Amazon CloudWatch metrics and Aurora MySQL status variables for write forwarding - Amazon Aurora
Metrics for writer DB instancesMetrics for reader DB instances

Amazon CloudWatch metrics and Aurora MySQL status variables for write forwarding

The following Amazon CloudWatch metrics and Aurora MySQL status variables apply when you use write forwarding for Aurora MySQL. For more information about metrics for Aurora MySQL writer and reader DB instances, see the following topics.

Metrics for write forwarding for Aurora MySQL writer DB instances

The following Amazon CloudWatch metrics and Aurora MySQL status variables apply when you use write forwarding on one or more DB clusters. These metrics and status variables are all measured on the writer DB instance.

CloudWatch metric Aurora MySQL status variable Unit Description

ForwardingWriterDMLLatency

 – Milliseconds

Average time to process each forwarded DML statement on the writer DB instance.

It doesn't include the time for the DB cluster to forward the write request, or the time to replicate changes back to the writer.

ForwardingWriterDMLThroughput

– Count per second Number of forwarded DML statements processed each second by this writer DB instance.

ForwardingWriterOpenSessions

 Aurora_fwd_writer_open_sessions Count Number of forwarded sessions on the writer DB instance.

–

 Aurora_fwd_writer_dml_stmt_count Count Total number of DML statements forwarded to this writer DB instance.

–

 Aurora_fwd_writer_dml_stmt_duration Microseconds Total duration of DML statements forwarded to this writer DB instance.

–

 Aurora_fwd_writer_select_stmt_count Count Total number of SELECT statements forwarded to this writer DB instance.

–

 Aurora_fwd_writer_select_stmt_duration Microseconds Total duration of SELECT statements forwarded to this writer DB instance.

Metrics for write forwarding for Aurora MySQL reader DB instances

The following CloudWatch metrics and Aurora MySQL status variables are measured on each reader DB instance in a DB cluster with write forwarding enabled.

CloudWatch metric Aurora MySQL status variable Unit Description

ForwardingReplicaDMLLatency

 – Milliseconds Average response time of forwarded DMLs on replica.

ForwardingReplicaDMLThroughput

 – Count per second Number of forwarded DML statements processed each second.

ForwardingReplicaOpenSessions

 Aurora_fwd_replica_open_sessions Count Number of sessions that are using write forwarding on a reader DB instance.

ForwardingReplicaReadWaitLatency

 – Milliseconds

Average wait time that a SELECT statement on a reader DB instance waits to catch up to the writer.

The degree to which the reader DB instance waits before processing a query depends on the aurora_replica_read_consistency setting.

ForwardingReplicaReadWaitThroughput

 – Count per second Total number of SELECT statements processed each second in all sessions that are forwarding writes.

ForwardingReplicaSelectLatency

 – Milliseconds Forwarded SELECT latency, averaged over all forwarded SELECT statements within the monitoring period.

ForwardingReplicaSelectThroughput

 – Count per second Forwarded SELECT throughput per second average within the monitoring period.

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 Aurora_fwd_replica_dml_stmt_count Count Total number of DML statements forwarded from this reader DB instance.

–

 Aurora_fwd_replica_dml_stmt_duration Microseconds Total duration of all DML statements forwarded from this reader DB instance.

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 Aurora_fwd_replica_errors_session_limit Count

Number of sessions rejected by the primary cluster due to one of the following error conditions:

  • writer full

  • Too many forwarded statements in progress.

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 Aurora_fwd_replica_read_wait_count Count Total number of read-after-write waits on this reader DB instance.

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 Aurora_fwd_replica_read_wait_duration Microseconds Total duration of waits due to the read consistency setting on this reader DB instance.

–

 Aurora_fwd_replica_select_stmt_count Count Total number of SELECT statements forwarded from this reader DB instance.

–

 Aurora_fwd_replica_select_stmt_duration Microseconds Total duration of SELECT statements forwarded from this reader DB instance.