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# Author : Ulrich Pfeifer |
# Author : Ulrich Pfeifer |
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# Created On : Thu Aug 8 13:05:10 1996 |
# Created On : Thu Aug 8 13:05:10 1996 |
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# Last Modified By: Ulrich Pfeifer |
# Last Modified By: Ulrich Pfeifer |
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# Last Modified On: Tue May 9 08:33:28 2000 |
# Last Modified On: Sat Nov 11 16:32:38 2000 |
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# Language : CPerl |
# Language : CPerl |
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# |
# |
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# (C) Copyright 1996-2000, Ulrich Pfeifer |
# (C) Copyright 1996-2000, Ulrich Pfeifer |
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use Carp; |
use Carp; |
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use vars qw(%FUNC); |
use vars qw(%FUNC); |
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my $O = pack('C', 0xff)."o"; # occurances (document ferquency) |
# The dictionary has three different key types: |
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# 'o'.$word |
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# |
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# The document frequency is the number of documents a term occurs |
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# in. The idea is that a term occuring in a significant part of the |
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# documents is not too significant. |
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# |
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# 'm'.$word |
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# |
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# The maximum term frequency of a document is the frequency of the |
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# most frequent term in the document. It is related to the document |
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# length obviously. A document in which the most frequnet term occurs |
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# 100 times is probably much longer than a document whichs most |
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# frequent term occurs five time. |
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# |
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# 'p'.$word |
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# |
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# Under this key we store the actual posting list as pairs of |
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# packed integers. |
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# The document frequency is the number of documents a term occurs |
my $no_old_index_support = 0; # do not check for old indices if set |
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# in. The idea is that a term occuring in a significant part of the |
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# documents is not too significant. |
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my $M = pack('C', 0xff)."m"; # maxtf (term frequency) |
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# The maximum term frequency of a document is the frequency of the |
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# most frequent term in the document. It is related to the document |
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# length obviously. A document in which the most frequnet term occurs |
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# 100 times is probably much longer than a document whichs most |
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# frequent term occurs five time. |
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sub new { |
sub new { |
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my $type = shift; |
my $type = shift; |
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} |
} |
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} |
} |
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sub is_an_old_index { |
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my $self = shift; |
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return 0 if $no_old_index_support; |
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return $self->{old_index} if exists $self->{old_index}; |
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# We can only guess if this is an old index. We lookup the first 10 |
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# $O entries. If all values are integers, we assume that the index |
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# is an old one. |
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defined $self->{db} or $self->open; |
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$self->sync; |
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my $dbh = $self->{dbh}; # for convenience |
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my $O = pack('C', 0xff)."o"; |
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my ($word, $value) = ($O.$;); |
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$dbh->seq($word, $value, R_CURSOR); |
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for (my $i=0; $i<10;$i++) { |
