On 4 sep 2014, at 15:32, Pavel Stehule <pavel.stehule@gmail.com> wrote:
2014-09-04 15:24 GMT+02:00 Jan Wieck <jan@wi3ck.info>:
> On 09/04/2014 01:14 AM, Pavel Stehule wrote:
>
>> 2014-09-03 23:19 GMT+02:00 Hannu Krosing <hannu@2ndquadrant.com
>> A more SQL-ish way of doing the same could probably be called COMMAND
>> CONSTRAINTS
>> and look something like this
>>
>> SELECT
>> ...
>> CHECK (ROWCOUNT BETWEEN 0 AND 1);
>>
>>
>> It is very near to my proposed ASSERT
>>
>
> Only if the ASSERT syntax would become part of the original statement, it
> is supposed to check. In Hannu's command constraint example above, the
> statement that causes the error, and thus will be logged and become
> identified by the error message, is the actual SELECT (or other DML
> statement).
>
this is valid argument.
On second hand, I proposed a ASSERT that was not based on expressions only.
There is not a technical issue to write assert with knowledge of related
statement.
>
> I think I like the COMMAND CONSTRAINT the best so far.
>
I not, because when it will not be part of SQL, than parser in plpgsql will
be more complex. You have to inject SELECT, UPDATE, INSERT, DELETE
This is what I suspected. You are against the best syntax because they are
more complex to implement. I think that's coming into the discussion from
the wrong direction. First agree on the best syntax, then worry about the
implementation.
I also understand the syntax changes will mean a lot of trouble for your
plpgsql_check_function() project, but that cannot hold us back, we must aim
for the best possible syntax with plpgsql2.
Your work with plpgsql_check_function() btw saved me hundreds of hours of
work, when we upgraded from 8.4 a few years ago, many thanks Pavel!
Pavel
>
>
> Regards,
> Jan
>
> --
> Jan Wieck
> Senior Software Engineer
> http://slony.info
>
