Re: Revisited: Transactions, insert unique.

Today, in a message to pgsql-general, Ross J. Reedstrom wrote:
>
> I see you haven't done much Language Lawyering, have you?

No, and I have no intention of getting into it now :-)

> There is no such thing as the 'spirit' of the standard, only the
> written document. ;-)

The spirit of the standard comes into play when people who are not
Language Lawyers try to decide how something should work that is not
spelled out explicitly, but where the standard text contains suggestive
statements that imply that the authors assumed something without spelling
it out, because they thought everybody reading the standard would agree on
this as a matter of course. Of course, as soon as somebody comes along who
has some motivation to make a contrary assumption, perhaps to claim
compliance, the fact that the assumption was not spelled out leads to the
kinds of arguments we are having.

> This is exactly my argument, with regard to errors and the standard:
> _which_ errors are considered unrecoverable is not spelled out in the
> standard, therefore, it is implementation defined. The fact the the
> definition chosen by postgresql is inconvenient for users of the database
> is, I agree, unfortunate, but it doesn't stand in the way of us claiming
> compliance, which is the name of the game for these sort of standards.

This is precisely NOT the game I'm playing! I don't care whether something
is technically 100% compliant or not. I do care a lot about improving a
free software database management system that is in the same league as the
big-name databases.

The reason I entered this discussion was not to discuss whether postgresql
is or is not 100% compliant with SQL92. Supporting statement level aborts
is a feature that should be supported at some point, and this talk about
the current practice somehow being compliant with the letter of the
standard doesn't help.

> Note that postgres is careful not to _automatically_ rollback: the
> standard (as you quoted) indicated only certain conditions that allow for
> an implicit rollback of that sort.

The standard is very explicit about some types of errors, namely
constraint violations, where it says that this must have no effect except
an entry in the diagnostics area. It is precisely these errors where one
would like to be able to continue the transaction.

Joachim

--
private: joachim(at)kraut(dot)bc(dot)ca (http://www.kraut.bc.ca)
work: joachim(at)mercury(dot)bc(dot)ca (http://www.mercury.bc.ca)