# Enabling MariaDB binary log annotation
<a name="USER_LogAccess.MariaDB.BinarylogAnnotation"></a>

In a MariaDB DB instance, you can use the `Annotate_rows` event to annotate a row event with a copy of the SQL query that caused the row event. This approach provides similar functionality to enabling the `binlog_rows_query_log_events` parameter on an RDS for MySQL DB instance.

You can enable binary log annotations globally by creating a custom parameter group and setting the `binlog_annotate_row_events` parameter to **1**. You can also enable annotations at the session level, by calling `SET SESSION binlog_annotate_row_events = 1`. Use the `replicate_annotate_row_events` to replicate binary log annotations to the replica instance if binary logging is enabled on it. No special privileges are required to use these settings.

The following is an example of a row-based transaction in MariaDB. The use of row-based logging is triggered by setting the transaction isolation level to read-committed.

```
CREATE DATABASE IF NOT EXISTS test;
USE test;
CREATE TABLE square(x INT PRIMARY KEY, y INT NOT NULL) ENGINE = InnoDB;
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN
INSERT INTO square(x, y) VALUES(5, 5 * 5);
COMMIT;
```

Without annotations, the binary log entries for the transaction look like the following:

```
BEGIN
/*!*/;
# at 1163
# at 1209
#150922  7:55:57 server id 1855786460  end_log_pos 1209         Table_map: `test`.`square` mapped to number 76
#150922  7:55:57 server id 1855786460  end_log_pos 1247         Write_rows: table id 76 flags: STMT_END_F
### INSERT INTO `test`.`square`
### SET
###   @1=5
###   @2=25
# at 1247
#150922  7:56:01 server id 1855786460  end_log_pos 1274         Xid = 62
COMMIT/*!*/;
```

The following statement enables session-level annotations for this same transaction, and disables them after committing the transaction:

```
CREATE DATABASE IF NOT EXISTS test;
USE test;
CREATE TABLE square(x INT PRIMARY KEY, y INT NOT NULL) ENGINE = InnoDB;
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
SET SESSION binlog_annotate_row_events = 1;
BEGIN;
INSERT INTO square(x, y) VALUES(5, 5 * 5);
COMMIT;
SET SESSION binlog_annotate_row_events = 0;
```

With annotations, the binary log entries for the transaction look like the following:

```
BEGIN
/*!*/;
# at 423
# at 483
# at 529
#150922  8:04:24 server id 1855786460  end_log_pos 483  Annotate_rows:
#Q> INSERT INTO square(x, y) VALUES(5, 5 * 5)
#150922  8:04:24 server id 1855786460  end_log_pos 529  Table_map: `test`.`square` mapped to number 76
#150922  8:04:24 server id 1855786460  end_log_pos 567  Write_rows: table id 76 flags: STMT_END_F
### INSERT INTO `test`.`square`
### SET
###   @1=5
###   @2=25
# at 567
#150922  8:04:26 server id 1855786460  end_log_pos 594  Xid = 88
COMMIT/*!*/;
```