Markus Schiltknecht <[EMAIL PROTECTED]> writes:
> I've just found the stumbling block: the -c option of psql wraps all in 
> a transaction, as man psql says:
> ...
> Thank you for clarification, I wouldn't have expected that (especially 
> because CREATE DATABASE itself says, it cannot be run inside a 
> transaction block... A transaction block (with BEGIN and COMMIT) seems 
> to be more than just a transaction, right?)

Hm, that's an interesting point.  psql's -c just shoves its whole
argument string at the backend in one PQexec(), instead of dividing
at semicolons as psql does with normal input.  And so it winds up as
a single transaction because postgres.c doesn't force a transaction
commit until the end of the querystring.  But that's not a "transaction
block" in the normal sense and so it doesn't trigger the
PreventTransactionChain defense in CREATE DATABASE and elsewhere.

I wonder whether we ought to change that?  The point of
PreventTransactionChain is that we don't want the user rolling back
the statement post-completion, but it seems that
        psql -c 'CREATE DATABASE foo; ABORT; BEGIN; ...'
would bypass the check.

                        regards, tom lane

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