Postgresql JDBC process consumes more memory than psql client

[James Pang (chaolpan)]

  We run same update or delete SQL statement " DELETE FROM ... WHERE ... "  the 
table is a hash partition table (256 hash partitions). When run the sql from 
Postgresql JDBC driver, it soon increased to 150MB memory (RES filed from top 
command),       but when run the same SQL from psql , it only consumes about 
10MB memory.  UPDATE statements is similar , need 100MB memory, even it delete 
or update 0 rows.  Any specific control about Postgresql JDBC driver ?

Thanks,

James