On Thu, Aug 30, 2007 at 03:32:40PM -0400, Tom Lane wrote:
> difference is that SERIALIZABLE takes one snapshot at transaction start
> and works with that for the whole transaction, whereas READ COMMITTED
> takes a new snap for each statement.
Oh, I get it. This explains then why in principle READ COMMITTED
oughta be faster in the absence of conflicts: additional snapshot
checks are not needed? (Sorry to be obtuse. I think I had a
backward mental picture of how this worked: like SERIALIZABLE did
everything RC did, and then threw stuff away, or in any case did
additional work to ensure a nearly-mathematical serializability.)
A
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