Repository: accumulo Updated Branches: refs/heads/gh-pages 535d261ed -> e5d6cc243
Updates for 1.8.0 release notes Project: http://git-wip-us.apache.org/repos/asf/accumulo/repo Commit: http://git-wip-us.apache.org/repos/asf/accumulo/commit/e5d6cc24 Tree: http://git-wip-us.apache.org/repos/asf/accumulo/tree/e5d6cc24 Diff: http://git-wip-us.apache.org/repos/asf/accumulo/diff/e5d6cc24 Branch: refs/heads/gh-pages Commit: e5d6cc24322a8b119147d2dedf40585584cd6b94 Parents: 535d261 Author: Michael Wall <mjw...@gmail.com> Authored: Tue Sep 6 16:57:05 2016 -0400 Committer: Michael Wall <mjw...@gmail.com> Committed: Tue Sep 6 16:57:05 2016 -0400 ---------------------------------------------------------------------- release_notes/1.8.0.md | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/accumulo/blob/e5d6cc24/release_notes/1.8.0.md ---------------------------------------------------------------------- diff --git a/release_notes/1.8.0.md b/release_notes/1.8.0.md index 979bfa0..de21e13 100644 --- a/release_notes/1.8.0.md +++ b/release_notes/1.8.0.md @@ -22,23 +22,28 @@ very seriously and have invested much time to ensure that we meet the promises s ### Speed up WAL roll overs -By creating active and standby Write-Ahead Log (WAL) files, switching to a new WAL is simplified to an atomic -reference switch of the WAL writer objects. This was a substantial refactor -in they way WALs worked, but smoothes overal ingest performance in addition to provides a increase in write speed -as shown by the simple test below. The top entry is before [ACCUMULO-3423][ACCUMULO-3423] and the bottom graph is after the refactor. +Performance of writing mutations is improved by refactoring the +bookeeping required for Write-Ahead Log (WAL) files and by creating a +standby WAL for faster switching when the log is full. This was a +substantial refactor in the way WALs worked, but smoothes overall +ingest performance in addition to provides a increase in write speed +as shown by the simple test below. The top entry is before +[ACCUMULO-3423][ACCUMULO-3423] and the bottom graph is after the +refactor. ![Graph of WAL speed up after ACCUMULO-3423][IMG-3423] ### User level API for RFile Previously the only public API available to write RFiles was via the AccumuloFileOutputFormat. There was no way to read RFiles in the public -API. [ACCUMULO-4165][ACCUMULO-4165] exposes a brand new public API for reading and writing RFiles as well as cleans up some of the internal APIs. +API. [ACCUMULO-4165][ACCUMULO-4165] exposes a brand new public [API][RFILE_API] for reading and writing RFiles as well as cleans up some of the internal APIs. ### Suspend Tablet assignment for rolling restarts When a tablet server dies, Accumulo attempted to reassign the tablets as quickly as possible to maintain availability. A new configuration property `table.suspend.duration` (with a default of zero seconds) now controls how long to wait before reassigning -a tablet from a dead tserver. The property is configurable in Zookeeper, so you can set it, do a rolling restart, and then +a tablet from a dead tserver. The property is configurable via the +Accumulo shell, so you can set it, do a rolling restart, and then set it back to 0. A new state as introduced, TableState.SUSPENDED to support this feature. By default, metadata tablet reassignment is not suspended, but that can also be changed with the `master.metadata.suspendable` property that is false by default. Root tablet assignment can not be suspended. See [ACCUMULO-4353] for more info. @@ -58,12 +63,15 @@ names do not change if this feature is not used. ### Rate limiting Major Compactions -Major Compactions can significantly increase the amount of load on TabletServers. [ACCUMULO-4187] takes a cue from Apache -Cassandra and restricts the rate at which data is read and written when performing major compactions. This has a direct effect -on the IO load caused by major compactions with a similar effect on the CPU utilization. This behavior is controlled -by a new property `tserver.compaction.major.throughput` with a defaults of 0B which disables the rate limiting. +Major Compactions can significantly increase the amount of load on +TabletServers. [ACCUMULO-4187] restricts the rate at which data is +read and written when performing major compactions. This has a direct +effect on the IO load caused by major compactions with a similar +effect on the CPU utilization. This behavior is controlled by a new +property `tserver.compaction.major.throughput` with a defaults of 0B +which disables the rate limiting. -### Sampling +### Table Sampling Queryable sample data was added by [ACCUMULO-3913]. This allows users to configure a pluggable function to generate sample data. At scan time, the sample data can optionally be scanned. @@ -169,5 +177,6 @@ HDFS High-Availability instances, forcing NameNode failover. [THRIFT-0.9.3-RN]: https://github.com/apache/thrift/blob/0.9.3/CHANGES [api]: https://github.com/apache/accumulo/blob/1.8/README.md#api [semver]: http://semver.org -[sample]: http://accumulo.apache.org/1.8/examples/sample +[sample]: ../1.8/examples/sample [ITER_TEST]: https://accumulo.apache.org/1.8/accumulo_user_manual.html#_iterator_testing +[RFILE_API]: ../1.8/apidocs/org/apache/accumulo/core/client/rfile/RFileWriter.html
