Apache Kudu 1.14.0 Release Notes

Obsoletions

  • Support for CentOS 6/RHEL 6, Ubuntu 14, Ubuntu 16, and Debian 8 platforms has been dropped given they are at or near end-of-life. We will no longer validate these platforms as a part of the release process, though patches will still be accepted going forward.

  • Developer support for OS X 10.10 Yosemite, OS X 10.11 El Capitan, and OS X 10.12 Sierra has been dropped. We will no longer validate these versions as a part of the release process, though patches will still be accepted going forward.

Deprecations

  • Support for Python 2.x and Python 3.4 and earlier is deprecated and may be removed in the next minor release.

  • The kudu-mapreduce integration has been deprecated and may be removed in the next minor release. Similar functionality and capabilities now exist via the Apache Spark, Apache Hive, Apache Impala, and Apache NiFi integrations.

New features

  • Full support for INSERT_IGNORE, UPDATE_IGNORE, and DELETE_IGNORE operations was added. The INSERT_IGNORE operation will insert a row if one matching the key does not exist and ignore the operation if one already exists. The UPDATE_IGNORE operation will update the row if one matching the key exists and ignore the operation if one does not exist. The DELETE_IGNORE operation will delete the row if one matching the key exists and ignore the operation if one does not exist. These operations are particularly useful in situations where retries or duplicate operations could occur and you do not want to handle the errors that could result manually or you do not want to cause unnecessary writes and compaction work as a result of using the UPSERT operation. The Java client can check if the cluster it is communicating with supports these operations by calling the supportsIgnoreOperations() method on the KuduClient. See KUDU-1563 for more details.

  • Spark 3 compatible JARs compiled for Scala 2.12 are now published for the Kudu Spark integration. See KUDU-3202 for more details.

  • Every Kudu cluster now has an automatically generated cluster Id that can be used to uniquely identify a cluster. The cluster Id is shown in the masters web-UI, the kudu master list tool, and in master server logs. See KUDU-2574 for more details.

  • It is now possible to enforce that OpenSSL is initialized in FIPS approved mode in the servers and the C++ client by setting the KUDU_REQUIRE_FIPS_MODE environment variable to “1”, “yes” or “true”. See KUDU-3210 for more details.

Optimizations and improvements

  • Downloading the WAL data and data blocks when copying tablets to another tablet server is now parallelized, resulting in much faster tablet copy operations. These operations occur when recovering from a down tablet server or when running the cluster rebalancer. See KUDU-1728 and KUDU-3214 for more details.

  • The HMS integration now supports multiple Kudu clusters associated with a single HMS including Kudu clusters that do not have HMS synchronization enabled. This is possible, because the Kudu master will now leverage the cluster Id to ignore notifications from tables in a different cluster. Additionally, the HMS plugin will check if the Kudu cluster associated with a table has HMS synchronization enabled. See KUDU-3192 and KUDU-3187 for more details.

  • The HMS integration now supports gzipped HMS notifications. This is important in order to support Hive 4 where the default encoder was changed to be the GzipJSONMessageEncoder. See KUDU-3201 for more details.

  • Kudu will now fail tablet replicas that have been corrupted due to KUDU-2233 instead of crashing the tablet server. If a healthy majority still exists, a new replica will be created and the failed replica will be evicted and deleted. See KUDU-3191 and KUDU-2233 for more details.

  • DeltaMemStores will now be flushed as long as any DMS in a tablet is older than the point defined by --flush_threshold_secs, rather than flushing once every --flush_threshold_secs period. This can reduce memory pressure under update- or delete-heavy workloads, and lower tablet server restart times following such workloads. See KUDU-3195 for more details.

  • The kudu perf loadgen CLI tool now supports UPSERT for storing the generated data into the table. To switch to UPSERT for row operations (instead of default INSERT), add the --use_upsert command-line flag.

  • Users can now specify the level of parallelization when copying a tablet using the kudu local_replica copy_from_remote CLI tool by passing the --tablet_copy_download_threads_nums_per_session argument.

  • The Kudu Masters now discriminate between overlapped and exact duplicate key ranges when adding new partitions, returning Status::AlreadyPresent() for exact range duplicates and Status::InvalidArgument() for otherwise overlapped ones. In prior releases, the master returned Status::InvalidArgument() both in case of duplicate and otherwise overlapped ranges.

  • The handling of an empty list of master addresses in Kudu C++ client has improved. In prior releases, KuduClientBuilder::Build() would hang in ConnectToCluster() if no master addresses were provided. Now, KuduClientBuilder::Build() instantly returns Status::InvalidArgument() in such a case.

  • The connection negotiation timeout for Kudu C client is now programmatically configurable. To customize the connection negotiation timeout, use the newly introduced `KuduClientBuilder::connection_negotiation_timeout()` method in the Kudu C client API.

