On Jun 11, 2014, at 8:11 AM, Wolfgang Leimer <[email protected]> wrote:
>
> Hi Quincey,
>
> now I create the objects with both flags, but our tests show that
> H5Aopen_by_idx() is still 2x slower than H5Aopen_by_name().
Well, at least that's a 15x improvement. :-) Still, I wouldn't think
that it should be 2x slower, since it's the same basic code. Can you write a
short standalone C program that demonstrates the timing difference?
Quincey
> lg
> Wolfgang
>
> On 2014-05-30 00:01, Quincey Koziol wrote:
>> Hi Werner,
>> On May 21, 2014, at 6:23 AM, Werner Benger <[email protected]> wrote:
>>> What is the quickest way to open attributes in a callback from
>>> H5Aiterate2() ?
>>> It would seem that in the callback function there is the option to
>>> either call
>>> H5Aopen_by_idx() or H5Aopen_by_name() .
>>> Since the callback function receives an _H5A_info_t_ a [1]s
>>> parameter, one might
>>> expect that using its corder member to open the attribute by index
>>> would be
>>> faster than going via another name lookup. However, our experiments
>>> it is
>>> 30x slower to go via the index than via the name.
>>> Is this expected behavior? Are the alternatives?
>> Hmm, did you create the object with the "index the creation order
>> info" flag as well as the "track the creation order info" flag?
>> Quincey
>> Links:
>> ------
>> [1] http://www.hdfgroup.org/HDF5/doc/RM/RM_H5A.html#Annot-OpenByIdx
>
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