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Hi guys,
I have a question about pg_cast--- data type
convert.
Pg provide more data types than sql spec, such as
OID.
Internal OID type is unsigned int32 and
INT8 is int64.
Why pg can convert INT8 into OID implicitly
while can not convert OID into INT8 implicitly?
There may be some problems
when using coalesce expr. Have a look at the following case:
postgres=# create table test1(c1 OID, c2
BIGINT);
CREATE TABLE postgres=# create view v1 as select coalesce(c1,c2) from test1; CREATE VIEW postgres=# \d v1 View "public.v1" Column | Type | Modifiers ----------+------+----------- coalesce | oid | View definition: SELECT COALESCE(test1.c1, test1.c2::oid) AS "coalesce" FROM test1; postgres=# insert into test1(c2) values(-1);
INSERT 0 1 postgres=# select * from v1; ERROR: OID out of range Although we can define the view v1 successfully, but we
can not get what we want.
If pg can convert
INT8 into OID implicitly, it seems there would not be any
problems.
Regards
-Dongni
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