postgresql creates huge files

SunOS amber 5.7 Generic_106542-07 i86pc i386 i86pc
gcc version 2.95.1 19990816 (release)
PostgreSQL 6.5.2

-rw-------   1 postgres postgres 130449408 Oct 25 01:28 pg_noname.17502.0
-rw-------   1 postgres postgres 88981504 Oct 25 01:31 pg_noname.17579.0
-rw-------   1 postgres postgres 61267968 Oct 25 01:31 pg_noname.17615.0
-rw-------   1 postgres postgres 58712064 Oct 25 01:31 pg_noname.17620.0
-rw-------   1 postgres postgres       0 Oct 25 01:30 pg_noname.17690.0
-rw-------   1 postgres postgres       0 Oct 25 01:30 pg_noname.17696.0
-rw-------   1 postgres postgres 2899968 Oct 25 01:31 pg_noname.17706.0