diff --git a/src/NestedSetSchemaInterface.php b/src/NestedSetSchemaInterface.php
new file mode 100644
index 00000000..b9d7431d
--- /dev/null
+++ b/src/NestedSetSchemaInterface.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace PNX\NestedSet;
+
+/**
+ * Provides Nested Set schema operations.
+ */
+interface NestedSetSchemaInterface {
+
+  /**
+   * Creates the nested set table.
+   */
+  public function create();
+
+  /**
+   * Drops the nested set table.
+   */
+  public function drop();
+
+}
diff --git a/src/Storage/BaseDbalStorage.php b/src/Storage/BaseDbalStorage.php
new file mode 100644
index 00000000..f1d131e3
--- /dev/null
+++ b/src/Storage/BaseDbalStorage.php
@@ -0,0 +1,65 @@
+<?php
+
+namespace PNX\NestedSet\Storage;
+
+use Doctrine\DBAL\Connection;
+
+/**
+ * Abstract base class for DBAL storage classes.
+ */
+abstract class BaseDbalStorage {
+
+  /**
+   * The regex for validating table names.
+   */
+  const VALID_TABLE_REGEX = '/^[a-zA-Z]\w{1,64}$/';
+
+  /**
+   * The database connection.
+   *
+   * @var \Doctrine\DBAL\Connection
+   */
+  protected $connection;
+
+  /**
+   * The table name to use for storing the nested set.
+   *
+   * @var string
+   */
+  protected $tableName;
+
+  /**
+   * DbalTree constructor.
+   *
+   * @param \Doctrine\DBAL\Connection $connection
+   *   The database connection.
+   * @param string $tableName
+   *   (optional) The table name to use.
+   */
+  public function __construct(Connection $connection, $tableName = 'tree') {
+    $this->connection = $connection;
+    if (!$this->validTableName($tableName)) {
+      throw new \InvalidArgumentException("Table name must match the regex " . self::VALID_TABLE_REGEX);
+    }
+    $this->tableName = $tableName;
+  }
+
+  /**
+   * Checks if the table name is valid.
+   *
+   * Table names must:
+   * - start with a letter
+   * - only contain letters, numbers, and underscores
+   * - be maximum 64 characters.
+   *
+   * @param string $tableName
+   *   The table name.
+   *
+   * @return bool
+   *   TRUE if the table name is valid.
+   */
+  protected function validTableName($tableName) {
+    return (bool) preg_match(self::VALID_TABLE_REGEX, $tableName);
+  }
+
+}
diff --git a/src/Storage/DbalNestedSet.php b/src/Storage/DbalNestedSet.php
index d19c9eeb..ef6d1785 100644
--- a/src/Storage/DbalNestedSet.php
+++ b/src/Storage/DbalNestedSet.php
@@ -2,50 +2,14 @@
 
 namespace PNX\NestedSet\Storage;
 
-use Doctrine\DBAL\Connection;
 use Exception;
-use PNX\NestedSet\Node;
 use PNX\NestedSet\NestedSetInterface;
+use PNX\NestedSet\Node;
 
 /**
  * Provides a DBAL implementation of a Tree.
  */
-class DbalNestedSet implements NestedSetInterface {
-
-  /**
-   * The regex for validating table names.
-   */
-  const VALID_TABLE_REGEX = '/^[a-zA-Z]\w{1,64}$/';
-
-  /**
-   * The database connection.
-   *
-   * @var \Doctrine\DBAL\Connection
-   */
-  protected $connection;
-
-  /**
-   * The table name to use for storing the nested set.
-   *
-   * @var string
-   */
-  protected $tableName;
-
-  /**
-   * DbalTree constructor.
-   *
-   * @param \Doctrine\DBAL\Connection $connection
-   *   The database connection.
-   * @param string $tableName
-   *   (optional) The table name to use.
-   */
-  public function __construct(Connection $connection, $tableName = 'tree') {
-    $this->connection = $connection;
-    if (!preg_match(self::VALID_TABLE_REGEX, $tableName)) {
-      throw new \InvalidArgumentException("Table name must match the regex " . self::VALID_TABLE_REGEX);
-    }
-    $this->tableName = $tableName;
-  }
+class DbalNestedSet extends BaseDbalStorage implements NestedSetInterface {
 
