This page describes the Cloud SQL for MySQL index advisor and how you can view
and apply its index recommendations.

Cloud SQL for MySQL offers a fully managed index advisor that tracks the
queries your database handles regularly. Periodically, the index advisor
analyzes these queries to recommend new indexes that can improve query
performance. The index advisor lets you detect and fix performance
issues with systems and queries.

## How does the index advisor work?

The index advisor helps you improve query processing by
doing the following:

- Recommend a set of indexes with SQL commands to create indexes.
- Provide data to help you evaluate recommended indexes, for example, estimated storage size and impact of indexes on a query.

The index advisor stores and displays the `CREATE INDEX` command containing the database name, table name, and column names. The tracked queries are all normalized queries with all literals removed.

Index recommendations are encrypted at rest.
In Cloud SQL for MySQL, you can use database flags to configure and tune the index advisor. For more information, see [Index advisor flags](https://docs.cloud.google.com/sql/docs/mysql/flags.md.txt#index-advisor-flags).

## Limitations

Cloud SQL for MySQL index advisor has the following limitations:

- The index advisor provides `CREATE INDEX` recommendations only.
- The index advisor doesn't support instances with the following configurations:
  - Cloud SQL Enterprise edition instances
  - Instances that use shared-core machine types

## Before you begin

To obtain index advisor recommendations,
you must use Cloud SQL Enterprise Plus edition and enable
[query insights for Cloud SQL Enterprise Plus edition](https://docs.cloud.google.com/sql/docs/mysql/using-query-insights.md.txt#enable-enterprise-plus-query-insights)
for your Cloud SQL instance.

### Required roles and permissions


To get the permissions that
you need to obtain index advisor recommendations,

ask your administrator to grant you the
[Cloud SQL Viewer](https://docs.cloud.google.com/iam/docs/roles-permissions/cloudsql.md.txt#cloudsql.viewer) (`roles/cloudsql.viewer`) IAM role on the project that hosts the Cloud SQL instance.


For more information about granting roles, see [Manage access to projects, folders, and organizations](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access.md.txt).


This predefined role contains

the permissions required to obtain index advisor recommendations. To see the exact permissions that are
required, expand the **Required permissions** section:


#### Required permissions

The following permissions are required to obtain index advisor recommendations:

- `databaseinsights.recommendations.query`
- `databaseinsights.resourceRecommendations.query`


You might also be able to get
these permissions
with [custom roles](https://docs.cloud.google.com/iam/docs/creating-custom-roles.md.txt) or
other [predefined roles](https://docs.cloud.google.com/iam/docs/roles-overview.md.txt#predefined).

<br />

## Enable index advisor recommendations

When you [enable query insights for Cloud SQL Enterprise Plus edition](https://docs.cloud.google.com/sql/docs/mysql/using-query-insights.md.txt#enable-insights),
you enable index advisor recommendations automatically. For more information regarding restart requirements, see [Enable query insights](https://docs.cloud.google.com/sql/docs/mysql/using-query-insights.md.txt#enable-insights).

## Disable index advisor recommendations

You can't disable index advisor recommendations without disabling query insights for Cloud SQL Enterprise Plus edition.

To disable index advisor recommendations and query insights for Cloud SQL Enterprise Plus edition, see
[Disable query insights for Cloud SQL Enterprise Plus edition](https://docs.cloud.google.com/sql/docs/mysql/using-query-insights.md.txt#disable-enterprise-query-insights).

## View index advisor recommendations

Cloud SQL automatically runs the index advisor analysis
periodically. To view index advisor recommendations, use the Query insights dashboard.

You can also view and query the index advisor recommendations as a table or request
an on-demand analysis and report at any time.


### View and filter recommendations in the Query insights dashboard

1. In the Google Cloud console, go to the **Cloud SQL Instances** page.

   [Go to Cloud SQL Instances](https://console.cloud.google.com/sql)
2. To open the **Overview** page of an instance, click the instance name.
3. Click **Query insights**.
4. The index advisor recommendations are displayed in the **Recommendation** column of the **Top queries and tags** section.
5. Optional: To view only the queries with `CREATE INDEX` recommendations, add a filter for **Recommendation: Create Indexes**.

