Re: oid's and primary keys on insert

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От Joe Conway
Тема Re: oid's and primary keys on insert
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Msg-id 3D543155.1060909@joeconway.com
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Ответ на oid's and primary keys on insert  (Rob Brown-Bayliss <rob@zoism.org>)
Список pgsql-general
Rob Brown-Bayliss wrote:
> On Sat, 2002-08-10 at 08:34, Andrew Sullivan wrote:
>
>>On Sat, Aug 10, 2002 at 08:32:39AM +1200, Rob Brown-Bayliss wrote:
>>
>>
>>>Why are the developers (maybe) getting rid of OID's?  Wont they then
>>>have to come up with another way of identifiying data inside postgresql?
>>
>>They already have.  OIDs won't go away for everything, just on a
>>table, if you created the table that way.
>
>
> I thought there is a possibility that even that will disappear?
>
> Are OID's created by default at the moment?
>

I don't think they will disappear, but in some future release they may
not be created by default for user tables (they are created by default
in current development sources, IIRC). They are still, and will most
likely will continue to, be used for certain system tables.

There is at least one good reason to not create oids on user tables:
since they are generated from one source for the entire PostgreSQL
cluster, in a large installation they can roll-over at 4 billion. By
using them for system tables only, the concern of roll-over effectively
goes away.

There have been discussions of making per table oid generators but it
doesn't look like that will happen for 7.3. I think going to 8 byte oids
has been rejected to due to the performance hit and additional per row
overhead.

Joe


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