---
title: Manage data quality
description: From the Streams page, use the Data quality menu to filter your streams by data quality status, then select a stream to examine it more closely. After...
url: https://www.elastic.co/elastic/docs-builder/docs/2454/solutions/observability/streams/management/data-quality
---

# Manage data quality
From the **Streams** page, use the **Data quality** menu to filter your streams by data quality status, then select a stream to examine it more closely. After selecting a stream, use the **Data quality** tab to find failed and degraded documents in your stream.
Use the following components to monitor the health of your data and identify and fix issues:
- **Degraded documents:** Documents from the last backing index of the stream with the `ignored` property, usually because of malformed fields or fields with values that exceed the configured `ignore_above` limit. This component shows:
  - Total number of degraded documents.
- Percentage of degraded documents relative to the total document count from the stream's last backing index.
- The data quality status (**Good**, **Degraded**, **Poor**).
- **Failed documents:** Documents that were rejected during ingestion because of mapping conflicts or pipeline failures. This component shows:
  - Total number of failed documents that correspond with this stream from within the specified time range in the date picker. Refer to [Failure store](#streams-data-quality-failure) for more information.
- Percentage of failed documents relative to the total document count from the stream's last backing index.
- The data quality status (**Good**, **Degraded**, **Poor**).
- **Quality score:** Streams calculates the overall quality score (**Good**, **Degraded**, **Poor**) based on the percentage of degraded and failed documents. Refer to [Data quality calculation](#streams-data-quality-calculation) for more information.
- **Trends over time:** A time-series chart so you can track how degraded and failed documents are accumulating over time. Use the date picker to focus on a specific range and understand when problems are spiking.
- `stack: preview 9.2` **Issues:** Find issues with specific fields, how often they've occurred, and when they've occurred.


## Data quality calculation

Streams calculates data quality as follows:
- **Good:** Both the **Degraded documents** percentage and the **Failed documents** percentage are 0.
- **Degraded:** Either the **Degraded documents** percentage or the **Failed documents** percentage are greater than 0 and less than or equal to 3.
- **Poor:** Either the **Degraded documents** percentage or the **Failed documents** percentage are greater than 3.


## Failure store

A [failure store](https://www.elastic.co/elastic/docs-builder/docs/2454/manage-data/data-store/data-streams/failure-store) is a secondary set of indices inside a data stream, dedicated to storing failed documents. Instead of losing documents that are rejected during ingestion, a failure store retains them in a `::failures` index, so you can review failed documents to understand what went wrong and how to fix it.
For example, for a stream called `my-stream`, Streams fetches all documents from the `my-stream::failures` index from within the specified time range in the date picker.

### Required permissions

To view and modify failure store in Elastic Stack, you need the following data stream level privileges:
- `read_failure_store`
- `manage_failure_store`

For more information, refer to [Granting privileges for data streams and aliases](https://www.elastic.co/elastic/docs-builder/docs/2454/deploy-manage/users-roles/cluster-or-deployment-auth/granting-privileges-for-data-streams-aliases).

### Turn on failure stores

In Streams, you need to turn on failure stores to get failed documents. To do this, select **Enable failure store** in the **Failed documents** component. From here you can set your failure store retention period.
For more information on data quality, refer to the [data set quality](https://www.elastic.co/elastic/docs-builder/docs/2454/solutions/observability/data-set-quality-monitoring) documentation.