How can I enable system table schemas in Databricks using the SystemSchemas API and grant access to them for users in my account?
To enable system table schemas in Databricks using the SystemSchemas API, you can follow these steps:

1. List available system schemas: Use the following curl command to list available system schemas:

```bash
curl -v -X GET -H "Authorization: Bearer <PAT Token>" "https://<workspace>.cloud.databricks.com/api/2.0/unity-catalog/metastores/<metastore-id>/systemschemas"
```

2. Enable a system schema: Use the following curl command to enable a system schema:

```bash
curl -v -X PUT -H "Authorization: Bearer <PAT Token>" "https://<workspace>.databricks.com/api/2.0/unity-catalog/metastores/<metastore-id>/systemschemas/<SCHEMA_NAME>"
```

If the system schema is enabled successfully, result code 200 is returned.

To grant access to system tables, you can follow these steps:

1. Grant USE and SELECT permissions on the system schemas: A metastore admin or other privileged user must grant these permissions to grant access to system tables. See Manage privileges in Unity Catalog for more information.

Note: System tables are read-only and cannot be modified.

Additionally, keep in mind the following considerations:

* System table access is governed by Unity Catalog.
* By default, no users have access to system tables.
* The audit log and lineage tables contain operational data for all workspaces in your account deployed within the same cloud region.
* The billing system table (system.billing.usage) contains data for all workspaces in your account, no matter what region they are deployed in.
* The system tables in your account are located in a catalog called system, which is included in every Unity Catalog metastore.
* During the system tables Public Preview, Databricks will retain all your system tables data.
* If your workspace uses a customer-managed VPC, you might be denied access to the S3 bucket where the logs are stored. If so, you need to update your VPC endpoint policy to allow access to the S3 bucket where your region’s system tables data is stored.
* The system schemas system.operational_data and system.lineage are deprecated and will contain empty tables.