[2.0] DDC-169 - Add functionality to detect that an add + drop column diff is actually just a rename column.

lib/Doctrine/DBAL/Schema/Comparator.php

@@ -144,30 +144,44 @@ class Comparator
         $changes = 0;
         $tableDifferences = new TableDiff();
 
+        $table1Columns = $table1->getColumns();
+        $table2Columns = $table2->getColumns();
+
         /* See if all the fields in table 1 exist in table 2 */
-        foreach ( $table2->getColumns() as $columnName => $column ) {
+        foreach ( $table2Columns as $columnName => $column ) {
             if ( !$table1->hasColumn($columnName) ) {
                 $tableDifferences->addedColumns[$columnName] = $column;
                 $changes++;
             }
         }
         /* See if there are any removed fields in table 2 */
-        foreach ( $table1->getColumns() as $columnName => $column ) {
+        foreach ( $table1Columns as $columnName => $column ) {
             if ( !$table2->hasColumn($columnName) ) {
-                $tableDifferences->removedColumns[$columnName] = true;
+                $tableDifferences->removedColumns[$columnName] = $column;
                 $changes++;
             }
         }
         /* See if there are any changed fieldDefinitioninitions */
-        foreach ( $table1->getColumns() as $columnName => $column ) {
+        foreach ( $table1Columns as $columnName => $column ) {
             if ( $table2->hasColumn($columnName) ) {
                 if ( $this->diffColumn( $column, $table2->getColumn($columnName) ) ) {
-                    $tableDifferences->changedColumns[$columnName] = $table2->getColumn($columnName);
+                    $tableDifferences->changedColumns[$column->getName()] = $table2->getColumn($columnName);
                     $changes++;
                 }
             }
         }
 
+        // Try to find columns that only changed their name, rename operations maybe cheaper than add/drop
+        foreach ($tableDifferences->addedColumns AS $addedColumnName => $addedColumn) {
+            foreach ($tableDifferences->removedColumns AS $removedColumnName => $removedColumn) {
+                if ($this->diffColumn($addedColumn, $removedColumn) === false) {
+                    $tableDifferences->renamedColumns[$removedColumn->getName()] = $addedColumn;
+                    unset($tableDifferences->addedColumns[$addedColumnName]);
+                    unset($tableDifferences->removedColumns[$removedColumnName]);
+                }
+            }
+        }
+
         $table1Indexes = $table1->getIndexes();
         $table2Indexes = $table2->getIndexes();
 

lib/Doctrine/DBAL/Schema/TableDiff.php

@@ -55,6 +55,13 @@ class TableDiff
      */
     public $removedColumns = array();
 
+    /**
+     * Columns that are only renamed from key to column instance name.
+     *
+     * @var array(string=>Column)
+     */
+    public $renamedColumns = array();
+
     /**
      * All added indexes
      *

tests/Doctrine/Tests/DBAL/Schema/ComparatorTest.php

@@ -133,10 +133,11 @@ class ComparatorTest extends \PHPUnit_Framework_TestCase
 
     public function testCompareMissingField()
     {
+        $missingColumn = new Column('integerfield1', Type::getType('integer'));
         $schema1 = new Schema( array(
             'bugdb' => new Table('bugdb',
                 array (
-                    'integerfield1' => new Column('integerfield1', Type::getType('integer')),
+                    'integerfield1' => $missingColumn,
                     'integerfield2' => new Column('integerfield2', Type::getType('integer')),
                 )
             ),
@@ -153,7 +154,7 @@ class ComparatorTest extends \PHPUnit_Framework_TestCase
             array (
                 'bugdb' => new TableDiff( array(), array(),
                     array (
-                        'integerfield1' => true,
+                        'integerfield1' => $missingColumn,
                     )
                 )
             )
@@ -558,6 +559,23 @@ class ComparatorTest extends \PHPUnit_Framework_TestCase
         $this->assertFalse($tableDiff);
     }
 
+    public function testDetectRenameColumn()
+    {
+        $tableA = new Table("foo");
+        $tableA->createColumn('foo', 'integer');
+
+        $tableB = new Table("foo");
+        $tableB->createColumn('bar', 'integer');
+
+        $c = new Comparator();
+        $tableDiff = $c->diffTable($tableA, $tableB);
+
+        $this->assertEquals(0, count($tableDiff->addedColumns));
+        $this->assertEquals(0, count($tableDiff->removedColumns));
+        $this->assertArrayHasKey('foo', $tableDiff->renamedColumns);
+        $this->assertEquals('bar', $tableDiff->renamedColumns['foo']->getName());
+    }
+
     /**
      * @param SchemaDiff $diff
      * @param int $newTableCount