Monitor columnar engine performance

This page describes how to monitor Spanner's columnar engine. You can monitor using:

• The query execution plan
• Storage usage graphs in system insights

View columnar data in the query plan

1. Run a query.
2. View its query plan.

3. In the Query summary section of the query execution, check for the Columnar read share information.

   The following image shows the Columnar read share percentage:

   

This metric shows the percentage of bytes read from columnar storage out of total bytes read from both row-based and columnar storage. A high percentage is optimal, while a low percentage suggests that much of the data remains unconverted to columnar format.

Columnar data storage metrics

To view columnar data storage metrics:

1. Go to the Spanner Instances page in the Google Cloud console.

   Go to the Instances page

2. Select the instance you want to view metrics for.

3. Click System insights.

4. In the Storage usage section, you can see two new metrics:

   columnar storage - hdd and columnar storage - ssd. These metrics show the columnar representation usage of HDD and SSD. The total storage metrics include both PAX and columnar data. You can see these metrics on storage usage graphs on the System insights page. For example:

   

What's next

• Learn about columnar engine.
• Learn how to enable columnar engine.
• Learn how to query columnar data.