Thank you for your reply. qis3_dp2=> SHOW lc_collate; lc_collate ------------- en_US.UTF-8 (1 row) Time: 0.311 ms qis3_dp2=> qis3_dp2=> SELECT COUNT(DISTINCT SVIN) AS CHECKCARNUM ,SMTOC FROM QIS_CARPASSEDSTATION A WHERE 1=1 AND A.SSTATIONCD = 'VQ3_LYG' AND A.SLINYYY-MM-DD') AND A.DWORKDATE <= TO_DATE('2019-03-11','YYYY-MM-DD') group by SMTOC ; checkcarnum | smtoc -------------+----------------------- 90 | HT6LHD700 NH731P A 690 | HT6LHD700 NH788P A 90 | HT6LHD700 R550P A 30 | HT6LHD700 YR615M A 1141 | HT6MHB700 NH731P A Is there any possibility of optimization? -- Sent from: http://www.postgresql-archive.org/PostgreSQL-performance-f2050081.html