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Re: age(xid) function bug

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: age(xid) function bug
Date: 2008-08-20 04:06:40
Message-ID: 200808200406.m7K46eb01937@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > However, the function only does a subtraction with no adjustment for
> > overflow, and considering it returns a signed int, it can't even display
> > the full range of valid values:
> 
> Say again?  The possible range of ages is only 2 billion.

If we assume that only xid stored in actual tables are used, yes:

	test=> select txid_current();
	 txid_current
	--------------
	          402
	(1 row)
	
	test=> select age('4294967290'::xid);
	 age
	-----
	 409
	(1 row)

OK, so it does work based on the limitations we place on stored xids.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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