Re: synchronized snapshots

Hi Joachim,

On 14/09/2011 05:37, Joachim Wieland wrote:
> Here is a new version of this patch

In a sequence such as this:
  BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;  INSERT INTO foo VALUES (-1);  SELECT pg_export_snapshot();

the row added to "foo" is not visible in the exported snapshot.  If 
that's the desired behaviour, I think it should be mentioned in the 
documentation.

I can make a patched backend die with an assertion failure by trying to 
export a snapshot after rolling back a transaction which exported a 
snapshot.  Seems like no cleanup is done at transaction abort.

I think that trying to import a snapshot that doesn't exist deserves a 
better error message.  There's currently no way for the user to know 
that the snapshot didn't exist, other than looking at the SQLSTATE 
(22023), and even that doesn't tell me a whole lot without looking at 
the manual.

Finally, the comment in ImportSnapshot() still mentions the old syntax.

Other than these four problems, the patch looks good.


-- 
Marko Tiikkaja                http://www.2ndQuadrant.com/
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