dicts,instances,containers, slotted instances, et cetera.

ocschwar at gmail.com ocschwar at gmail.com
Thu Jan 29 00:23:47 CET 2009


On Jan 28, 5:21 pm, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> ocsch... at gmail.com schrieb:
>
>
>
> > Hi, all.
>
> > I have an application that that creates, manipulates, and finally
> > archives on disk 10^6 instances of an object that in CS/DB terms is
> > best described as a relation.
>
> > It has 8 members, all of them common Python datatypes. 6 of these are
> > set once and then not modified. 2 are modified around 4 times before
> > the instance's archving. Large collections (of small lists) of these
> > objects are created, iterated through, and sorted using any and all of
> > the 8 members as sorting keys.
>
> > It neither has nor needs custom methods.
>
> > I used a simple dictionary to create the application prototype. Now I
> > need to speed things up.
> > I first tried changing to a new style class, with __slots__, __init__,
> > __getstate__& __setstate__ (for pickling) and was shocked to see
> > things SLOW down over dictionaries.
>
> > So of these options, where should I go first to satisfy my need for
> > speed?
>
> > 0. Back to dict
> > 1. old style class
> > 2. new style class
> > 3. new style class, with __slots__, with or without some nuance I'm
> > missing.
> > 4. tuple, with constants to mark the indices
> > 5. namedTuple
> > 6. other...
>
> Use a database? Or *maybe* a C-extension wrapped by ctypes.
>
> Diez

I can't port the entire app to be a stored database procedure.

ctypes, maybe. I just find it odd that there's no quick answer on the
fastest way in Python to implement a mapping in this context.



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