Add Monitoring Clustering Costs section

Ideally, `average_overlaps` would be below 1 and `average_depth` would be ~ 1. A high number indicates the table is not well clustered.

### Monitoring Clustering Costs

To monitor the cost and activity of automatic clustering, query the `automatic_clustering_history` table, here's an example query:

```sql

SELECT 

    start_time,

    end_time,

    table_name,

    schema_name,

    database_name,

    credits_used,

    num_bytes_reclustered,

    num_rows_reclustered,

    DATEDIFF('minute', start_time, end_time) AS duration_minutes

FROM snowflake.account_usage.automatic_clustering_history

WHERE table_name = 'FCT_BEHAVIOR_STRUCTURED_EVENT'  -- Replace with your table name

    AND schema_name = 'COMMON'                       -- Replace with your schema

    AND database_name = 'PROD'                       -- Replace with your database

    AND start_time >= '2025-12-17'                   -- When clustering was enabled

ORDER BY start_time DESC;

```

Key Metrics:

`credits_used`: Snowflake credits consumed by automatic clustering operations

`num_bytes_reclustered`: Amount of data reorganized (in bytes)

`num_rows_reclustered`: Number of rows reorganized

`duration_minutes`: How long the clustering operation took

## Best Practices

1. Choose clustering keys wisely based on your query patterns