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if ($value !~ /^\d+$/) { |
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return $self->{old_index} = 0; |
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} |
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if ($dbh->seq($word, $value, R_NEXT) or # no values left |
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$word !~ /^$O/o # no $O values left |
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) { |
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# we are not sure enough that this is an old index |
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return $self->{old_index} = 0; |
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} |
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} |
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return $self->{old_index} = 1; |
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} |
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sub open { |
sub open { |
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my $self = shift; |
my $self = shift; |
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my $file = $self->{file}; |
my $file = $self->{file}; |
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$self->{cdict} = {} |
$self->{cdict} = {} |
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if $self->{mode} & O_RDWR; |
if $self->{mode} & O_RDWR; |
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$self->{cached} = 0; |
$self->{cached} = 0; |
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if (!$no_old_index_support and $self->is_an_old_index()) { |
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warn "This is an old index, upgrade you database"; |
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require WAIT::InvertedIndexOld; |
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bless $self, 'WAIT::InvertedIndexOld'; |
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} |
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} |
} |
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} |
} |
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$self->{records}++; |
$self->{records}++; |
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while (($word, $noc) = each %occ) { |
while (($word, $noc) = each %occ) { |
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if (defined $self->{cache}->{$word}) { |
if (defined $self->{cache}->{$word}) { |
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$self->{cdict}->{$O,$word}++; |
$self->{cdict}->{$word}++; |
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$self->{cache}->{$word} .= pack 'w2', $key, $noc; |
$self->{cache}->{$word} .= pack 'w2', $key, $noc; |
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} else { |
} else { |
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$self->{cdict}->{$O,$word} = 1; |
$self->{cdict}->{$word} = 1; |
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$self->{cache}->{$word} = pack 'w2', $key, $noc; |
$self->{cache}->{$word} = pack 'w2', $key, $noc; |
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} |
} |
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$self->{cached}++; |
$self->{cached}++; |
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for (values %occ) { |
for (values %occ) { |
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$maxtf = $_ if $_ > $maxtf; |
$maxtf = $_ if $_ > $maxtf; |
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} |
} |
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$self->{db}->{$M, $key} = $maxtf; |
$self->{db}->{'m'. $key} = $maxtf; |
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} |
} |
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# We sort postings by increasing max term frequency (~ by increasing |
# We sort postings by increasing max term frequency (~ by increasing |
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# inverse document frequence gives the score for a term. This sort |
# inverse document frequence gives the score for a term. This sort |
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# order can be exploited for tuning of single term queries. |
# order can be exploited for tuning of single term queries. |
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for my $did (sort { $post->{$b} / $self->{db}->{$M, $b} |
for my $did (sort { $post->{$b} / $self->{db}->{'m'. $b} |
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<=> |
<=> |
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$post->{$a} / $self->{db}->{$M, $a} |
$post->{$a} / $self->{db}->{'m'. $a} |
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} keys %$post) { |
} keys %$post) { |
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$r .= pack 'w2', $did, $post->{$did}; |
$r .= pack 'w2', $did, $post->{$did}; |
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} |
} |
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grep $occ{$_}++, &{$self->{func}}(@_); |
grep $occ{$_}++, &{$self->{func}}(@_); |
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for (keys %occ) {# may reorder posting list |
for (keys %occ) {# may reorder posting list |
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my %post = unpack 'w*', $db->{$_}; |
my %post = unpack 'w*', $db->{'p'.$_}; |
