a problem with index and user define type

Hi all:
I write a use define type (UUID)

typedef struct uuid
{
uint32 time_low;
uint16 time_mid;
uint16 time_hi_and_version;
uint8 clock_seq_hi_and_reserved;
uint8 clock_seq_low;
uint8 node[6];
} uuid;

make all btree index function and operator, such as

CREATE OPERATOR CLASS uuid_btree_ops
DEFAULT FOR TYPE uuid USING btree
AS
OPERATOR 1 < ,
OPERATOR 2 <= ,
OPERATOR 3 = ,
OPERATOR 4 >= ,
OPERATOR 5 > ,
FUNCTION 1 uuid_cmp(uuid, uuid),

create table test_uuid(id uuid primary key default uuid_time(), name
char(40));

but this query: select * from test_uuid where id =
'df2b10aa-a31d-11d7-9867-0050babb6029'::uuid dosn't use index

QUERY PLAN
---------------------------------------------------------------
Seq Scan on test_uuid (cost=0.00..22.50 rows=500 width=140)
Filter: (id = 'df2b10aa-a31d-11d7-9867-0050babb6029'::uuid)

why ??

source code see attachement

MikeWang

---------------------------------------------------------------------
What is uuid?


uuid is a kind of data type, provide for PostgreSQL to implement unique
id in cyberspace,
it's based one UUID URN name space IETF draft (see
doc/draft-mealling-uuid-urn-00.txt),
now, pguuid support NIL(0), Time-Base(1), Name-Base(3) and
Random-Base(4) type UUID.
It's propuse is
provide a solution
for data replication, merge, and distribute.


what is the use of uuid?


1, pguuid provide PostgreSQL a data type: uuid, it can provide unique
id in
cyberspace.
2, provide type uuid related operator (e.g. =, <>, <, >, >=, <=)
3, provide functions to generate Time-base, Name-base, Random-base and
Nil-UUID.
4, provide functions to parse uuid type.

license:
BSD

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