| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Re: [COMMITTERS] pgsql: Ensure age() returns a stable value rather than the latest value |
| Date: | 2012-05-12 14:55:12 |
| Message-ID: | 6151.1336834512@sss.pgh.pa.us |
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Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> Case (2) is more complex than described. If we use XID always, then
> the so-say stable value could change mid way through a scan when the
> XID is assigned and would provide neither a stable, sensible nor a
> backwards compatible response.
No, that's entirely wrong. The original behavior of the function
for case 2, which I am proposing we revert to, is that it would
forcibly assign an XID when the transaction didn't already have one.
Subsequently, that value would be stable for the duraction of the xact.
regards, tom lane
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