Refreshing materialized Snowflake views on schedule

Question

Pulumi · Accepted Answer

In order to refresh materialized Snowflake views on a schedule using Pulumi and the Snowflake provider, we will utilize the `snowflake.Task` resource. This resource allows you to define a task in Snowflake that can execute on a defined schedule. The task will contain an SQL statement that refreshes a specified materialized view.

Here's a step-by-step explanation of the process, followed by the Pulumi program written in TypeScript:

1. **Define a Snowflake Task**: A task is an object in Snowflake that allows you to schedule the execution of SQL statements. For materialized views, the SQL statement will typically be a `REFRESH MATERIALIZED VIEW` command.
2. **Set a Schedule**: Snowflake tasks can be scheduled using CRON expressions to execute at regular time intervals, such as every hour or once a day.

Here is a Pulumi program that creates a task in Snowflake to refresh a materialized view every day at midnight:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as snowflake from "@pulumi/snowflake";

const refreshMaterializedViewTask = new snowflake.Task("refreshMaterializedViewTask", {
    // The database and schema in which the task is created and the materialized view resides.
    database: "your_database",
    schema: "your_schema",
    // Descriptive name for the task.
    name: "refresh_daily_mv",
    // SQL statement to execute, here it refreshes a materialized view named 'your_materialized_view'.
    sqlStatement: "REFRESH MATERIALIZED VIEW your_schema.your_materialized_view",
    // CRON schedule to refresh the view every day at midnight. Make sure to adjust the CRON expression to match your desired schedule.
    schedule: "USING CRON 0 0 * * * UTC",
});

// Export the task's name
export const taskName = refreshMaterializedViewTask.name;
```

In this program:
- We import the needed modules from Pulumi and the Snowflake provider.
- We create a new `Task` resource named `refreshMaterializedViewTask`.
- We specify the database and schema names where the task and materialized view are located.
- We provide a name for the task, an SQL statement to execute, and a schedule for the task. The `sqlStatement` is set to refresh a materialized view with the name `your_materialized_view`. Make sure to replace `your_database`, `your_schema`, and `your_materialized_view` with the actual names from your Snowflake instance.
- We set the `schedule` in CRON format to execute the task every day at midnight UTC. You can adjust the CRON expression according to your specific scheduling needs.
- We export the task's name which can be used to reference the task in future Pulumi operations.

For more information on working with Snowflake tasks and CRON schedules, you can refer to the Snowflake documentation:

- [Snowflake Tasks Documentation](https://docs.snowflake.com/en/sql-reference/sql/create-task.html)
- [CRON Scheduler Documentation](https://docs.snowflake.com/en/user-guide/tasks-intro.html#task-scheduling)

Make sure to replace placeholders like `your_database`, `your_schema`, and `your_materialized_view` with your actual Snowflake identifiers. You would also need to have the `@pulumi/snowflake` package installed and Snowflake provider configured appropriately with access rights to manage tasks and materialized views.