Merge pull request #4332 from Icinga/feature/support-for-null-comparisons

Transform `*` equal/unequal comparisons to NULL checks

library/Icinga/Data/Db/DbConnection.php

@@ -554,19 +554,13 @@ class DbConnection implements Selectable, Extensible, Updatable, Reducible, Insp
             );
         } elseif ($sign === '=' && strpos($value, '*') !== false) {
             if ($value === '*') {
-                // We'll ignore such filters as it prevents index usage and because "*" means anything, so whether we're
+                return $column . ' IS NOT NULL';
-                // using a real column with a valid comparison here or just an expression which can only be evaluated to
-                // true makes no difference, except for performance reasons...
-                return new Zend_Db_Expr('TRUE');
             }
 
             return $column . ' LIKE ' . $this->dbAdapter->quote(preg_replace('~\*~', '%', $value));
         } elseif ($sign === '!=' && strpos($value, '*') !== false) {
             if ($value === '*') {
-                // We'll ignore such filters as it prevents index usage and because "*" means nothing, so whether we're
+                return $column . ' IS NULL';
-                // using a real column with a valid comparison here or just an expression which cannot be evaluated to
-                // true makes no difference, except for performance reasons...
-                return new Zend_Db_Expr('FALSE');
             }
 
             return sprintf(

library/Icinga/Data/Db/DbQuery.php

@@ -327,13 +327,13 @@ class DbQuery extends SimpleQuery
             return '(' . implode(" $operator ", $sql) . ')';
         } elseif ($sign === '=' && strpos($expression, '*') !== false) {
             if ($expression === '*') {
-                return new Zend_Db_Expr('TRUE');
+                return $col . ' IS NOT NULL';
             }
 
             return $col . ' LIKE ' . $this->escapeForSql($this->escapeWildcards($expression));
         } elseif ($sign === '!=' && strpos($expression, '*') !== false) {
             if ($expression === '*') {
-                return new Zend_Db_Expr('FALSE');
+                return $col . ' IS NULL';
             }
 
             return sprintf(

modules/monitoring/library/Monitoring/Backend/Ido/Query/IdoQuery.php

@@ -665,10 +665,6 @@ abstract class IdoQuery extends DbQuery
     protected function requireFilterColumns(Filter $filter)
     {
         if ($filter instanceof FilterExpression) {
-            if ($filter->getExpression() === '*') {
-                return; // Wildcard only filters are ignored so stop early here to avoid joining a table for nothing
-            }
-
             $alias = $filter->getColumn();
 
             $virtualTable = $this->aliasToTableName($alias);
@@ -774,10 +770,6 @@ abstract class IdoQuery extends DbQuery
 
     public function where($condition, $value = null)
     {
-        if ($value === '*') {
-            return $this; // Wildcard only filters are ignored so stop early here to avoid joining a table for nothing
-        }
-
         $this->requireColumn($condition);
         $col = $this->getMappedField($condition);
         if ($col === null) {