includes/database/pgsql/query.inc  |   30 +++++++++++++++++++++++++++++-
 includes/database/pgsql/schema.inc |    1 +
 2 files changed, 30 insertions(+), 1 deletions(-)

diff --git includes/database/pgsql/query.inc includes/database/pgsql/query.inc
index 8825229..338d850 100644
--- includes/database/pgsql/query.inc
+++ includes/database/pgsql/query.inc
@@ -43,6 +43,28 @@ class InsertQuery_pgsql extends InsertQuery {
           $stmt->bindParam(':db_insert_placeholder_' . $max_placeholder++, $insert_values[$idx]);
         }
       }
+      // Check if values for a serial field has been passed.
+      if (!empty($table_information->serial_fields)) {
+        foreach ($table_information->serial_fields as $index => $serial_field) {
+          $serial_key = array_search($serial_field, $this->insertFields);
+          if ($serial_key !== FALSE) {
+            $serial_value = $insert_values[$serial_key];
+
+            // Force $last_insert_id to the specified value. This is only done
+            // if $index is 0.
+            if ($index == 0) {
+              $last_insert_id = $serial_value;
+            }
+            // Set the sequence to the bigger value of either the passed
+            // value or the max value of the column. It can happen that another
+            // thread calls nextval() which could lead to a serial number being
+            // used twice. However, trying to insert a value into a serial
+            // column should only be done in very rare cases and is not thread
+            // safe by definition.
+            $this->connection->query("SELECT setval('" . $table_information->sequences[$index] . "', GREATEST(MAX(" . $serial_field . "), :serial_value)) FROM {" . $this->table . "}", array(':serial_value' => (int)$serial_value));
+          }
+        }
+      }
     }
     if (!empty($this->fromQuery)) {
       // bindParam stores only a reference to the variable that is followed when
@@ -67,7 +89,13 @@ class InsertQuery_pgsql extends InsertQuery {
     elseif ($options['return'] == Database::RETURN_INSERT_ID) {
       $options['return'] = Database::RETURN_NULL;
     }
-    $last_insert_id = $this->connection->query($stmt, array(), $options);
+    // Only use the returned last_insert_id if it is not already set.
+    if (!empty($last_insert_id)) {
+      $this->connection->query($stmt, array(), $options);
+    }
+    else {
+      $last_insert_id = $this->connection->query($stmt, array(), $options);
+    }
 
     // Re-initialize the values array so that we can re-use this query.
     $this->insertValues = array();
diff --git includes/database/pgsql/schema.inc includes/database/pgsql/schema.inc
index cda525b..1b65f5d 100644
--- includes/database/pgsql/schema.inc
+++ includes/database/pgsql/schema.inc
@@ -66,6 +66,7 @@ class DatabaseSchema_pgsql extends DatabaseSchema {
           // return the last insert id. If there is more than 1 sequences the
           // first one (index 0 of the sequences array) will be used.
           $table_information->sequences[] = $matches[1];
+          $table_information->serial_fields[] = $column->column_name;
         }
       }
       $this->tableInformation[$key] = $table_information;