Template:FAQ:Coding 16

The first thing to realise is that the 'get_first' and 'get_next' hook routines are concerned with processing a single SNMP request, not with walking the whole table. A full "snmpwalk" command will typically involve a series of individual 'GetNext' requests, and every one of these will trigger a separate 'get_first/get_next/get_next/....' cycle.

It's usually more efficient to use 'snmptable' which will walk each column in parallel (as well as displaying the results in a more natural manner).

Secondly, the iterator helper was originally designed to handle unsorted data, so will look at every row of the internal table for each request. If the data is actually held in the correct order, then it's worth setting the NETSNMP_ITERATOR_FLAG_SORTED flag:

  iinfo = SNMP_MALLOC_TYPEDEF(netsnmp_iterator_info);
  iinfo->flags |= NETSNMP_ITERATOR_FLAG_SORTED;

This will help the situation somewhat.

But the iterator helper is inherently a relatively inefficient mechanism, and it may be worth looking at one of the other helpers, particularly if the data will be held within the agent itself.