Hi Michal,
You can test the code in the latest SNMP4J 2.4.0 SNAPSHOT that built a
few minutes ago:
https://oosnmp.net/dist/snapshot/org/snmp4j/snmp4j/2.4.0-SNAPSHOT/
The optimized algorithm seems to be significantly faster for nearly any
sparse table, especially
if one reduces the max-repetitions to a lower value than the average
number of missing values in a
column.
Best regards,
Frank
Am 07.12.2015 um 14:20 schrieb Michał Steiner:
Great! I can be first to test it.
I agree that improvement will be visible only in specific cases. We
have a tables with almost 200 columns where some of them are full,
some are empty or have just couple of cells with value. So in our case
it could be huge improvement.
--
Michal
2015-12-07 12:35 GMT+01:00 Frank Fock <[email protected]
<mailto:[email protected]>>:
Hi Michal,
The proposed improvement can be indeed applied to any column,
but will have an effect only if the a lot of cells are missing and
the distribution is asymmetric.
I will try to implement the improvement for SNMP4J 2.4.0
Best regards
Frank
> Am 02.12.2015 um 09:19 schrieb Michał Steiner <[email protected]
<mailto:[email protected]>>:
>
> Hi,
>
> I've noticed that getTable method in org.snmp4j.util.TableUtils
could be
> more efficient for sparse tables.
>
> Consider table with 3 columns and 3 rows, but in first column
there is a
> lot of empty cells:
>
> Column1 Column2 Column3
> value-1-1 value-2-1 value-3-1
> <empty> value-2-2 value-3-2
> <empty> value-2-3 value-3-3
>
> Today implementation works more or less like this:
>
> get-next Column1 Column2 Column3
> response value-1-1 value-2-1 value-3-1
>
> get-next value-1-1 value-2-1 value-3-1
> response value-2-1 value-2-2 value-3-2
>
> get-next value-1-1 value-2-2 value-3-2
> response value-2-1 value-2-3 value-3-3
>
> get-next value-1-1 value-2-3 value-3-3
> response value-2-1 value-3-3 value from next table
>
>
> As you can see request for value-1-1 is done 3 times and
only first
> one makes sense.
> This is an issue for large tables (lot of columns and rows)
with many
> empty cells.
> This algorithm can be improved. After first response from other
column we
> can just stop asking about it. Conversation will look like this:
>
>
> get-next Column1 Column2 Column3
> response value-1-1 value-2-1 value-3-1
>
> get-next value-1-1 value-2-1 value-3-1
> response value-2-1 value-2-2 value-3-2 <-- value-2-1
is from
> different column
>
> get-next value-2-2 value-3-2 <-- in next
requests we
> skip first column
> response value-2-3 value-3-3
>
> get-next value-2-3 value-3-3
> response value-3-3 value from next table
>
> I guess that bulk request are handled in the similar way, aren't
they ?
>
> Are my observations correct ?
> What do you think about such improvement?
>
>
> Regards
>
> Michal
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