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delete $post{$key}; |
delete $post{$key}; |
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$db->{$_} = $self->sort_postings(\%post); |
$db->{'p'.$_} = $self->sort_postings(\%post); |
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_complain('delete of term', $_) if $db->{$O,$_}-1 != keys %post; |
_complain('delete of term', $_) if $db->{'o'.$_}-1 != keys %post; |
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$db->{$O,$_} = scalar keys %post; |
$db->{'o'.$_} = scalar keys %post; |
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} |
} |
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delete $db->{$M, $key}; |
delete $db->{'m'. $key}; |
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} |
} |
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sub intervall { |
sub intervall { |
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($first) = &{$self->{'ifunc'}}($first) if $first; |
($first) = &{$self->{'ifunc'}}($first) if $first; |
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($last) = &{$self->{'ifunc'}}($last) if $last; |
($last) = &{$self->{'ifunc'}}($last) if $last; |
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} |
} |
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if (defined $first and $first ne '') { # set the cursor to $first |
$first = 'p'.($first||''); |
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$dbh->seq($first, $value, R_CURSOR); |
$last = (defined $last)?'p'.$last:'q'; |
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} else { |
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$dbh->seq($first, $value, R_FIRST); |
# set the cursor to $first |
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} |
$dbh->seq($first, $value, R_CURSOR); |
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# We assume that word do not start with the character \377 |
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# $last = pack 'C', 0xff unless defined $last and $last ne ''; |
# $first would be after the last word |
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return () if defined $last and $first gt $last; # $first would be after the last word |
return () if $first gt $last; |
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push @result, $first; |
push @result, substr($first,1); |
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while (!$dbh->seq($word, $value, R_NEXT)) { |
while (!$dbh->seq($word, $value, R_NEXT)) { |
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# We should limit this to a "resonable" number of words |
# We should limit this to a "resonable" number of words |
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last if (defined $last and $word gt $last) or $word =~ /^($M|$O)/o; |
last if $word gt $last; |
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push @result, $word; |
push @result, substr($word,1); |
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} |
} |
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\@result; # speed |
\@result; # speed |
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} |
} |
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($prefix) = &{$self->{'pfunc'}}($prefix); |
($prefix) = &{$self->{'pfunc'}}($prefix); |
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} |
} |
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if ($dbh->seq($word = $prefix, $value, R_CURSOR)) { |
if ($dbh->seq($word = 'p'.$prefix, $value, R_CURSOR)) { |
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return (); |
return (); |
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} |
} |
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return () if $word !~ /^$prefix/; |
return () if $word !~ /^p$prefix/; |
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push @result, $word; |
push @result, substr($word,1); |
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while (!$dbh->seq($word, $value, R_NEXT)) { |
while (!$dbh->seq($word, $value, R_NEXT)) { |
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# We should limit this to a "resonable" number of words |
# We should limit this to a "resonable" number of words |
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last if $word !~ /^$prefix/; |
last if $word !~ /^p$prefix/; |
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push @result, $word; |
push @result, substr($word,1); |
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} |
} |
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\@result; # speed |
\@result; # speed |
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} |
} |
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# We keep duplicates |
# We keep duplicates |
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my @terms = |
my @terms = |
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# Sort words by decreasing document frequency |
# Sort words by decreasing document frequency |
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sort { $self->{db}->{$O,$a} <=> $self->{db}->{$O,$b} } |
sort { $self->{db}->{'o'.$a} <=> $self->{db}->{'o'.$b} } |
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# check which words occur in the index. |
# check which words occur in the index. |
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grep { $self->{db}->{$O,$_} } @_; |
