#76819 by smsimms and sammys. Move part of the sql rewriting down into the...

#76819 by smsimms and sammys. Move part of the sql rewriting down into the database abstraction layer and add extra rewriting needed only for Postgres.

includes/database.inc

@@ -261,9 +261,7 @@ function db_rewrite_sql($query, $primary_table = 'n', $primary_field = 'nid',  $
   list($join, $where, $distinct) = _db_rewrite_sql($query, $primary_table, $primary_field, $args);
 
   if ($distinct) {
-    $field_to_select = 'DISTINCT('. $primary_table .'.'. $primary_field .')';
-    // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
-    $query = preg_replace('/(SELECT.*)('. $primary_table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $primary_table .'\.)'. $primary_field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query);
+    $query = db_distinct_field($primary_table, $primary_field, $query);
   }
 
   if (!empty($where) || !empty($join)) {

includes/database.mysql.inc

@@ -417,6 +417,23 @@ function db_table_exists($table) {
   return db_num_rows(db_query("SHOW TABLES LIKE '{" . db_escape_table($table) . "}'"));
 }
 
+/**
+ * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to
+ * the SELECT list entry of the given query and the resulting query is returned.
+ * This function only applies the wrapper if a DISTINCT doesn't already exist in
+ * the query.
+ *
+ * @param $table Table containing the field to set as DISTINCT
+ * @param $field Field to set as DISTINCT
+ * @param $query Query to apply the wrapper to
+ * @return SQL query with the DISTINCT wrapper surrounding the given table.field.
+ */
+function db_distinct_field($table, $field, $query) {
+  $field_to_select = 'DISTINCT('. $table .'.'. $field .')';
+  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
+  return preg_replace('/(SELECT.*)('. $table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query);
+}
+
 /**
  * @} End of "ingroup database".
  */

includes/database.mysqli.inc

@@ -412,6 +412,23 @@ function db_table_exists($table) {
   return db_num_rows(db_query("SHOW TABLES LIKE '{" . db_escape_table($table) . "}'"));
 }
 
+/**
+ * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to
+ * the SELECT list entry of the given query and the resulting query is returned.
+ * This function only applies the wrapper if a DISTINCT doesn't already exist in
+ * the query.
+ *
+ * @param $table Table containing the field to set as DISTINCT
+ * @param $field Field to set as DISTINCT
+ * @param $query Query to apply the wrapper to
+ * @return SQL query with the DISTINCT wrapper surrounding the given table.field.
+ */
+function db_distinct_field($table, $field, $query) {
+  $field_to_select = 'DISTINCT('. $table .'.'. $field .')';
+  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
+  return preg_replace('/(SELECT.*)('. $table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query);
+}
+
 /**
  * @} End of "ingroup database".
  */

includes/database.pgsql.inc

@@ -400,6 +400,25 @@ function db_check_setup() {
   }
 }
 
+/**
+ * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to
+ * the SELECT list entry of the given query and the resulting query is returned.
+ * This function only applies the wrapper if a DISTINCT doesn't already exist in
+ * the query.
+ *
+ * @param $table Table containing the field to set as DISTINCT
+ * @param $field Field to set as DISTINCT
+ * @param $query Query to apply the wrapper to
+ * @return SQL query with the DISTINCT wrapper surrounding the given table.field.
+ */
+function db_distinct_field($table, $field, $query) {
+  $field_to_select = 'DISTINCT ON ('. $table .'.'. $field .") $table.$field";
+  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
+  $query = preg_replace('/(SELECT.*)('. $table .'\.)?(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1'. $field_to_select .'\3', $query);
+  $query = preg_replace('/(ORDER BY )(?!'.$table.'\.'.$field.')/', '\1'."$table.$field, ", $query);
+  return $query;
+}
+
 /**
  * @} End of "ingroup database".
  */