what is the difference between freshness policy and automaterailize policy?

In Dagster, a FreshnessPolicy and an AutoMaterializePolicy serve different purposes when it comes to managing assets: 1. FreshnessPolicy: A FreshnessPolicy is used to define the expected update frequency of an asset. It specifies how up-to-date an asset should be by setting conditions such as

maximum_lag_minutes

. If an asset exceeds the specified lag time without being updated, it is considered "late" with respect to its FreshnessPolicy. This policy helps ensure that assets are updated within a certain timeframe to reflect the most recent data or changes. For example, if an asset has a FreshnessPolicy with

maximum_lag_minutes=60

, it means that the asset should be updated at least once every 60 minutes to meet the policy requirements. 2. AutoMaterializePolicy: An AutoMaterializePolicy, on the other hand, determines when an asset should be automatically materialized based on certain conditions. It can be configured to materialize assets based on various triggers, such as changes in upstream data, code changes, or to satisfy downstream freshness policies. The policy can be set to eagerly materialize assets when certain conditions are met, or to do so lazily, only when required by downstream consumers. In summary, a FreshnessPolicy is concerned with how frequently an asset should be updated to remain "fresh," while an AutoMaterializePolicy defines the conditions under which an asset should be automatically materialized without manual intervention. Both policies work together to automate and manage the lifecycle of assets in a Dagster pipeline.