#### B.3.4.5 Rollback Failure for Nontransactional Tables

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 If you receive the following message when trying to perform a [`ROLLBACK`](commit.html), it means that one or more of the tables you used in the transaction do not support transactions:

```
Warning: Some non-transactional changed tables couldn't be rolled back
```

 These nontransactional tables are not affected by the [`ROLLBACK`](commit.html) statement.

 If you were not deliberately mixing transactional and nontransactional tables within the transaction, the most likely cause for this message is that a table you thought was transactional actually is not. This can happen if you try to create a table using a transactional storage engine that is not supported by your [**mysqld**](mysqld.html) server (or that was disabled with a startup option). If [**mysqld**](mysqld.html) does not support a storage engine, it instead creates the table as a `MyISAM` table, which is nontransactional.

 You can check the storage engine for a table by using either of these statements:

```
SHOW TABLE STATUS LIKE 'tbl_name';
SHOW CREATE TABLE tbl_name;
```

 See [Section 13.7.7.38, “SHOW TABLE STATUS Statement”](show-table-status.html), and [Section 13.7.7.10, “SHOW CREATE TABLE Statement”](show-create-table.html).

 To check which storage engines your [**mysqld**](mysqld.html) server supports, use this statement:

```
SHOW ENGINES;
```

 See [Section 13.7.7.16, “SHOW ENGINES Statement”](show-engines.html) for full details.

