Apache Accumulo 1.7.4

23 Mar 2018

Apache Accumulo 1.7.4 is a maintenance release on the 1.7 version branch. This release contains changes from 46 issues, comprised of bug-fixes, performance improvements, build quality improvements, and more. See Jira or the bottom of this page for a complete list.

Below are resources for this release:

  • User Manual - In-depth developer and administrator documentation.
  • Javadocs - Accumulo 1.7.4 API
  • Examples - Code with corresponding readme files that give step by step instructions for running example code.

Accumulo follows Semantic Versioning guidelines. This release is a “patch version”, which means that only backwards compatible bug fixes are introduced in this version. A bug fix is defined as an internal change that fixes incorrect behavior. Users of any previous 1.7.x release are strongly encouraged to update as soon as possible to benefit from the bug fixes with very little concern in change of underlying functionality. As always, the Accumulo developers take API compatibility very seriously and have invested much time to ensure that we meet the promises set forth to our users. Users of 1.6 or earlier that are seeking to upgrade to 1.7 should consider 1.7.4 as a starting point.

Major Changes

Fixed upgrade process to set version on all volumes

During upgrades, only one volume in a multiple HDFS volume was updated with the correct version. This would cause all tablet servers to complain and ultimately fail. ACCUMULO-4686 fixes this by setting the version on all volumes.

Updated Accumulo to work with new releases of Guava

In ACCUMULO-4702, dependencies on Beta-annotated Guava classes and methods were removed. While Accumulo still includes Guava 14 in its tarball, it will work with newer versions of Guava in client code. It has been tested to work with Guava 23.

Updated RFile to prevent very large blocks

RFiles now use windowed statistics (ACCUMULO-4669) to prevent very large blocks. In 1.7.3 a bug was introduced that caused RFile data block sizes to grow very large in the case where key sizes slowly increased. This could lead to degraded query performance or out of memory exceptions on tablet servers.

Notable Changes


View the Upgrading Accumulo documentation for guidance.


Continuous ingest, random walk, and all integration test were run against RC0. A few bugs were found and fixed before RC1. Randomwalk was run overnight with 4 walkers. Continuous ingest was run with 9 nodes for 22 hours followed by a successful verification. A Kerberos IT failed because the 1.7.4 pom depends on Hadoop 2.2.0, the IT passed with a newer version of Hadoop.

All Changes

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