[ADMIN] Insert statement deletes older table records

[Rabi Jay]

Hi,
 
When I execute an insert statement, older table records are deleted even though 
my insert statement works. It always keeps the maximum number of records in the 
table to 4200 records. So If I added 3 more records, it deletes the first three 
records in the table even though it adds the 3 new records.
 
Based on my research it appears postgreql has no limit to number of records in 
a table - what should I do to avoid this behavior.
 
Thanks.