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Before this change, Cleaner performs cleaning of old file versions and then stores the deleted files in .clean files. With this setup, we will not be able to track file deletions if a cleaner fails after deleting files but before writing .clean metadata. This is fine for regular file-system view generation but Incremental timeline syncing relies on clean/commit/compaction metadata to keep a consistent file-system view. Cleaner state transitions is now similar to that of compaction. 1. Requested : HoodieWriteClient.scheduleClean() selects the list of files that needs to be deleted and stores them in metadata 2. Inflight : HoodieWriteClient marks the state to be inflight before it starts deleting 3. Completed : HoodieWriteClient marks the state after completing the deletion according to the cleaner plan
Hudi
Apache Hudi (Incubating) (pronounced Hoodie) stands for Hadoop Upserts Deletes and Incrementals.
Hudi manages the storage of large analytical datasets on DFS (Cloud stores, HDFS or any Hadoop FileSystem compatible storage).
Features
- Upsert support with fast, pluggable indexing
- Atomically publish data with rollback support
- Snapshot isolation between writer & queries
- Savepoints for data recovery
- Manages file sizes, layout using statistics
- Async compaction of row & columnar data
- Timeline metadata to track lineage
Hudi provides the ability to query via three types of views:
- Read Optimized View - Provides excellent snapshot query performance via purely columnar storage (e.g. Parquet)
- Incremental View - Provides a change stream with records inserted or updated after a point in time.
- Real-time View - Provides snapshot queries on real-time data, using a combination of columnar & row-based storage (e.g Parquet + Avro)
Learn more about Hudi at https://hudi.apache.org
Building Apache Hudi from source
Hudi requires Java 8 to be installed on a *nix system. Check out code and normally build the maven project, from command line:
# Checkout code and build
git clone https://github.com/apache/incubator-hudi.git && cd incubator-hudi
mvn clean package -DskipTests -DskipITs
Quickstart
Try https://hudi.apache.org/quickstart.html to quickly explore Hudi's capabilities using spark-shell.