TM::Index::Match(3) Topic Maps, Indexing support (match layer)


# somehow get a map (any subclass of TM will do)
my $tm = ...
# one option: create a lazy index which learns as you go
use TM::Index::Match;
my $idx = new TM::Index::Match ($tm);

# for most operations which involve match_forall to be called
# reading and querying the map should be much faster
# learn about some statistics, what keys are most likely to be useful
my @optimized_keys = @{ $stats->{proposed_keys} };
# another option: create an eager index
my $idx = new TM::Index::Match ($tm, closed => 1);
# pre-populate it, use the proposed keys
$idx->populate (@optimized_keys);
# this may be a lengthy operation if the map is big
# but then the index is 'complete'
# query map now, should also be faster
# getting rid of an index explicitly
# cleaning an index


This index implements a generic query cache which can capture all queries not handled by more specific indices. This class inherits directly from TM::Index.



The constructor/destructors are the same as that described in TM::Index.


$idx->populate (@list_of_keys)

To populate the index with canned results this method can be invoked. At this stage it is not very clever and may take quite some time to work its way through a larger map. This is most likely something to be done in the background.

The list of keys to be passed in is a bit black magic. Your current best bet is to look at the index statistics method, and retrieve a proposed list from there:

   @optimized_keys = @{ $stats->{proposed_keys} };
   $idx->populate (@optimized_keys[0..2]); # only take the first few

If this list is empty, nothing clever will happen.

$hashref = $idx->statistics

This returns a hash containing statistical information about certain keys, how much data is behind them, how often they are used when adding information to the index, how often data is read out successfully. The "cost" component can give you an estimated about the cost/benefit.


Copyright 200[6] by Robert Barta, <[email protected]>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.