[Koha-patches] [Signed Off] [PATCH] Bug 6078: Request to find borrowers without issues overload the server

[Chris Cormack]

From: Sophie Meynieux <sophie.meynieux at biblibre.com>

Optimization of the SQL request using NOT EXISTS instead of NOT IN

BibLibre MT5946

Signed-off-by: Chris Cormack <chris at bigballofwax.co.nz>
---
 reports/borrowers_out.pl |   18 ++++++------------
 1 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/reports/borrowers_out.pl b/reports/borrowers_out.pl
index 0a135e1..278e412 100755
--- a/reports/borrowers_out.pl
+++ b/reports/borrowers_out.pl
@@ -230,18 +230,12 @@ sub calculate {
     @$filters[0]=~ s/\*/%/g if (@$filters[0]);
     $strcalc .= " AND borrowers.categorycode like '" . @$filters[0] ."'" if ( @$filters[0] );
 
-    my $strqueryfilter = "SELECT DISTINCT borrowernumber FROM  ";
-    $strqueryfilter .= "(SELECT borrowernumber from old_issues WHERE borrowernumber IS NOT NULL ";
-    if ($filters->[1]){
-        $strqueryfilter .= "AND old_issues.timestamp> '$filters->[1]' ";
-    }
-    $strqueryfilter .= "UNION SELECT borrowernumber FROM issues WHERE 1 ";
-    if ($filters->[1]){
-        $strqueryfilter .= "AND issues.timestamp> '$filters->[1]' ";
-    }
-    $strqueryfilter .= ") active_borrowers";
-
-    $strcalc .= " AND borrowers.borrowernumber not in ($strqueryfilter)";
+    $strcalc .= " AND NOT EXISTS (SELECT * FROM issues WHERE issues.borrowernumber=borrowers.borrowernumber ";
+    $strcalc .= " AND issues.timestamp> '" . @$filters[1] . "'" if (@$filters[1]);
+    $strcalc .= ") ";
+    $strcalc .= " AND NOT EXISTS (SELECT * FROM old_issues WHERE old_issues.borrowernumber=borrowers.borrowernumber ";
+    $strcalc .= " AND old_issues.timestamp> '" . @$filters[1] . "'" if (@$filters[1]);
+    $strcalc .= ") ";
     $strcalc .= " group by borrowers.borrowernumber";
     $strcalc .= ", $colfield" if ($column);
     $strcalc .= " order by $colfield " if ($colfield);
-- 
1.7.2.2