  • All RPC-related kudu CLI tools now have --negotiation_timeout_ms command line flag to control the client-side connection negotiation timeout. The default value for the new flag is set to 3000 milliseconds for backward compatibility. Keep in mind that the total RPC timeout includes the connection negotiation time, so in general it makes sense to bump --timeout_ms along with --negotiation_timeout_ms by the same delta.

  • Kudu now reports on slow SASL calls (i.e. calls taking more than 250 milliseconds to complete) when connecting to a server. This is to help diagnose issues like described in KUDU-3217.

  • MaintenanceManager now has a new histogram-based maintenance_op_find_best_candidate_duration metric to capture the stats on how long it takes (in microseconds) to find the best maintenance operation among available candidates. The newly introduced metric can help in diagnosing conditions where MaintenanceManager seems lagging behind the rate of write operations in a busy Kudu cluster with many replicas per tablet server.

  • The KuduScanToken Java API has been extended with a deserializeIntoScannerBuilder() method that can be used to further customize generated tokens.

  • Logging of the error message produced when applying an op while a Java KuduSession is closed has been throttled. See KUDU-3012 for more details.

  • Added a new uptime metric for a Kudu server. The metric’s value is reported as the length of the time interval passed from the start of the server, in microseconds. Knowing the server’s uptime, it’s easier to interpret and compare metrics reported by different Kudu servers.

  • Documentation for Kudu’s metrics are now automatically generated for each release and can be seen here.

Fixed Issues

  • Fixed lock contention between MaintenanceManager op registration and the scheduling of new maintenance ops. On particularly dense tablet servers, this contention was previously shown to significantly slow down startup times. See KUDU-3149 for more details.

  • Fixed lock contention between MaintenanceManager’s threads performing already scheduled operations and the scheduler thread itself. This benefits clusters with heavy ingest/update workloads that have many replicas per tablet server. See KUDU-1954 for more details.

  • Fixed a bug in the merge iterator that could result in a crash. This could surface as a crash when performing ordered or differential scans, particularly when the underlying data contained deletes and reinserts. See KUDU-3108 for more details.

  • Fixed a heap-use-after-free bug in Kudu C++ client that might manifest itself when altering a table to update the partitioning schema. See KUDU-3238 for more details.

  • Fixed a bug where building scan tokens would result in a NullPointerException if a tablet not found error occurred before generating the token. See KUDU-3205 for more details.

  • Fixed a bug where a delete operation would fail if the row being deleted contained exactly 64 columns and all values were set on the row. See KUDU-3198 for more details.

  • Fixed a bug where Slf4j classes were shaded into the Spark integration JARs. See KUDU-3157 for more details.

  • Fixed a bug where the 'kudu hms fix' tool mistakenly reports non-matching master addresses when the addresses are in-fact canonically the same. See KUDU-2884 for more details.

Wire Protocol compatibility

Kudu 1.14.0 is wire-compatible with previous versions of Kudu:

  • Kudu 1.14 clients may connect to servers running Kudu 1.0 or later. If the client uses features that are not available on the target server, an error will be returned.

  • Rolling upgrade between Kudu 1.13 and Kudu 1.14 servers is believed to be possible though has not been sufficiently tested. Users are encouraged to shut down all nodes in the cluster, upgrade the software, and then restart the daemons on the new version.

  • Kudu 1.0 clients may connect to servers running Kudu 1.14 with the exception of the below-mentioned restrictions regarding secure clusters.

The authentication features introduced in Kudu 1.3 place the following limitations on wire compatibility between Kudu 1.14 and versions earlier than 1.3:

  • If a Kudu 1.14 cluster is configured with authentication or encryption set to "required", clients older than Kudu 1.3 will be unable to connect.

  • If a Kudu 1.14 cluster is configured with authentication and encryption set to "optional" or "disabled", older clients will still be able to connect.

Incompatible Changes in Kudu 1.14.0

Client Library Compatibility

  • The Kudu 1.14 Java client library is API- and ABI-compatible with Kudu 1.13. Applications written against Kudu 1.13 will compile and run against the Kudu 1.14 client library and vice-versa.

  • The Kudu 1.14 C++ client is API- and ABI-forward-compatible with Kudu 1.13. Applications written and compiled against the Kudu 1.13 client library will run without modification against the Kudu 1.14 client library. Applications written and compiled against the Kudu 1.14 client library will run without modification against the Kudu 1.13 client library.

  • The Kudu 1.14 Python client is API-compatible with Kudu 1.13. Applications written against Kudu 1.13 will continue to run against the Kudu 1.14 client and vice-versa.

Known Issues and Limitations

Please refer to the Known Issues and Limitations section of the documentation.

Contributors

Kudu 1.14.0 includes contributions from 12 people, including 1 first-time contributors:

  • liguohao

Thank you for your contributions!

Installation Options

For full installation details, see Kudu Installation.