bug in hash indexes???

hi,
i observed strange behavior using hash index. is it a known bug?

the index was created before loading data into table. when i recreate the
tc01_tc01pk____idx index everything is ok.

and i can see some other strange things with hash indexes in other tables.
is it possible that i'm using hash indexes in a bad way? or is it because
of using multiple indexes on one column?

any ideas?

thanks,
kuba


db_c01=# select version();
                            version
---------------------------------------------------------------
 PostgreSQL 7.1.2 on i686-pc-linux-gnu, compiled by GCC 2.95.4

-- running debian, kernel 2.4, installed from .deb package


db_c01=# \d tc01
                                        Table "tc01"
 Attribute |         Type          |                        Modifier
-----------+-----------------------+--------------------------------------------------------
 tc01pk___ | integer               | not null default
nextval('"tc01_tc01pk____seq"'::text)
 tc01mobil | character varying(30) | not null
 tc01jmeno | character varying(50) |
 tc01prijm | character varying(50) |
 tc01zusta | double precision      | not null
 tc03pk___ | integer               | not null
 tc01akt__ | boolean               | not null default 't'::bool
Indices: tc01_pkey,
         tc01_tc01pk____idx,
         tc01_tc01prijm_idx

-- tc01_tc01pk is a hash index on tc01pk___
-- tc01_pkey is a btree index on tc01pk___

db_c01=# explain select oid, * from tc01 order by tc01pk___ desc LIMIT 1;
Limit  (cost=0.00..0.06 rows=1 width=57)
  ->  Index Scan Backward using tc01_pkey on tc01  (cost=0.00..59.00
rows=1000 width=57)

db_c01=# select oid, * from tc01 order by tc01pk___ desc LIMIT 1;
   oid   | tc01pk___ | tc01mobil  | tc01jmeno | tc01prijm | tc01zusta |
tc03pk__
---------+-----------+------------+-----------+-----------+-----------+---------
 1469963 |     10003 | 0609123456 | pepa      | vomacka   |     10000 |
(1 row)


db_c01=# explain select oid, * from tc01 where tc01pk___ = 10003;
Index Scan using tc01_tc01pk____idx on tc01  (cost=0.00..8.14 rows=10
width=57)

db_c01=# select oid, * from tc01 where tc01pk___ = 10003;
 oid | tc01pk___ | tc01mobil | tc01jmeno | tc01prijm | tc01zusta |
tc03pk___ | t
-----+-----------+-----------+-----------+-----------+-----------+-----------+--
(0 rows)