Bug 19502: Retrieve index.max_result_window from ES

This avoid hardcoding '10000' in two different places and allow users to
adjust this setting.

Also, this patch fixes a bug when the search return less than 10000
results

Test plan:
1. Do a search that returns 10000+ records.
2. Note the warning above the pagination buttons
3. Go to the last page, no error
4. Change the ES setting:
   curl -XPUT http://elasticsearch/koha_master_biblios/_settings -d \
     '{"index": {"max_result_window": 20000}}'
5. Do another search that returns more than 10000 but less than 20000
6. Note that the warning does not show up
7. Go to the last page, still no error

Signed-off-by: Nick Clemens <[email protected]>
Signed-off-by: Alex Arnaud <[email protected]>

Signed-off-by: Nick Clemens <[email protected]>

Koha/SearchEngine/Elasticsearch/Search.pm

@@ -399,6 +399,25 @@ sub json2marc {
     return $marc;
 }
 
+sub max_result_window {
+    my ($self) = @_;
+
+    $self->store(
+        Catmandu::Store::ElasticSearch->new(%{ $self->get_elasticsearch_params })
+    ) unless $self->store;
+
+    my $index_name = $self->store->index_name;
+    my $settings = $self->store->es->indices->get_settings(
+        index  => $index_name,
+        params => { include_defaults => 1, flat_settings => 1 },
+    );
+
+    my $max_result_window = $settings->{$index_name}->{settings}->{'index.max_result_window'};
+    $max_result_window //= $settings->{$index_name}->{defaults}->{'index.max_result_window'};
+
+    return $max_result_window;
+}
+
 =head2 _convert_facets
 
     my $koha_facets = _convert_facets($es_facets, $expanded_facet);

Koha/SearchEngine/Zebra/Search.pm

@@ -110,4 +110,6 @@ sub search_auth_compat {
     C4::AuthoritiesMarc::SearchAuthorities(@params);
 }
 
+sub max_result_window { undef }
+
 1;

catalogue/search.pl

@@ -619,7 +619,8 @@ =head3 Additional Notes
             ## FIXME: add a global function for this, it's better than the current global one
             ## Build the page numbers on the bottom of the page
             my @page_numbers;
-            my $hits_to_paginate = C4::Context->preference('SearchEngine') eq 'Elasticsearch' ? 10000 : $hits;
+            my $max_result_window = $searcher->max_result_window;
+            my $hits_to_paginate = ($max_result_window && $max_result_window < $hits) ? $max_result_window : $hits;
             $template->param( hits_to_paginate => $hits_to_paginate );
             # total number of pages there will be
             my $pages = ceil($hits_to_paginate / $results_per_page);

opac/opac-search.pl

@@ -830,7 +830,8 @@ sub _input_cgi_parse {
 	    }
             ## Build the page numbers on the bottom of the page
             my @page_numbers;
-            my $hits_to_paginate = C4::Context->preference('SearchEngine') eq 'Elasticsearch' ? 10000 : $hits;
+            my $max_result_window = $searcher->max_result_window;
+            my $hits_to_paginate = ($max_result_window && $max_result_window < $hits) ? $max_result_window : $hits;
             $template->param( hits_to_paginate => $hits_to_paginate );
             # total number of pages there will be
             my $pages = ceil($hits_to_paginate / $results_per_page);

t/db_dependent/Koha_SearchEngine_Elasticsearch_Search.t

@@ -17,10 +17,12 @@
 
 use Modern::Perl;
 
-use Test::More tests => 13;
+use Test::More tests => 15;
 use t::lib::Mocks;
 
 use Koha::SearchEngine::Elasticsearch::QueryBuilder;
+use Koha::SearchEngine::Elasticsearch::Indexer;
+
 
 my $builder = Koha::SearchEngine::Elasticsearch::QueryBuilder->new( { index => 'mydb' } );
 
@@ -41,9 +43,11 @@ SKIP: {
 
     eval { $builder->get_elasticsearch_params; };
 
-    skip 'ElasticSeatch configuration not available', 6
+    skip 'ElasticSeatch configuration not available', 8
         if $@;
 
+    Koha::SearchEngine::Elasticsearch::Indexer->new({ index => 'mydb' })->drop_index;
+
     ok( my $results = $searcher->search( $query) , 'Do a search ' );
 
     ok( my $marc = $searcher->json2marc( $results->first ), 'Convert JSON to MARC');
@@ -56,6 +60,13 @@ SKIP: {
 
     is ( $count = $searcher->count_auth_use($searcher,1), 0, 'Testing count_auth_use');
 
+    is ($searcher->max_result_window, 10000, 'By default, max_result_window is 10000');
+    $searcher->store->es->indices->put_settings(index => $searcher->store->index_name, body => {
+        'index' => {
+            'max_result_window' => 12000,
+        },
+    });
+    is ($searcher->max_result_window, 12000, 'max_result_window returns the correct value');
 }
 
 subtest 'json2marc' => sub {