I have a table to which i bulk load datasets of about up to 20,000 rows at a time. It has a primary key, plus a dataset id (bioassay_id), however i just ran this query: bugasbase2=# SELECT bioassay_id, count(*) from mba_data_base where bioassay_id = 5153 group by bioassay_id; bioassay_id | count -------------+------- 5153 | 20000 9712 | 120 bugasbase2=# SELECT bioassay_id, count(*) from mba_data_base where bioassay_id = 9712 group by bioassay_id; bioassay_id | count -------------+------- 9712 | 4624 any ideas why bioassay_id 9712 appears in the first query?? does this suggest corruption somewhere? thanks for any help adam -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.