Re: Nested Transactions, Abort All - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: Nested Transactions, Abort All
Date
Msg-id 20040706155630.GC8235@dcc.uchile.cl
Whole thread Raw
In response to Re: Nested Transactions, Abort All  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
On Tue, Jul 06, 2004 at 11:37:18AM -0400, Bruce Momjian wrote:
> Alvaro Herrera wrote:
> > On Sat, Jul 03, 2004 at 02:32:44AM -0500, Thomas Swan wrote:
> > > Alvaro Herrera wrote:
> > 
> > > >What I'd like to do is start the transaction block before the function
> > > >is called if we are not in a transaction block.  This would mean that
> > > >when the function calls BEGIN it won't be the first one -- it will
> > > >actually start a subtransaction and will be able to end it without harm.
> > > >I think this can be done automatically at the SPI level.
> > >
> > > Please tell me there is some sanity in this.   If I follow you
> > > correctly, at no point should anyone be able to issue an explicit
> > > begin/end because they are already in an explicit/implicit transaction
> > > by default...  How is the user/programmer to know when this is the case?
> > 
> > I'm not sure I understand you.  Of course you can issue begin/end.  What
> > you can't do is issue begin/end inside a function -- you always use
> > subbegin/subcommit in that case.
> 
> And if you use SUBBEGIN/SUBCOMMIT in a function that isn't already call
> inside from an explicit transaction, it will work because the call
> itself is its own implicit transaction, right?

Right.  Note that this doesn't work with the current code -- in fact you
can cause a server crash easily.

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Doing what he did amounts to sticking his fingers under the hood of the
implementation; if he gets his fingers burnt, it's his problem."  (Tom Lane)



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