At 11:08 AM 1/6/00 -0500, Bruce Momjian wrote:
>
>> 4/ Informix outer join syntax
>> o informix uses outer joins of the form
>> SELECT * FROM a, outer b where a.nr = b.nr
>> This will require some post-processing to determine
>> the actual join conditions.
>
>Believe it or not, I am hoping to get this into 7.0. The ANSI syntax
>requires a lot of optimizer changes, because it basically allows user
>specification of the join order. In talking to Thomas, we hoped to
>implement OUTER as a flag on the table that we could easily implement in
>7.0. Let's see how it goes.
Hmmm...I have to question this wisdom of this, because once in and
used there will be pressure to support it forever. How will this
play with the SQL 92 syntax? Order specification isn't a bad thing
given the fact that outer joins aren't associative (SQL for smarties
gives examples).
I've been wanting outer joins, but in my porting efforts have managed
to work around them without too much difficulty, even though 6.5's
limitations on subselects (not in target lists) requires that I
create PL/pgSQL functions in some cases.
I certainly can't speak for the majority of users, but as one data
point I'd personally rather see outer joins done right (SQL 92
syntax) and wait a bit.
Then again, I tend to be a bit of a language purist...
- Don Baccus, Portland OR <dhogaza@pacifier.com> Nature photos, on-line guides, Pacific Northwest Rare Bird Alert
Serviceand other goodies at http://donb.photo.net.
