The following bug has been logged online:

Bug reference: 1326
Logged by: Fernando Kasten Peinado

Email address: fernandopeinado (AT) uol (DOT) com.br

PostgreSQL version: 7.4.5

Operating system: Linux RedHat 7.3

Description: Unique and Primary Key index over bigint type doesn't
work

Details:

index is not used when Type is bigint.


sislu=> \d x
Table "public.x"
Column | Type | Modifiers
--------+------------------------+-----------
id | bigint | not null
name | character varying(100) |
age | integer |
bigid | bigint |
Indexes:
"x_pkey" primary key, btree (id)
"un_x_age" unique, btree (age)
"un_x_bigid" unique, btree (bigid)
"un_x_name" unique, btree (name)

sislu=> explain select * from x where x.id = 12345;
QUERY PLAN
---------------------------------------------------
Seq Scan on x (cost=0.00..22.50 rows=2 width=88)
Filter: (id = 12345)
(2 rows)

sislu=> explain select * from x where x.bigid = 12345;
QUERY PLAN
---------------------------------------------------
Seq Scan on x (cost=0.00..22.50 rows=2 width=88)
Filter: (bigid = 12345)
(2 rows)

sislu=> explain select * from x where x.name = 'asdf';
QUERY PLAN
--------------------------------------------------------------------
Index Scan using un_x_name on x (cost=0.00..4.82 rows=2 width=88)
Index Cond: ((name)::text = 'asdf'::text)
(2 rows)

sislu=> explain select * from x where x.age = 1;
QUERY PLAN
-------------------------------------------------------------------
Index Scan using un_x_age on x (cost=0.00..4.82 rows=2 width=88)
Index Cond: (age = 1)
(2 rows)



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PostgreSQL Bugs List wrote:
This is a known issue with versions prior to 8.0. When you provide a
constant integer smaller than 2^31 it assumes you want int4. Of course,
the planner then looks for an int4 index and can't find one.

The solution/workaround is to make sure you specify the type of your
constant, or at least make sure it doesn't look like an int4.
select * from x where x.id = 12345::int8;
select * from x where x.id = CAST(12345 AS int8);
select * from x where x.id = '12345';

The last works because '...' is type unknown so it looks at x.id to see
what type it wants and casts for you.

HTH

--
Richard Huxton
Archonet Ltd

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