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Greg
On 28 May 2009, at 02:49, Tom Lane <t...@sss.pgh.pa.us> wrote:
Greg Stark <greg.st...@enterprisedb.com> writes:
Without any real way to represent predicates this is all pie in the
sky. The reason we don't have predicate locking is because of this
problem which it sounds like we're no closer to solving.
Yeah. The fundamental problem with all the "practical" approaches
I've
heard of is that they only work for a subset of possible predicates
(possible WHERE clauses). The idea that you get true serializability
only if your queries are phrased just so is ... icky. So icky that
it doesn't sound like an improvement over what we have.
I think you get "true serializability" in the sense that you take out
a full table lock on every read. I.e. Your transactions end up
actually serialized... Well it would be a bit weaker than that due to
the weak read-locks but basically you would get random spurious
serialization failures which can't be explained by inspecting the
transactions without understanding the implementation.
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