>>> Tom Lane <t...@sss.pgh.pa.us> wrote: > Jeff Davis <pg...@j-davis.com> writes: >> There you see a snapshot of the table that never existed. Either the >> snapshot was taken before the UPDATE, in which case i=3 should be >> included, or it was taken after the UPDATE, in which case i=4 should be >> included. So atomicity is broken for WHERE. > > This assertion is based on a misunderstanding of what FOR UPDATE in > read-committed mode is defined to do. It is supposed to give you the > latest available rows. Well, technically it's violating the Isolation part of ACID, not the Atomicity, since the UPDATE transaction will either commit or roll back in its entirety, but another transaction can see it in an intermediate (partially applied) state.[1] I guess the issue of whether this violation of ACID properties should be considered a bug or a feature is a separate discussion, but calling it a feature seems like a hard sell to me. -Kevin [1] http://en.wikipedia.org/wiki/ACID
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