Index: php-5.2.11/ext/pdo/pdo_stmt.c
===================================================================
--- php-5.2.17/ext/pdo/pdo_stmt.c.ORIG	Wed Jun 16 16:13:29 2010
+++ php-5.2.17/ext/pdo/pdo_stmt.c	Tue Feb  1 11:42:48 2011
@@ -2321,6 +2321,54 @@
 	return -1;
 }
 
+static void init_stmt_properties(pdo_stmt_t* stmt TSRMLS_DC)
+{
+	HashTable* ht =  &stmt->ce->default_properties;
+	HashTable* target = stmt->properties;
+
+	HashPosition pos;
+	zend_hash_internal_pointer_reset_ex(ht, &pos);
+	while(zend_hash_has_more_elements_ex(ht, &pos)
+			   	== SUCCESS) {
+		ulong index;
+		char* key = NULL;
+		uint keylen = 0;
+		int ret = zend_hash_get_current_key_ex(ht,
+											   &key,
+											   &keylen,
+											   &index, 0,
+											   &pos);
+		if ((keylen == sizeof("queryString"))
+				&& (strncmp(key, "queryString", keylen) == 0)) {
+			zval* qval;
+			/* Since the value for the key queryString in
+			 * stmt->ce->default_properties is shared by multiple threads so
+			 * we can not add the same zval in stmt->properties. we need to
+			 * create a null property object. See Bug 49937 */
+			ALLOC_INIT_ZVAL(qval);
+			zend_hash_add(stmt->properties, "queryString", 
+						  sizeof("queryString"), (void**) &qval, sizeof(zval*), NULL);
+		}
+		else {
+			void* data = NULL;
+			zend_hash_get_current_data_ex(ht,
+										  (void **) &data, &pos);
+			void *new_entry = NULL;
+			if (data) {
+				/* We expect keylen should be > 0. default_properties hash
+				 * should only contain named keys */
+				if (keylen) {
+					zend_hash_quick_update(target, key, keylen, 0, data, sizeof(void*), &new_entry);
+				} 
+				if (new_entry) {
+					zval_add_ref(new_entry);
+				}
+			}
+		}
+		zend_hash_move_forward_ex(ht, &pos);
+	}
+}
+
 static zend_object_value dbstmt_clone_obj(zval *zobject TSRMLS_DC)
 {
 	zend_object_value retval;
@@ -2334,7 +2382,7 @@
 	stmt->refcount = 1;
 	ALLOC_HASHTABLE(stmt->properties);
 	zend_hash_init(stmt->properties, 0, NULL, ZVAL_PTR_DTOR, 0);
-	zend_hash_copy(stmt->properties, &stmt->ce->default_properties, (copy_ctor_func_t) zval_add_ref, (void *) &tmp, sizeof(zval *));
+	init_stmt_properties(stmt TSRMLS_CC);
 
 	old_stmt = (pdo_stmt_t *)zend_object_store_get_object(zobject TSRMLS_CC);
 	
@@ -2463,7 +2511,7 @@
 	stmt->refcount = 1;
 	ALLOC_HASHTABLE(stmt->properties);
 	zend_hash_init(stmt->properties, 0, NULL, ZVAL_PTR_DTOR, 0);
-	zend_hash_copy(stmt->properties, &ce->default_properties, (copy_ctor_func_t) zval_add_ref, (void *) &tmp, sizeof(zval *));
+	init_stmt_properties(stmt TSRMLS_CC);
 
 	retval.handle = zend_objects_store_put(stmt, (zend_objects_store_dtor_t)zend_objects_destroy_object, (zend_objects_free_object_storage_t)pdo_dbstmt_free_storage, (zend_objects_store_clone_t)dbstmt_clone_obj TSRMLS_CC);
 	retval.handlers = &pdo_dbstmt_object_handlers;