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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ron Johnson <ronljohnsonjr@gmail.com>
cc: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
Subject: Re: Repeatable Read Isolation Level "transaction start time"
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Comments: In-reply-to Ron Johnson <ronljohnsonjr@gmail.com>
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Ron Johnson <ronljohnsonjr@gmail.com> writes:
> But why does "SELECT 1;" need a snapshot?  Heck, why does "SELECT
> <immutable>;" need a snapshot?

Because we're not going to analyze the statement in the amount of
depth needed to make that distinction before we crank up the
transactional machinery.  If it says SELECT, it gets a snapshot.

			regards, tom lane