grep { $self->{db}->{'o'.$_} } @_; |
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return () unless @terms; # nothing to search for |
return () unless @terms; # nothing to search for |
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# choping off the rest of the list will return the same ranking. |
# choping off the rest of the list will return the same ranking. |
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if ($wanted and @terms == 1) { |
if ($wanted and @terms == 1) { |
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my $term = shift @terms; |
my $term = shift @terms; |
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my $idf = log($self->{records}/$self->{db}->{$O,$term}); |
my $idf = log($self->{records}/$self->{db}->{'o'.$term}); |
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my @res; |
my @res; |
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if ($self->{reorg}) { # or not $query->{picky} |
if ($self->{reorg}) { # or not $query->{picky} |
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@res = unpack "w". int(2*$wanted), $self->{db}->{$term}; |
@res = unpack "w". int(2*$wanted), $self->{db}->{'p'.$term}; |
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} else { |
} else { |
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@res = unpack 'w*', $self->{db}->{$term}; |
@res = unpack 'w*', $self->{db}->{'p'.$term}; |
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} |
} |
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for (my $i=1; $i<@res; $i+=2) { |
for (my $i=1; $i<@res; $i+=2) { |
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$res[$i] /= $self->{db}->{$M, $res[$i-1]} / $idf; |
$res[$i] /= $self->{db}->{'m'. $res[$i-1]} / $idf; |
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} |
} |
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return @res |
return @res |
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# result. |
# result. |
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unless ($wanted) { |
unless ($wanted) { |
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for (@terms) { |
for (@terms) { |
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my $df = $self->{db}->{$O,$_}; |
my $df = $self->{db}->{'o'.$_}; |
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# The frequency *must* be 1 at least since the posting list is nonempty |
# The frequency *must* be 1 at least since the posting list is nonempty |
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_complain('search for term', $_) and $df = 1 if $df < 1; |
_complain('search for term', $_) and $df = 1 if $df < 1; |
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# Unpack posting list for current query term $_ |
# Unpack posting list for current query term $_ |
487 |
my %post = unpack 'w*', $self->{db}->{$_}; |
my %post = unpack 'w*', $self->{db}->{'p'.$_}; |
488 |
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489 |
_complain('search for term', $_) if $self->{db}->{$O,$_} != keys %post; |
_complain('search for term', $_) if $self->{db}->{'o'.$_} != keys %post; |
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# This is the inverse document frequency. The log of the inverse |
# This is the inverse document frequency. The log of the inverse |
491 |
# fraction of documents the term occurs in. |
# fraction of documents the term occurs in. |
492 |
my $idf = log($self->{records}/$df); |
my $idf = log($self->{records}/$df); |
493 |
for my $did (keys %post) { |
for my $did (keys %post) { |
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if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
495 |
$score{$did} += $post{$did} / $freq * $idf; |
$score{$did} += $post{$did} / $freq * $idf; |
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} |
} |
497 |
} |
} |
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unless ($strict) { |
unless ($strict) { |
505 |
for (@terms) { |
for (@terms) { |
506 |
# Unpack posting list for current query term $_ |
# Unpack posting list for current query term $_ |
507 |
my %post = unpack 'w*', $self->{db}->{$_}; |
my %post = unpack 'w*', $self->{db}->{'p'.$_}; |
508 |
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509 |
# Lookup the number of documents the term occurs in (document frequency) |
# Lookup the number of documents the term occurs in (document frequency) |
510 |
my $occ = $self->{db}->{$O,$_}; |
my $occ = $self->{db}->{'o'.$_}; |
511 |
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512 |
_complain('search for term', $_) if $self->{db}->{$O,$_} != keys %post; |
_complain('search for term', $_) if $self->{db}->{'o'.$_} != keys %post; |
513 |
# The frequency *must* be 1 at least since the posting list is nonempty |
# The frequency *must* be 1 at least since the posting list is nonempty |
514 |
_complain('search for term', $_) and $occ = 1 if $occ < 1; |
_complain('search for term', $_) and $occ = 1 if $occ < 1; |
515 |
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532 |
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533 |
if (keys %score < $wanted) { |
if (keys %score < $wanted) { |
534 |
for my $did (keys %post) { |
for my $did (keys %post) { |
535 |
if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
536 |
$score{$did} += $post{$did} / $freq * $idf; |
$score{$did} += $post{$did} / $freq * $idf; |
