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Amazon DynamoDB Metrics and Dimensions

Amazon DynamoDB sends metrics to CloudWatch. For more information, see Monitoring DynamoDB Tables with Amazon CloudWatch in the Amazon DynamoDB Developer Guide.

DynamoDB Metrics

The following metrics are available from Amazon DynamoDB. Note that DynamoDB only sends metrics to CloudWatch when they have a non-zero value. For example, the UserErrors metric is incremented whenever a request generates an HTTP 400 status code. If no HTTP 400 errors were encountered during a time period, CloudWatch will not provide metrics for UserErrors during that period.

Note

Amazon CloudWatch aggregates the following DynamoDB metrics at one-minute intervals:

  • ConditionalCheckFailedRequests

  • ConsumedReadCapacityUnits

  • ConsumedWriteCapacityUnits

  • ReadThrottleEvents

  • ReturnedBytes

  • ReturnedItemCount

  • ReturnedRecordsCount

  • SuccessfulRequestLatency

  • SystemErrors

  • ThrottledRequests

  • UserErrors

  • WriteThrottleEvents

For all other DynamoDB metrics, the aggregation granularity is five minutes.

Not all statistics, such as Average or Sum, are applicable for every metric. However, all of these values are available through the Amazon DynamoDB console, or by using the CloudWatch console, AWS CLI, or AWS SDKs for all metrics. In the following table, each metric has a list of Valid Statistics that is applicable to that metric.

MetricDescription
ConditionalCheckFailedRequests

The number of failed attempts to perform conditional writes. The PutItem, UpdateItem, and DeleteItem operations let you provide a logical condition that must evaluate to true before the operation can proceed. If this condition evaluates to false, ConditionalCheckFailedRequests is incremented by one.

Note

A failed conditional write will result in an HTTP 400 error (Bad Request). These events are reflected in the ConditionalCheckFailedRequests metric, but not in the UserErrors metric.

Units: Count

Dimensions: TableName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

ConsumedReadCapacityUnits

The number of read capacity units consumed over the specified time period, so you can track how much of your provisioned throughput is used. You can retrieve the total consumed read capacity for a table and all of its global secondary indexes, or for a particular global secondary index. For more information, see Provisioned Throughput in Amazon DynamoDB.

Note

Use the Sum statistic to calculate the consumed throughput. For example, get the Sum value over a span of one minute, and divide it by the number of seconds in a minute (60) to calculate the average ConsumedReadCapacityUnits per second (recognizing that this average will not highlight any large but brief spikes in read activity that occurred during that minute). You can compare the calculated value to the provisioned throughput value you provide DynamoDB.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum – Minimum number of read capacity units consumed by any individual request to the table or index.

  • Maximum – Maximum number of read capacity units consumed by any individual request to the table or index.

  • Average – Average per-request read capacity consumed.

  • Sum – Total read capacity units consumed. This is the most useful statistic for the ConsumedReadCapacityUnits metric.

  • SampleCount – Number of requests to DynamoDB that consumed read capacity.

ConsumedWriteCapacityUnits

The number of write capacity units consumed over the specified time period, so you can track how much of your provisioned throughput is used. You can retrieve the total consumed write capacity for a table and all of its global secondary indexes, or for a particular global secondary index. For more information, see Provisioned Throughput in Amazon DynamoDB.

Note

Use the Sum statistic to calculate the consumed throughput. For example, get the Sum value over a span of one minute, and divide it by the number of seconds in a minute (60) to calculate the average ConsumedWriteCapacityUnits per second (recognizing that this average will not highlight any large but brief spikes in write activity that occurred during that minute). You can compare the calculated value to the provisioned throughput value you provide DynamoDB.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum – Minimum number of write capacity units consumed by any individual request to the table or index.

  • Maximum – Maximum number of write capacity units consumed by any individual request to the table or index.

  • Average – Average per-request write capacity consumed.

  • Sum – Total write capacity units consumed. This is the most useful statistic for the ConsumedWriteCapacityUnits metric.

  • SampleCount – Number of requests to DynamoDB that consumed write capacity.

OnlineIndexConsumedWriteCapacity

The number of write capacity units consumed when adding a new global secondary index to a table. If the write capacity of the index is too low, incoming write activity during the backfill phase might be throttled; this can increase the time it takes to create the index. You should monitor this statistic while the index is being built to determine whether the write capacity of the index is underprovisioned.

