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Automatically indexed fields - Amazon CloudWatch Logs

Automatically indexed fields

CloudWatch Logs automatically indexes fields based on their recent use in CloudWatch Logs Insights equality filters that use the = or IN operators. These indexes are in addition to default field indexes and the field indexes that you configure in policies. You do not need to configure a policy for automatically indexed fields.

CloudWatch Logs updates the set of automatically indexed fields based on recent query activity. When CloudWatch Logs removes a field from the set, it stops indexing newly ingested events for that field. CloudWatch Logs manages automatically indexed fields and retains them for 30 days. To keep a field indexed permanently, add it to an account-level or log-group level field index policy.

Use filter instead of filterIndex for automatically indexed fields

We recommend that you use filter instead of filterIndex with automatically indexed fields. CloudWatch Logs can update or remove these fields based on query patterns. CloudWatch Logs retains them for only 30 days. The filterIndex command returns only indexed data. Because CloudWatch Logs updates the set based on query activity, a filterIndex query does not search events ingested before CloudWatch Logs selected the field or after CloudWatch Logs stopped indexing it. If you use filterIndex, add the field to a field index policy to keep it indexed regardless of query activity. For more information, see filterIndex compared to filter.

The Field indexes tab for a log group lists automatically indexed fields.

You can also use the DescribeFieldIndexes operation to list automatically indexed fields. Include AUTO in the indexCategories request parameter. The response sets indexCategory to AUTO for automatically indexed fields. Requests that omit indexCategories do not return automatically indexed fields.

To add an automatically indexed field to a log-group level index policy
  1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

  2. In the left navigation pane, choose Logs, Log groups.

  3. Choose the name of the log group.

  4. Choose the Field indexes tab, and then choose Manage field indexes.

  5. On the Manage log group level field indexes page, review the fields in the policy. Add or remove fields as needed, and then choose Save.