### View recommendations for a query

To view index recommendations for a specific query, follow these
steps:

1. In the Google Cloud console, go to the **Cloud SQL Instances** page.

   [Go to Cloud SQL Instances](https://console.cloud.google.com/sql)
2. To open the **Overview** page of an instance, click the instance name.
3. Click **Query insights**.
4. In the **Top queries and tags** section, click **Queries**.
5. To get recommendation details for a query, do one of the following:
   - Click a query to learn more about the recommendations for the selected query, including the following information:
     - **Performance impact** (high, medium, and low): The estimated query speed after all recommended indexes are created.
     - **Recommendations**: Create index recommendations.
     - **Tables impacted**: The number of tables that will be impacted when indexes are created.
     - **Additional estimated storage needed**: The estimated storage size needed to create all the recommended indexes.
     - **Number of impacted queries**: The total number of queries in the workload impacted by the index recommendations. An index can benefit multiple queries.
   - Click **Create Indexes** for a specific query to learn detailed recommendations about creating indexes to improve query performance.

### View recommendations as a database table view

You can read its results through the following table located in the `mysql`
database:

- `mysql.cloudsql_db_advisor_recommended_indexes`: lists any recommended new indexes for each database. It also includes estimates of the storage required for each index, and the number of queries that each index can affect.

For example, to see the results of the most recent index-recommendation
analysis, formatted as a table, run this query:

```sql
SELECT * FROM mysql.cloudsql_db_advisor_recommended_indexes;
```

## Create recommended indexes

You can create recommended indexes from the Query insights dashboard or
from a database table view.

### Create a recommended index using the Query insights dashboard

To create a recommended index using the Query insights dashboard, do the
following:

1. In the Google Cloud console, go to the **Cloud SQL Instances** page.

   [Go to Cloud SQL Instances](https://console.cloud.google.com/sql)
2. To open the **Overview** page of an instance, click the instance name.
3. Click **Query insights**.
4. In the **Top dimensions by database load** table, click **Queries**.
5. Click **Create Indexes** for a specific query.
6. Click **Copy all index commands** . The `CREATE INDEX` commands are copied to your clipboard.
7. Connect to the primary instance on the command line.
8. To create the recommended indexes, run the commands that were copied to
   your clipboard, for example:

   ```sql
   CREATE INDEX ON "public"."demo_order" ("customer_id");
   ```

### Create a recommended index using a database table view

The `index` column of the `mysql.cloudsql_db_advisor_recommended_indexes` table
contains, in each row, a complete MySQL `CREATE INDEX` DDL
statement for generating the index recommended in that row.

To apply that row's recommendation, run that DDL statement, exactly as
presented.

For example, consider this output from manually running an analysis,
using the query described in the previous section:

                        index                   | estimated_storage_size_in_mb
    ---+---
     CREATE INDEX ON "School"."Students"("age") |                            3
    (1 row)

This report contains a single recommendation: adding a single-column
index on the `age` column in the `School` schema's `Students`
table. To apply this advice, enter a DDL query as
represented within the report:

```sql
CREATE INDEX ON "School"."Students"("age");
```

## View impacted queries

1. In the Google Cloud console, go to the **Cloud SQL Instances** page.

   [Go to Cloud SQL Instances](https://console.cloud.google.com/sql)
2. To open the **Overview** page of an instance, click the instance name.
3. Click **Query insights**.
4. In the **Top dimensions by database load** table, click **Queries**.
5. Click **Create indexes** for a specific query.
6. Click **Show impacted queries**.
7. Click a query to learn details about the impacted query.

## Configure the index advisor

While the index advisor is designed to work for most use cases with its
default settings, you can fine-tune its behavior by setting various
database flags.

By default, index advisor runs once every 24 hours. You can modify the
autoschedule time using the
[`cloudsql_index_advisor_auto_advisor_schedule`](https://docs.cloud.google.com/sql/docs/mysql/flags.md.txt#index-advisor-flags)
flag, or run an ad hoc analysis on a specific
date/time using the
[`cloudsql_index_advisor_run_at_timestamp`](https://docs.cloud.google.com/sql/docs/mysql/flags.md.txt#index-advisor-flags) flag.
For more information, see
[Index advisor flags](https://docs.cloud.google.com/sql/docs/mysql/flags.md.txt#index-advisor-flags).

## What's next

- [Use query insights](https://docs.cloud.google.com/sql/docs/mysql/using-query-insights.md.txt)