Re: [SQL] maximum number of rows in table - what about oid limits?

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От John Scott
Тема Re: [SQL] maximum number of rows in table - what about oid limits?
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Msg-id 20010606184508.46169.qmail@web10004.mail.yahoo.com
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Ответ на Re: [SQL] maximum number of rows in table - what about oid limits?  (Stephan Szabo <sszabo@megazone23.bigpanda.com>)
Ответы Re: Re: [SQL] maximum number of rows in table - what about oid limits?  (GH <grasshacker@over-yonder.net>)
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well i wasn't interested in using oids in my application.
i was curious about the relationship oids
and the tuple/row limit.

i guess if what you say is true, the oids are NOT used internally
by postgres.  this seems odd.

so, i guess my question still stands ... what happens when oids wrap?
are oids nothing more than a sequence with an index,
not used at all internally?

i
--- Stephan Szabo <sszabo@megazone23.bigpanda.com> wrote:
>
> On 6 Jun 2001, jmscott@REMOVEMEyahoo.com wrote:
>
> > postgresql docs claim an essentially unlimited number of
> > rows per table.
> >
> >    http://postgresql.crimelabs.net/users-lounge/limitations.html
> >
> > this doesn't make sense if each row has an oid.
> > do more subtle side effects exist if the oid wraps?
>
> In general, unless you're relying on unique oids, you should be fine.
> You probably don't want to use oid as a unique key in your tables for that
> reason. Of course, sequences aren't sufficient either (also being
> int4) but some kind of int8 "sequence" mechanism would do it if you expect
> more than the int4 number of rows.
>
> You might have problems with creating system table entries with unique
> oids after wraparound, but generally that can be fixed by trying again.
> (Some of the system tables have a unique index on oid).
>


=====
John Scott (john@august.com)
Senior Partner
August Associates

email: john@august.com
  web: http://www.august.com/~jmscott

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