You can adjust the write capacity of the index using the UpdateTable operation, even while the index is still being built.

Note that the ConsumedWriteCapacityUnits metric for the index does not include the write throughput consumed during index creation.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

OnlineIndexPercentageProgress

The percentage of completion when a new global secondary index is being added to a table. DynamoDB must first allocate resources for the new index, and then backfill attributes from the table into the index. For large tables, this process might take a long time. You should monitor this statistic to view the relative progress as DynamoDB builds the index.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

OnlineIndexThrottleEvents

The number of write throttle events that occur when adding a new global secondary index to a table. These events indicate that the index creation will take longer to complete, because incoming write activity is exceeding the provisioned write throughput of the index.

You can adjust the write capacity of the index using the UpdateTable operation, even while the index is still being built.

Note that the WriteThrotttleEvents metric for the index does not include any throttle events that occur during index creation.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

ProvisionedReadCapacityUnits

The number of provisioned read capacity units for a table or a global secondary index.

The TableName dimension returns the ProvisionedReadCapacityUnits for the table, but not for any global secondary indexes. To view ProvisionedReadCapacityUnits for a global secondary index, you must specify both TableName and GlobalSecondaryIndex.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum – Lowest setting for provisioned read capacity. If you use UpdateTable to increase read capacity, this metric shows the lowest value of provisioned ReadCapacityUnits during this time period.

  • Maximum – Highest setting for provisioned read capacity. If you use UpdateTable to decrease read capacity, this metric shows the highest value of provisioned ReadCapacityUnits during this time period.

  • Average – Average provisioned read capacity. The ProvisionedReadCapacityUnits metric is published at five-minute intervals. Therefore, if you rapidly adjust the provisioned read capacity units, this statistic might not reflect the true average.

ProvisionedWriteCapacityUnits

The number of provisioned write capacity units for a table or a global secondary index

The TableName dimension returns the ProvisionedWriteCapacityUnits for the table, but not for any global secondary indexes. To view ProvisionedWriteCapacityUnits for a global secondary index, you must specify both TableName and GlobalSecondaryIndex.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Minimum – Lowest setting for provisioned write capacity. If you use UpdateTable to increase write capacity, this metric shows the lowest value of provisioned WriteCapacityUnits during this time period.

  • Maximum – Highest setting for provisioned write capacity. If you use UpdateTable to decrease write capacity, this metric shows the highest value of provisioned WriteCapacityUnits during this time period.

  • Average – Average provisioned write capacity. The ProvisionedWriteCapacityUnits metric is published at five-minute intervals. Therefore, if you rapidly adjust the provisioned write capacity units, this statistic might not reflect the true average.

ReadThrottleEvents

Requests to DynamoDB that exceed the provisioned read capacity units for a table or a global secondary index.

A single request can result in multiple events. For example, a BatchGetItem that reads 10 items is processed as ten GetItem events. For each event, ReadThrottleEvents is incremented by one if that event is throttled. The ThrottledRequests metric for the entire BatchGetItem is not incremented unless all ten of the GetItem events are throttled.

The TableName dimension returns the ReadThrottleEvents for the table, but not for any global secondary indexes. To view ReadThrottleEvents for a global secondary index, you must specify both TableName and GlobalSecondaryIndex.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • SampleCount

  • Sum

ReturnedBytes

The number of bytes returned by GetRecords operations (Amazon DynamoDB Streams) during the specified time period.

Units: Bytes

Dimensions: Operation, StreamLabel, TableName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

ReturnedItemCount

The number of items returned by Query or Scan operations during the specified time period.

Note that the number of items returned is not necessarily the same as the number of items that were evaluated. For example, suppose you requested a Scan on a table that had 100 items, but specified a FilterExpression that narrowed the results so that only 15 items were returned. In this case, the response from Scan would contain a ScanCount of 100 and a Count of 15 returned items.

Units: Count

Dimensions: TableName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

ReturnedRecordsCount

The number of stream records returned by GetRecords operations (Amazon DynamoDB Streams) during the specified time period.

Units: Count

Dimensions: Operation, StreamLabel, TableName

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

  • Sum

SuccessfulRequestLatency

Successful requests to DynamoDB or Amazon DynamoDB Streams during the specified time period. SuccessfulRequestLatency can provide two different kinds of information:

  • The elapsed time for successful requests (Minimum, Maximum, Sum, or Average).

