Use itertools.chain to improve get on one2many

The construction of ids2 was quadratic, with this patch it should be linear.

vengfulsquirrel: Can you tell me if you notice any improvement? TIA

[ced, 2010-01-11 17:30:03]

Ok for me

[Ian Wilson, 2010-01-11 19:46:40]

On 2010/01/11 17:30:03, ced wrote:
> Ok for me
The chain function looks very interesting but it seems to take about the same
time as += but now the database times have far surpassed the list operations in
time.  Everything in the loop including += part of the code but excluding the
calls to search takes about .001 seconds where as the calls to search takes
about 5 to 6 seconds.

[ced, 2010-01-11 20:06:22]

On 2010/01/11 19:46:40, Ian Wilson wrote:
> On 2010/01/11 17:30:03, ced wrote:
> > Ok for me
> The chain function looks very interesting but it seems to take about the same
> time as += but now the database times have far surpassed the list operations
in
> time.  Everything in the loop including += part of the code but excluding the
> calls to search takes about .001 seconds where as the calls to search takes
> about 5 to 6 seconds.

As soon as the memory allocation cost low, there will be no visible improvement
I think.

[ced, 2010-01-13 13:24:16]

Still OK.