PEP 249 (database api) -- executemany() with iterable?

[Jon Clements]

On 12 Oct, 18:32, Roy Smith <r... at panix.com> wrote:
> On Oct 12, 1:20 pm, Jon Clements <jon... at googlemail.com> wrote:
>
> > On 12 Oct, 16:10, Roy Smith <r... at panix.com> wrote:
>
> > > PEP 249 says about executemany():
>
> > >         Prepare a database operation (query or command) and then
> > >         execute it against all parameter sequences or mappings
> > >         found in the sequence seq_of_parameters.
>
> > > are there any plans to update the api to allow an iterable instead of
> > > a sequence?
>
> > I'm not understanding (probably me). Example?
>
> I have a dictionary, d, which has a million items in it, and want to
> do something like:
>
>     executemany("update foo set bar = %s where id = %s",
> d.iteritems())
>
> If executemany accepted an iterable, that would work.  But, it only
> accepts a sequence, so I need to do:
>
>     executemany("update foo set bar = %s where id = %s", d.items())
>
> which generates a million-item temporary list.  Or am I mis-
> understanding the PEP?

Interesting, but here's my guess...

Replace d.items() with itertools.repeat( ('a', 'b') )

So, if you have a sequence, which has a length and known size, at
least you can have an attempt at the DB operations: whether the
transaction fails or not is another thing...In short, a sequence is
finite, while an iterable may be infinite.

That's just my guess and makes sense to me at least!

Jon.