Re: Question about SSI, subxacts, and aborted read-only xacts

On Sun, Sep 16, 2012 at 04:16:22PM -0500, Kevin Grittner wrote:
> I'm attaching an alternative proposal, with changes for the following
> reasons:
>
> (1) The complete re-wrap of that first paragraph made it really hard
> to see what the actual change to the documentation was. I would
> rather change it like this and have a separate patch to re-wrap the
> paragraph (with no content change) or maybe restrict the reformatting
> to two or three lines.
>
> (2) The second paragraph starts with "There may still be
> serialization anomalies involving aborted transactions" which seems
> a bit alarming, seems to bend the definition of serialization
> anomalies and seems odd to pick out for special attention when the
> same could be said of data read in transactions at other isolation
> levels if those transactions roll back from a deferred constraint or
> a write conflict.
>
> (3) There is a significant exception to this caveat which I felt
> would be useful to people who wanted to generate big reports without
> waiting for transaction commit: deferrable read-only transactions
> offer applications a way to count on data as soon as it is read.
>
> I'm not sure whether the omission of this from the docs should be
> considered a big enough hazard to merit a back-patch, or if it should
> just be committed to HEAD.

Patch applied to git head.

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

+ It's impossible for everything to be true. +