How can I implement custom monitoring and alerting for specific events in my Delta Live Tables pipelines using event hooks?
To implement custom monitoring and alerting for specific events in your Delta Live Tables pipelines using event hooks, you can define custom Python callback functions that run when events are persisted to a Delta Live Tables pipeline’s event log. These functions are called event hooks.

Here are the steps to implement custom monitoring using event hooks:

1. Define a Python function that will be called when a specific event occurs. This function should take an `event` parameter, which contains information about the event.
2. Register the function as an event hook using the `register_event_hook` method of the `DeltaLiveTables` class. You can register multiple event hooks for different events.
3. When a specific event occurs, the registered event hook function will be called with the event object as a parameter. You can use this object to extract information about the event and implement custom monitoring and alerting.

Here's an example of how to define and register an event hook function that sends an email when a pipeline update fails:

```python
from deltalivetablesevent import DeltaLiveTablesEvent
from deltalivetablesevent import EventType
from deltalivetablesevent import EventSeverity
from deltalivetablesevent import EventSource
from deltalivetablesevent import EventStatus
from deltalivetablesevent import EventSubType
from deltalivetablesevent import EventTime
from deltalivetablesevent import EventUserData
from deltalivetablesevent import EventVersion
from deltalivetablesevent import register_event_hook

def send_email_on_failure(event: DeltaLiveTablesEvent):
    if event.event_type == EventType.PIPELINE_UPDATE_FAILED:
        # Extract information about the failed pipeline update
        pipeline_name = event.pipeline_name
        update_id = event.update_id
        error_message = event.error_message

        # Send an email with the information
        send_email(
            subject=f"Pipeline Update Failed: {pipeline_name}",
            body=f"Update ID: {update_id}\nError Message: {error_message}"
        )

# Register the event hook function
register_event_hook(send_email_on_failure)
```

In this example, the `send_email_on_failure` function is called when a pipeline update fails. The function extracts information about the failed pipeline update and sends an email with the information.

Note that event hooks are currently in public preview and may change in future releases.