From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Mike Fowler <mike(at)mlfowler(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Adding XMLEXISTS to the grammar |
Date: | 2010-06-09 17:21:56 |
Message-ID: | 27652.1276104116@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Look at how the POSITION() pseudofunction is defined around gram.y
> line 9651. Essentially any special syntax of this type gets converted
> to a regular function call internally. So in your case I think there
> will be some function that gets called something ike this:
> xmlexists(xpath_expression, xml_expression)
> ...but the grammar can be modified to allow a different syntax for
> that function call.
Note also that we typically try to allow the function to be called with
the generic comma-separated syntax as well as the keyword-based syntax
that the SQL committee has such weird love for. This makes life easier
for users, and it also means that we don't need special cases in
ruleutils.c.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Kris Jurka | 2010-06-09 17:28:15 | Re: [BUGS] Server crash while trying to read expression using pg_get_expr() |
Previous Message | Tom Lane | 2010-06-09 17:18:18 | Re: Idea for getting rid of VACUUM FREEZE on cold pages |