 Welcome to mclient, the MonetDB/SQL interactive terminal (Oct2014-SP1) Database: MonetDB v11.19.7 (Oct2014-SP1), 'mapi:monetdb://poledev:50000/lemonde' Type \q to quit, \? for a list of available commands auto commit mode: on sql>CREATE TABLE tmp__pierre5 AS ( SELECT id_unique, Device, COUNT(*) AS NBVISISTES FROM donnees_lmd_pierre GROUP BY id_unique, Device ) WITH DATA; The query runs from 10 hours is what you want to dump the table for download ? Pierre -- 1G6 52 route de bischwiller 67300 Schiltigheim Société de Services et de Formations en Logiciels Libres http://1g6.biz Tél : 06 64 63 70 35 ----- Mail original ----- De: "Pierre-Adrien Coustillas" <pcoustillas@1g6.biz> À: "Communication channel for MonetDB users" <users-list@monetdb.org> Envoyé: Mardi 9 Décembre 2014 08:16:46 Objet: speed query with 2 columns group by Hello, I have an query with the same source data on Jan2014 -SP3 version of monetddb and Oct2014 - SP1 : CREATE TABLE tmp __pierre5 AS ( SELECT id_unique, Device , COUNT (*) AS NBVISISTES FROM donnees_lmd_pierre GROUP BY id_unique, Device ) WITH DATA; On version Jan2014 -SP3 : Welcome to mclient , the MonetDB / SQL interactive terminal (Jan2014-SP3) Database : MonetDB v11.17.21 (Jan2014-SP3), 'mapi : monetdb :// lemondedev :50000/ lemonde' Type \q to quit , \? for a list of available commands auto commit mode: on sql > CREATE TABLE tmp __pierre5 AS ( SELECT id_unique, Device , COUNT (*) AS NBVISISTES FROM donnees _ lmd _pierre GROUP BY id_unique, Device ) WITH DATA; operation successful (6m 30s) On version Oct2014-SP1 : Welcome to mclient , the MonetDB / SQL interactive terminal (Oct2014-SP1) Database : MonetDB v11.19.7 (Oct2014-SP1), 'mapi : monetdb :// monetdb :50000/ lemonde' Type \q to quit , \? for a list of available commands auto commit mode: on sql > CREATE TABLE tmp __pierre5 AS ( SELECT id_unique, Device , COUNT (*) AS NBVISISTES FROM donnees _ lmd _pierre GROUP BY id_unique, Device ) WITH DATA; operation successful (383m 20s) explain query is different , you want to explain the results of the query ? Pierre -- 1G6 52 route de bischwiller 67300 Schiltigheim Société de Services et de Formations en Logiciels Libres http://1g6.biz Tél : 06 64 63 70 35 _______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list