Re: InitPostgres and flatfiles question - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: InitPostgres and flatfiles question
Date
Msg-id 200701062201.l06M1vJ03895@momjian.us
Whole thread Raw
In response to Re: InitPostgres and flatfiles question  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: InitPostgres and flatfiles question  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Do we need a TODO for this?

---------------------------------------------------------------------------

Tom Lane wrote:
> Markus Schiltknecht <markus@bluegap.ch> 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
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>        choose an index scan if your joining column's datatypes do not
>        match

--  Bruce Momjian   bruce@momjian.us EnterpriseDB    http://www.enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +


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