jroachgolf84 commented on code in PR #67299: URL: https://github.com/apache/airflow/pull/67299#discussion_r3357082429
########## airflow-core/docs/core-concepts/task-and-asset-store.rst: ########## @@ -0,0 +1,80 @@ + .. Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + .. http://www.apache.org/licenses/LICENSE-2.0 + + .. Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. + +.. _concepts:task-and-asset-store-overview: + +Task and Asset Store Overview +============================= + +.. versionadded:: 3.3 + +Airflow has always modeled tasks as stateless, idempotent units of work. A growing class of workloads, however, require a small amount of data to be persisted outside of a Task's return value, like a submitted job ID that must survive a worker crash, a watermark that advances run-by-run, or a row counter exposed for observability. Task store and Asset store fill that gap without touching the XCom or Variable systems. + +Task and Asset Store +-------------------- + +Airflow 3.3 ships two persistent key/value stores, differentiated by *what* they are scoped to: + +.. list-table:: + :header-rows: 1 + :widths: 20 25 25 30 + + * - Store + - Scope + - Default lifetime + - Primary use case + * - **Task store** + - A single task Instance (dag_id + run_id + task_id + map_index) + - Configurable retention; cleared on task success when ``clear_on_success = True`` + - Survive retries, track in-flight jobs, checkpoint progress within a run, resume progress from checkpoint set by a past run + * - **Asset store** + - An asset (independent of any particular run) + - Persists indefinitely; removed only when the asset is deactivated + - Cross-run watermarks, incremental-load cursors, per-asset metadata + +Both stores accept string keys and JSON values. Values up to 64 KB are supported through the default metastore backend; larger payloads can be offloaded via a :ref:`custom worker-side backend <task-and-asset-store:worker-backends>`. + +When to use Task and Asset Store +-------------------------------- + +Use this table to choose the right mechanism for your use case. + +.. list-table:: + :header-rows: 1 + :widths: 22 78 + + * - Mechanism + - When to use it + * - **XCom** + - Pass data *between tasks* within a single Dag run (e.g. the output of one task consumed by a downstream task) or across different multiple Dag runs (referencing the data persisted from another run). XComs are cleared on retry, and should NOT be used to persist data across task retries or across runs. + * - **Variables** + - Dag-wide or installation-wide configuration that changes infrequently and is set by operators rather than by tasks themselves. Review Comment: Updated in next commit. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
