[Python-Dev] More compact dictionaries with faster iteration

Mark Shannon mark at hotpy.org
Tue Dec 11 01:04:14 CET 2012

On 10/12/12 23:39, Raymond Hettinger wrote:
> On Dec 10, 2012, at 4:06 AM, Mark Shannon <mark at hotpy.org
> <mailto:mark at hotpy.org>> wrote:
>>> Instead, the 24-byte entries should be stored in a
>>> dense table referenced by a sparse table of indices.
>> What minimum size and resizing factor do you propose for the entries
>> array?
> There are many ways to do this.  I don't know which is best.
> The proof-of-concept code uses the existing list resizing logic.
> Another approach is to pre-allocate the two-thirds maximum

What do you mean by maximum?

> (This is simple and fast but gives the smallest space savings.)
> A hybrid approach is to allocate in two steps (1/3 and then 2/3
> if needed).

I think you need to do some more analysis on this. It is possible that 
there is some improvement to be had from your approach, but I don't 
think the improvements will be as large as you have claimed.

I suspect that you may be merely trading performance for reduced memory
use, which can be done much more easily by reducing the minimum size
and increasing the load factor.


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