Simon Riggs wrote:
On Tue, 2005-08-09 at 16:01 +0100, Richard Huxton wrote:

Tom Lane wrote:

What if there aren't any "untouched chunks"?  With only 64K-chunk
granularity, I think you'd hit that condition a lot more than you are
hoping.  Also, this seems to assume uniqueness across all tables in an
entire cluster, which is much more than we want; it makes the 32-bit
size of OIDs significantly more worrisome than when they only need to be
unique within a table.

Can I ask what happens if we end up re-using a recently de-allocated OID? Specifically, can a cached plan (e.g. plpgsql function) end up referring to an object created after it was planned:

CREATE FUNCTION f1()... -- oid=1234
CREATE FUNCTION f2()... -- oid=1235, calls f1() or oid=1234
DROP FUNCTION f1()
CREATE FUNCTION f3()... -- re-uses oid=1234


Possible, but extremely unlikely... you'd have to keep a session open
with a prepared query for as long as it takes to create a 4 billion
tables... not a high priority case, eh?

Ah, but it does rule out the possibility of keeping a cache of "recently de-allocated" OIDs and re-using those.

--
  Richard Huxton
  Archonet Ltd

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