  • The number of successful requests (SampleCount).

SuccessfulRequestLatency reflects activity only within DynamoDB or Amazon DynamoDB Streams, and does not take into account network latency or client-side activity.

Units: Milliseconds

Dimensions: TableName, Operation

Valid Statistics:

  • Minimum

  • Maximum

  • Average

  • SampleCount

SystemErrors

Requests to DynamoDB or Amazon DynamoDB Streams that generate an HTTP 500 status code during the specified time period. An HTTP 500 usually indicates an internal service error.

Units: Count

Dimensions: All dimensions

Valid Statistics:

  • Sum

  • SampleCount

ThrottledRequests

Requests to DynamoDB that exceed the provisioned throughput limits on a resource (such as a table or an index).

ThrottledRequests is incremented by one if any event within a request exceeds a provisioned throughput limit. For example, if you update an item in a table with global secondary indexes, there are multiple events—a write to the table, and a write to each index. If one or more of these events are throttled, then ThrottledRequests is incremented by one.

Note

In a batch request (BatchGetItem or BatchWriteItem), ThrottledRequests is only incremented if every request in the batch is throttled.

If any individual request within the batch is throttled, one of the following metrics is incremented:

  • ReadThrottleEvents – For a throttled GetItem event within BatchGetItem.

  • WriteThrottleEvents – For a throttled PutItem or DeleteItem event within BatchWriteItem.

To gain insight into which event is throttling a request, compare ThrottledRequests with the ReadThrottleEvents and WriteThrottleEvents for the table and its indexes.

Note

A throttled request will result in an HTTP 400 status code. All such events are reflected in the ThrottledRequests metric, but not in the UserErrors metric.

Units: Count

Dimensions: TableName, Operation

Valid Statistics:

  • Sum

  • SampleCount

UserErrors

Requests to DynamoDB or Amazon DynamoDB Streams that generate an HTTP 400 status code during the specified time period. An HTTP 400 usually indicates a client-side error such as an invalid combination of parameters, attempting to update a nonexistent table, or an incorrect request signature.

All such events are reflected in the UserErrors metric, except for the following:

  • ProvisionedThroughputExceededException – See the ThrottledRequests metric in this section.

  • ConditionalCheckFailedException – See the ConditionalCheckFailedRequests metric in this section.

UserErrors represents the aggregate of HTTP 400 errors for DynamoDB or Amazon DynamoDB Streams requests for the current region and the current AWS account.

Units: Count

Dimensions: All dimensions

Valid Statistics:

  • Sum

  • SampleCount

WriteThrottleEvents

Requests to DynamoDB that exceed the provisioned write capacity units for a table or a global secondary index.

A single request can result in multiple events. For example, a PutItem request on a table with three global secondary indexes would result in four events—the table write, and each of the three index writes. For each event, the WriteThrottleEvents metric is incremented by one if that event is throttled. For single PutItem requests, if any of the events are throttled, ThrottledRequests is also incremented by one. For BatchWriteItem, the ThrottledRequests metric for the entire BatchWriteItem is not incremented unless all of the individual PutItem or DeleteItem events are throttled.

The TableName dimension returns the WriteThrottleEvents for the table, but not for any global secondary indexes. To view WriteThrottleEvents for a global secondary index, you must specify both TableName and GlobalSecondaryIndex.

Units: Count

Dimensions: TableName, GlobalSecondaryIndexName

Valid Statistics:

  • Sum

  • SampleCount

Dimensions for DynamoDB Metrics

The metrics for DynamoDB are qualified by the values for the account, table name, global secondary index name, or operation. You can use the CloudWatch console to retrieve DynamoDB data along any of the dimensions in the table below.

Dimension

Description

GlobalSecondaryIndexName

This dimension limits the data to a global secondary index on a table. If you specify GlobalSecondaryIndexName, you must also specify TableName.

Operation

This dimension limits the data to one of the following DynamoDB operations:

  • PutItem

  • DeleteItem

  • UpdateItem

  • GetItem

  • BatchGetItem

  • Scan

  • Query

  • BatchWriteItem

In addition, you can limit the data to the following Amazon DynamoDB Streams operation:

  • GetRecords

StreamLabel

This dimension limits the data to a specific stream label. It is used with metrics originating from Amazon DynamoDB Streams GetRecords operations.

TableName

This dimension limits the data to a specific table. This value can be any table name in the current region and the current AWS account.