   /**
    * {@inheritdoc}
@@ -169,10 +133,10 @@ public function findDescendants(Node $node, $depth = 0) {
     $query->select('child.id', 'child.revision_id', 'child.left_pos', 'child.right_pos', 'child.depth')
       ->from($this->tableName, 'child')
       ->from($this->tableName, 'parent')
-      ->where('child.left_pos > parent.left_pos')
-      ->andWhere('child.right_pos < parent.right_pos')
       ->andWhere('parent.id = :id')
       ->andWhere('parent.revision_id = :revision_id')
+      ->andwhere('child.left_pos > parent.left_pos')
+      ->andWhere('child.right_pos < parent.right_pos')
       ->setParameter(':id', $node->getId())
       ->setParameter(':revision_id', $node->getRevisionId());
     if ($depth > 0) {
diff --git a/src/Storage/DbalNestedSetSchema.php b/src/Storage/DbalNestedSetSchema.php
new file mode 100644
index 00000000..d8e57b66
--- /dev/null
+++ b/src/Storage/DbalNestedSetSchema.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace PNX\NestedSet\Storage;
+
+use Doctrine\DBAL\Schema\Schema;
+use PNX\NestedSet\NestedSetSchemaInterface;
+
+/**
+ * Provides DBAL Nested set schema operations.
+ */
+class DbalNestedSetSchema extends BaseDbalStorage implements NestedSetSchemaInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function create() {
+    $schema = new Schema();
+    $tree = $schema->createTable($this->tableName);
+    $tree->addColumn("id", "integer", ["unsigned" => TRUE]);
+    $tree->addColumn("revision_id", "integer", ["unsigned" => TRUE]);
+    $tree->addColumn("left_pos", "integer", ["unsigned" => TRUE]);
+    $tree->addColumn("right_pos", "integer", ["unsigned" => TRUE]);
+    $tree->addColumn("depth", "integer", ["unsigned" => TRUE]);
+
+    $tree->setPrimaryKey(['id', 'revision_id']);
+    $tree->addIndex(['id', 'revision_id', 'left_pos', 'right_pos', 'depth']);
+    $tree->addIndex(['left_pos', 'right_pos']);
+    $tree->addIndex(['right_pos']);
+
+    foreach ($schema->toSql($this->connection->getDatabasePlatform()) as $sql) {
+      $this->connection->exec($sql);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function drop() {
+    $schema = new Schema();
+    $schema->dropTable($this->tableName);
+    foreach ($schema->toSql($this->connection->getDatabasePlatform()) as $sql) {
+      $this->connection->exec($sql);
+    }
+  }
+
+}
diff --git a/tests/Functional/DbalNestedSetTest.php b/tests/Functional/DbalNestedSetTest.php
index 4ab8152a..65b794e1 100644
--- a/tests/Functional/DbalNestedSetTest.php
+++ b/tests/Functional/DbalNestedSetTest.php
@@ -5,9 +5,9 @@
 use Console_Table;
 use Doctrine\DBAL\Configuration;
 use Doctrine\DBAL\DriverManager;
-use Doctrine\DBAL\Schema\Schema;
 use PNX\NestedSet\Node;
 use PNX\NestedSet\Storage\DbalNestedSet;
+use PNX\NestedSet\Storage\DbalNestedSetSchema;
 
 /**
  * Tests the Dbal Tree implementation.
@@ -37,18 +37,25 @@ class DbalNestedSetTest extends \PHPUnit_Framework_TestCase {
    */
   protected $tableName = 'nested_set';
 
+  /**
+   * The nested set schema.
+   *
+   * @var \PNX\NestedSet\Storage\DbalNestedSetSchema
+   */
+  protected $schema;
+
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
-    if ($this->connection === NULL) {
-      $this->connection = DriverManager::getConnection([
-        'url' => 'sqlite:///:memory:',
-      ], new Configuration());
-      $this->createTable();
-      $this->loadTestData();
-      $this->nestedSet = new DbalNestedSet($this->connection, $this->tableName);
-    }
+    $this->connection = DriverManager::getConnection([
+      'url' => 'sqlite:///:memory:',
+    ], new Configuration());
+
+    $this->schema = new DbalNestedSetSchema($this->connection, $this->tableName);
+    $this->schema->create();
+    $this->loadTestData();
+    $this->nestedSet = new DbalNestedSet($this->connection, $this->tableName);
   }
 
   /**
@@ -423,34 +430,6 @@ public function testValidateTableInvalidFirstChars() {
     $this->nestedSet = new DbalNestedSet($this->connection, "1abc");
   }
 
-  /**
-   * Drops the table.
-   */
-  protected function dropTable() {
-    $schema = new Schema();
-    $schema->dropTable("tree");
-    foreach ($schema->toSql($this->connection->getDatabasePlatform()) as $sql) {
-      $this->connection->exec($sql);
-    }
-  }
-
-  /**
-   * Creates the table.
-   */
-  protected function createTable() {
-    $schema = new Schema();
-    $tree = $schema->createTable($this->tableName);
-    $tree->addColumn("id", "integer", ["unsigned" => TRUE]);
-    $tree->addColumn("revision_id", "integer", ["unsigned" => TRUE]);
-    $tree->addColumn("left_pos", "integer", ["unsigned" => TRUE]);
-    $tree->addColumn("right_pos", "integer", ["unsigned" => TRUE]);
-    $tree->addColumn("depth", "integer", ["unsigned" => TRUE]);
-
-    foreach ($schema->toSql($this->connection->getDatabasePlatform()) as $sql) {
-      $this->connection->exec($sql);
-    }
-  }
-
   /**
    * Loads the test data.
    */