Re: [cx-oracle-users] Positional parameters, REF's, BINARY_FLOAT and BINARY_DOUBLE

[Anthony T. <an...@co...>]

On Wed, 2004-03-03 at 04:28, Danny R. Boxhoorn wrote:
> There are many reason to switch from DCOracle2 to cx_Oracle and there are a
> few that keep me from switching.
> The most important one is that lack of support for positional parameters.
> I.e., you cannot do something like
> 
>   cursor.execute('select 4 from dual where :1 > 1', 37)
> 
> which DCOracle2 allows you to do.
> A workaround is to use named parameters and replace all the occurrences of
> :<n> with :p<n> in queries. Given the heavy use of positional parameters in the code I have I would like to avoid rewriting it.
> So the questions are:
> Is support for positional parameters planned?

Yes. Interestingly enough I have had some discussions with another
person off the list regarding this very same thing. I ran a few tests
and creating lists is twice as fast as creating dictionaries so
performance wise it is a worthwhile addition. Besides which, sometimes
it is quite convenient to be able to use positional parameters, such as
in callproc() and callfunc() where currently I have to transform the
list into a dictionary in order to call execute(). So yes, I was leaning
towards adding this in 4.1.

> How much work would be needed to support positional parameters?

That depends on the answers to a couple of questions. In the above code
you specify a parameter not inside a list. Does that mean DCOracle2 has
the following syntax (Python equivalent)

def execute(sql, *args) # where args is all positional parameters

OR 

def execute(sql, args) # where args is a list

I personally prefer the first but the DB API indicates that the latter
is a requirement. If I continue to use the latter, then all I have to do
is check to see if the arguments passed are a list or a dictionary and
act accordingly. The rest is fairly straightforward. If you were hoping
for the former, then I'd like some answers as to how to make it
compatible with the DB API. One possibility is to check to see if only
one parameter is passed and if it is a list of dictionary, do the DB API
thing; otherwise, take the entire list and pass it through as positional
parameters. It smacks of hacking but I can't thing of anything else. Any
ideas?

BTW, does DCOracle2 supported named parameters as well? Do you know or
should I just go look at the source and see what they do? :-)

> Another question is about object REFerences. It would be nice if they
> would be supported. DCOracle2 support for them is limited to `Segmentation
> Fault'. I already had a look and I think I could add support for REF's
> myself. But before I do that I would like to know whether that's appreciated
> and, more importantly, needed ... is support for REF's planned? [)

I have never had occasion to use Oracle "objects" (named types) so I
haven't bothered adding support. I don't see that changing soon so
although I would be interested in having support added, it isn't high on
my priority list at the moment. If you are willing to provide patches, I
am willing to add them and I would be very appreciative. :-)

> Finally, what about the new BINARY_FLOAT and BINARY_DOUBLE types in 10g.
> They are high on my wishlist and I can imagine it's trivial to add support
> for them. Again, is this planned?

I have just barely looked at 10g so I hadn't really planned anything on
that front yet. I know that cx_Oracle compiles and passes the test suite
on 10g on Linux but nothing more than that yet. Still, I do remember
reading about these in the release notes and I can't see that they would
be a problem. So yes, I will definitely add these as soon as I can get
some more time to play with 10g.

> Thanks for the hard work and the prompt and polite response,

You're welcome.

>                                                    Danny R. Boxhoorn
> 
> Kapteyn Institute / OmegaCEN               e-mail: da...@as...
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-- 
Anthony Tuininga
an...@co...
 
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