[HBASE-8369] MapReduce over snapshot files

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.98.0
• Component/s: mapreduce, snapshots
• Hadoop Flags: Reviewed

Release Note

Added TableSnapshotInputFormat and TableSnapshotScanner for performing scans over hbase table snapshots from the client side, bypassing the hbase servers. The former configures a mapreduce job, while the latter does single client side scan over snapshot files. Can also be used with offline HBase with in-place or exported snapshot files.

WARNING: This feature bypasses HBase-level security completely since the files are read from the hdfs directly. The user who is running the scan / job has to have read permissions to the data files and snapshot files.

• Assignee: Enis Soztutar
• Reporter: Enis Soztutar
• Created: 17/Apr/13 22:28
• Updated: 20/Nov/15 11:52
• Resolved: 18/Nov/13 22:20

Description

The idea is to add an InputFormat, which can run the mapreduce job over snapshot files directly bypassing hbase server layer. The IF is similar in usage to TableInputFormat, taking a Scan object from the user, but instead of running from an online table, it runs from a table snapshot. We do one split per region in the snapshot, and open an HRegion inside the RecordReader. A RegionScanner is used internally for doing the scan without any HRegionServer bits.

Users have been asking and searching for ways to run MR jobs by reading directly from hfiles, so this allows new use cases if reading from stale data is ok:

• Take snapshots periodically, and run MR jobs only on snapshots.
• Export snapshots to remote hdfs cluster, run the MR jobs at that cluster without HBase cluster.
• (Future use case) Combine snapshot data with online hbase data: Scan from yesterday's snapshot, but read today's data from online hbase cluster.

Issue Links

• relates to: HBASE-10076 Backport MapReduce over snapshot files [0.94]

Sub-Tasks

• Backport parent issue to 0.96: Closed