From: Mike Rylander <mrylander@gmail.com>
Date: Wed, 15 Apr 2015 16:10:27 +0000 (-0400)
Subject: LP#1438136: Teach QP to be smart about attribute selectivity
X-Git-Url: https://old-git.evergreen-ils.org/?a=commitdiff_plain;h=e3486397bb616b230da2bb8a458767bfff07eddb;p=evergreen%2Fmasslnc.git

LP#1438136: Teach QP to be smart about attribute selectivity

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
---

diff --git a/Open-ILS/src/perlmods/lib/OpenILS/Application/Storage/Driver/Pg/QueryParser.pm b/Open-ILS/src/perlmods/lib/OpenILS/Application/Storage/Driver/Pg/QueryParser.pm
index 147b16571e..ac3174facf 100644
--- a/Open-ILS/src/perlmods/lib/OpenILS/Application/Storage/Driver/Pg/QueryParser.pm
+++ b/Open-ILS/src/perlmods/lib/OpenILS/Application/Storage/Driver/Pg/QueryParser.pm
@@ -696,6 +696,7 @@ use OpenILS::Application::AppUtils;
 my $apputils = "OpenILS::Application::AppUtils";
 
 our %_dfilter_controlled_cache = ();
+our %_dfilter_stats_cache = ();
 
 sub dynamic_filter_compile {
     my ($self, $filter, $params, $negate) = @_;
@@ -703,6 +704,13 @@ sub dynamic_filter_compile {
 
     $negate = $negate ? '!' : '';
 
+    if (!scalar keys %_dfilter_stats_cache) {
+        my $data = $e->json_query({from => ['evergreen.pg_statistics', 'record_attr_vector_list', 'vlist']});
+        %_dfilter_stats_cache = map {
+            ( $_->{element}, $_->{frequency} )
+        } grep { $_->{frequency} > 5 } @$data; # Pin floor to 5% of the table
+    }
+
     if (!exists($_dfilter_controlled_cache{$filter})) {
         my $crad = $e->retrieve_config_record_attr_definition($filter);
         my $ccvm_list = $e->search_config_coded_value_map({ctype =>$filter});
@@ -718,16 +726,15 @@ sub dynamic_filter_compile {
     my $value_field = $_dfilter_controlled_cache{$filter}{controlled} ?
         'code' : 'value';
 
-    return sprintf('%s(%s)', $negate,
+    my $attr_objects = $e->$method({ $attr_field => $filter, $value_field => $params });
+    my $common = scalar(grep { exists($_dfilter_stats_cache{$_->id}) } @$attr_objects);
+    
+    return (sprintf('%s(%s)', $negate,
         join(
             '|', 
-            map {
-                $_->id
-            } @{
-                $e->$method({ $attr_field => $filter, $value_field => $params })
-            }
+            map { $_->id } @$attr_objects
         )
-    );
+    ), $common);
 }
 
 sub toSQL {
@@ -1059,6 +1066,7 @@ sub flatten {
     my $joiner = "\n" . ${spc} x ( $self->plan_level + 5 ) . ($self->joiner eq '&' ? 'AND ' : 'OR ');
 
     my @dlist = ();
+    my $common = 0;
     # for each dynamic filter, build more of the WHERE clause
     for my $filter (@{$self->filters}) {
         my $NOT = $filter->negate ? 'NOT ' : '';
@@ -1070,7 +1078,8 @@ sub flatten {
             warn "flatten(): processing dynamic filter ". $filter->name ."\n"
                 if $self->QueryParser->debug;
 
-            my $vlist_query = $self->dynamic_filter_compile( $fname, $filter->args, $filter->negate );
+            my $vlist_query;
+            ($vlist_query, $common) = $self->dynamic_filter_compile( $fname, $filter->args, $filter->negate );
 
             # bool joiner for intra-plan nodes/filters
             push(@dlist, $self->joiner) if @dlist;
@@ -1230,10 +1239,17 @@ sub flatten {
     if (@dlist) {
 
         $where .= $joiner if $where ne '';
-        $where .= sprintf(
-            'mrv.vlist @@ \'%s\'',
-            join('', @dlist)
-        );
+        if ($common) { # Use a function wrapper to inform PG of the non-rareness of one or more filter elements
+            $where .= sprintf(
+                'evergreen.query_int_wrapper(mrv.vlist, \'%s\')',
+                join('', @dlist)
+            );
+        } else {
+            $where .= sprintf(
+                'mrv.vlist @@ \'%s\'',
+                join('', @dlist)
+            );
+        }
     }
 
     warn "flatten(): full filter where => $where\n" if $self->QueryParser->debug;
diff --git a/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.vlist_freq.sql b/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.vlist_freq.sql
new file mode 100644
index 0000000000..cff061a1da
--- /dev/null
+++ b/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.vlist_freq.sql
@@ -0,0 +1,36 @@
+BEGIN;
+
+SELECT evergreen.upgrade_deps_block_check('XXXX', :eg_version);
+
+CREATE OR REPLACE FUNCTION evergreen.pg_statistics (tab TEXT, col TEXT) RETURNS TABLE(element TEXT, frequency INT) AS $$
+BEGIN
+    RETURN QUERY
+        SELECT  e,
+                f
+          FROM  (SELECT ROW_NUMBER() OVER (),
+                        (f * 100)::INT AS f
+                  FROM  (SELECT UNNEST(most_common_elem_freqs) AS f
+                          FROM  pg_stats
+                          WHERE tablename = tab
+                                AND attname = col
+                        )x
+                ) AS f
+                JOIN (SELECT ROW_NUMBER() OVER (),
+                             e
+                       FROM (SELECT UNNEST(most_common_elems::text::text[]) AS e
+                              FROM  pg_stats 
+                              WHERE tablename = tab
+                                    AND attname = col
+                            )y
+                ) AS elems USING (row_number);
+END;
+$$ LANGUAGE PLPGSQL;
+
+CREATE FUNCTION evergreen.query_int_wrapper (INT[],TEXT) RETURNS BOOL AS $$
+BEGIN
+    RETURN $1 @@ $2::query_int;
+END;
+$$ LANGUAGE PLPGSQL STABLE;
+
+COMMIT;
+