537 |
} |
} |
538 |
} |
} |
539 |
} else { |
} else { |
540 |
for my $did (keys %score) { |
for my $did (keys %score) { |
541 |
next unless exists $post{$did}; |
next unless exists $post{$did}; |
542 |
if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
543 |
$score{$did} += $post{$did} / $freq * $idf; |
$score{$did} += $post{$did} / $freq * $idf; |
544 |
} |
} |
545 |
} |
} |
559 |
for (my $i = $#terms; $i >=0; $i--) { |
for (my $i = $#terms; $i >=0; $i--) { |
560 |
local $_ = $terms[$i]; |
local $_ = $terms[$i]; |
561 |
# Lookup the number of documents the term occurs in (document frequency) |
# Lookup the number of documents the term occurs in (document frequency) |
562 |
my $df = $self->{db}->{$O,$_}; |
my $df = $self->{db}->{'o'.$_}; |
563 |
|
|
564 |
# The frequency *must* be 1 at least since the posting list is nonempty |
# The frequency *must* be 1 at least since the posting list is nonempty |
565 |
_complain('search for term', $_) and $df = 1 if $df < 1; |
_complain('search for term', $_) and $df = 1 if $df < 1; |
570 |
|
|
571 |
my ($did,$occ); |
my ($did,$occ); |
572 |
if ($self->{reorg}) { |
if ($self->{reorg}) { |
573 |
($did,$occ) = unpack 'w2', $self->{db}->{$_}; |
($did,$occ) = unpack 'w2', $self->{db}->{'p'.$_}; |
574 |
} else { # Maybe this costs more than it helps |
} else { # Maybe this costs more than it helps |
575 |
($did,$occ) = unpack 'w2', $self->sort_postings($self->{db}->{$_}); |
($did,$occ) = unpack 'w2', $self->sort_postings($self->{db}->{'p'.$_}); |
576 |
} |
} |
577 |
my $freq = $self->{db}->{$M, $did}; |
my $freq = $self->{db}->{'m'. $did}; |
578 |
my $max = $occ/$freq*$idf[$i]; |
my $max = $occ/$freq*$idf[$i]; |
579 |
$max[$i] = $max + $max[$i+1]; |
$max[$i] = $max + $max[$i+1]; |
580 |
} |
} |
584 |
my $term = $terms[$i]; |
my $term = $terms[$i]; |
585 |
# Unpack posting list for current query term $term. We loose the |
# Unpack posting list for current query term $term. We loose the |
586 |
# sorting order because the assignment to a hash. |
# sorting order because the assignment to a hash. |
587 |
my %post = unpack 'w*', $self->{db}->{$term}; |
my %post = unpack 'w*', $self->{db}->{'p'.$term}; |
588 |
|
|
589 |
_complain('search for term', $term) |
_complain('search for term', $term) |
590 |
if $self->{db}->{$O,$term} != keys %post; |
if $self->{db}->{'o'.$term} != keys %post; |
591 |
|
|
592 |
my $idf = $idf[$i]; |
my $idf = $idf[$i]; |
593 |
my $full; # Need to process all postings |
my $full; # Need to process all postings |
616 |
if (defined $chop) { |
if (defined $chop) { |
617 |
# We might be able to avoid allocating accumulators |
# We might be able to avoid allocating accumulators |
618 |
for my $did (keys %post) { |
for my $did (keys %post) { |
619 |
if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
620 |
my $wgt = $post{$did} / $freq * $idf; |
my $wgt = $post{$did} / $freq * $idf; |
621 |
# We add an accumulator if $wgt exeeds $chop |
# We add an accumulator if $wgt exeeds $chop |
622 |
if (exists $score{$did} or $wgt > $chop) { |
if (exists $score{$did} or $wgt > $chop) { |
627 |
} else { |
} else { |
628 |
# Allocate acumulators for each seen document. |
# Allocate acumulators for each seen document. |
629 |
for my $did (keys %post) { |
for my $did (keys %post) { |
630 |
if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
631 |
$score{$did} += $post{$did} / $freq * $idf; |
$score{$did} += $post{$did} / $freq * $idf; |
632 |
} |
} |
633 |
} |
} |
636 |
# Update existing accumulators |
# Update existing accumulators |
637 |
for my $did (keys %score) { |
for my $did (keys %score) { |
638 |
next unless exists $post{$did}; |
next unless exists $post{$did}; |
639 |
if (my $freq = $self->{db}->{$M, $did}) { |
if (my $freq = $self->{db}->{'m'. $did}) { |
640 |
$score{$did} += $post{$did} / $freq * $idf; |
$score{$did} += $post{$did} / $freq * $idf; |
641 |
} |
} |
642 |
} |
} |
659 |
|
|
660 |
$self->sync; |
$self->sync; |
661 |
while (my($key, $value) = each %{$self->{db}}) { |
while (my($key, $value) = each %{$self->{db}}) { |
662 |
next if $key =~ /^\377[om]/; |
next if $key !~ /^p/; |
663 |
$self->{db}->{$key} = $self->sort_postings($value); |
$self->{db}->{$key} = $self->sort_postings($value); |
664 |
} |
} |
665 |
$self->{reorg} = 1; |
$self->{reorg} = 1; |
672 |
print STDERR "Flushing $self->{cached} postings\n" if $self->{cached}; |
print STDERR "Flushing $self->{cached} postings\n" if $self->{cached}; |
673 |
while (my($key, $value) = each %{$self->{cache}}) { |
while (my($key, $value) = each %{$self->{cache}}) { |
674 |
if ($self->{reorg}) { |
if ($self->{reorg}) { |
675 |
$self->{db}->{$key} = $self->sort_postings($self->{db}->{$key} |
$self->{db}->{'p'.$key} = $self->sort_postings($self->{db}->{'p'.$key} |
676 |
. $value); |
. $value); |
677 |
} else { |
} else { |
678 |
$self->{db}->{$key} .= $value; |
$self->{db}->{'p'.$key} .= $value; |
679 |
} |
} |
680 |
} |
} |
681 |
while (my($key, $value) = each %{$self->{cdict}}) { |
while (my($key, $value) = each %{$self->{cdict}}) { |
682 |
$self->{db}->{$key} = 0 unless $self->{db}->{$key}; |
$self->{db}->{'o'.$key} = 0 unless $self->{db}->{'o'.$key}; |
683 |
$self->{db}->{$key} += $value; |
$self->{db}->{'o'.$key} += $value; |
684 |
} |
} |
685 |
$self->{cache} = {}; |
$self->{cache} = {}; |
686 |
$self->{cdict} = {}; |
$self->{cdict} = {}; |