Index: tests/Zend/Db/Table/TestCommon.php
===================================================================
--- tests/Zend/Db/Table/TestCommon.php>-(revision 16264)
+++ tests/Zend/Db/Table/TestCommon.php>-(working copy)
@@ -643,6 +643,28 @@
         $this->assertEquals(5, $lastInsertId);
     }   
-
+    /**
+     * @group ZF-2953
+     */
+    public function testTableInsertWithNoLengthPrimaryKeyField()
+    {
+        $table = $this->_table['bugs'];
+        $row = array (
+            'bug_id'          => '',
+            'bug_description' => 'New bug',
+            'bug_status'      => 'NEW',
+            'created_on'      => '2007-04-02',
+            'updated_on'      => '2007-04-02',
+            'reported_by'     => 'micky',
+            'assigned_to'     => 'goofy',
+            'verified_by'     => 'dduck'
+        );
+        $insertResult = $table->insert($row);
+        $lastInsertId = $this->_db->lastInsertId();
+        $this->assertEquals($insertResult, $lastInsertId);
+        $this->assertEquals(6, $lastInsertId);
+    }
+
     public function testTableInsertWithSchema()
     {   
         $schemaName = $this->_util->getSchema();
Index: library/Zend/Db/Table/Abstract.php
===================================================================
--- library/Zend/Db/Table/Abstract.php>-(revision 16264)
+++ library/Zend/Db/Table/Abstract.php>-(working copy)
@@ -952,7 +952,7 @@
          * If the primary key can be generated automatically, and no value was 
          * specified in the user-supplied data, then omit it from the tuple.
          */
-        if (array_key_exists($pkIdentity, $data) && $data[$pkIdentity] === null) {
+        if (array_key_exists($pkIdentity, $data) && strlen($data[$pkIdentity]) === 0) {
             unset($data[$pkIdentity]);
         }
-