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* Discovering the class from an object identifier
@ 1994-05-11 22:59 Aaron Roydhouse <Aaron.Roydhouse@Comp.VUW.AC.NZ>
0 siblings, 1 reply; 2+ messages in thread
From: Aaron Roydhouse @ 1994-05-11 22:59 UTC (permalink / raw)
To: legacy
I'm not sure how to approach this problem, maybe I'm hoping for too
much.
Given the oid of an instance, how can I discover the most specific
class the instance belongs to?
Alternatively, how can I retrieve an instance identified by an oid,
which knowing the classes it belongs to?
Consider this toy example...
* create EMP (name = text, salary = int4,
age = int4, dept = char16)
\g
Query sent to backend is "create EMP (name = text, salary = int4, age = int4, dept = char16) "
CREATE
Go
* append EMP (name = "Claire", salary = 2000,
age = 40, dept = "shoe")
\g
Query sent to backend is "append EMP (name = "Claire", salary = 2000, age = 40, dept = "shoe") "
APPEND 656830
Go
* create STUD_EMP (location = point) inherits (EMP)
\g
Query sent to backend is "create STUD_EMP (location = point) inherits (EMP) "
CREATE
Go
* append STUD_EMP (name = "Sunita", salary = 4000,
age = 23, dept = "electronics",
location = "(3, 5)")
\g
Query sent to backend is "append STUD_EMP (name = "Sunita", salary = 4000, age = 23, dept = "electronics", location = "(3, 5)") "
APPEND 656908
Go
So given "656908"::oid how can I detemine whether it identifies a
STUD_EMP or just an EMP?
I've obviously trying to avoid querying every class in hope.
Aaron.
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^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Discovering the class from an object identifier
@ 1994-05-12 02:16 Paul M. Aoki <aoki@postgres.Berkeley.EDU>
parent: Aaron Roydhouse <Aaron.Roydhouse@Comp.VUW.AC.NZ>
0 siblings, 0 replies; 2+ messages in thread
From: Paul M. Aoki @ 1994-05-12 02:16 UTC (permalink / raw)
To: Aaron Roydhouse <Aaron.Roydhouse@Comp.VUW.AC.NZ>; +Cc: legacy
Aaron Roydhouse <Aaron.Roydhouse@Comp.VUW.AC.NZ> writes:
> Given the oid of an instance, how can I discover the most specific
> class the instance belongs to?
> Alternatively, how can I retrieve an instance identified by an oid,
> which knowing the classes it belongs to?
> I've obviously trying to avoid querying every class in hope.
the commercial derivative of postgres splits oids into a class
identifier and an instance identifier, but postgres itself just
assigned oids sequentially in a given database.
--
Paul M. Aoki | CS Div., Dept. of EECS, UCB | aoki@postgres.Berkeley.EDU
| Berkeley, CA 94720 | ...!uunet!ucbvax!aoki
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1994-05-11 22:59 Discovering the class from an object identifier Aaron Roydhouse <Aaron.Roydhouse@Comp.VUW.AC.NZ>
1994-05-12 02:16 ` Paul M. Aoki <aoki@postgres.Berkeley.EDU>
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