@albertshau albertshau released this Mar 24, 2015 · 22558 commits to develop since this release

Assets 2


  • The HTTP RESTful API v2 is deprecated, replaced with the namespaced HTTP RESTful API v3.
  • Added log rotation for CDAP programs running in YARN containers (CDAP-1295).
  • Added the ability to submit to non-default YARN queues to provide resource guarantees for CDAP Master Services, CDAP Programs, and Explore Queries (CDAP-1417).
  • Added the ability to prune invalid transactions (CDAP-1540).
  • Added the ability to specific custom logback file for CDAP programs (CDAP-1100).
  • System HTTP services now bind to all interfaces (, rather than

New Features

  • Command Line Interface (CLI)
    • CLI can now directly connect to a CDAP instance of your choice at startup by using cdap-cli.sh --uri <uri>.
    • Support for runtime arguments, which can be listed by running "cdap-cli.sh --help".
    • Table rendering can be configured using "cli render as <alt|csv>".
      The option "alt" is the default, with "csv" available for copy & pasting.
    • Stream statistics can be computed using "get stream-stats <stream-id>".
  • Datasets
    • Added an ObjectMappedTable Dataset that maps object fields to table columns and that is also explorable.
    • Added a PartitionedFileSet Dataset that allows addressing files by meta data and that is also explorable.
    • Table Datasets now support a multi-get operation for batched reads.
    • Allow an unchecked Dataset upgrade upon application deployment
  • Metrics
    • Added new APIs for exploring available metrics, including drilling down into the context of emitted metrics
    • Added the ability to explore (search) all metrics; previously, this was restricted to custom user metrics
    • There are new APIs for querying metrics
    • New capability to break down a metrics time series using the values of one or more tags in its context
  • Namespaces
    • Applications and Programs are now managed within namespaces.
    • Application logs are available within namespaces.
    • Metrics are now collected and queried within namespaces.
    • Datasets can now created and managed within namespaces.
    • Streams are now namespaced for ingestion, fetching, and consuming by programs.
    • Explore operations are now namespaced.
  • Preferences
    • Users can store preferences (a property map) at the instance, namespace, application, or program level.
  • Spark
    • Spark now uses a configurer-style API for specifying (CDAP-382).
  • Workflows
    • Users can schedule a Workflow based on increments of data being ingested into a Stream.
    • Workflows can be stopped.
    • The execution of a Workflow can be forked into parallelized branches.
    • The runtime arguments for Workflow can be scoped.
  • Workers
    • Added Worker, a new Program type that can be added to CDAP Applications, used to run background processes and (beta feature) can write to Streams through the WorkerContext.
  • Upgrade and Data Migration Tool
    • Added an automated upgrade tool which supports upgrading from 2.6.x to 2.8.0. (Note: Apps need to be both recompiled and re-deployed). Upgrade from 2.7.x to 2.8.0 is not currently supported. If you have a use case for it, please reach out to us at cdap-user@googlegroups.com.
    • Added a metric migration tool which migrates old metrics to the new 2.8 format.


  • Improved Flow performance and scalability with a new distributed queue implementation.

API Changes

  • The endpoint (GET <base-url>/data/explore/datasets/<dataset-name>/schema) that retrieved the schema of a Dataset's underlying Hive table has been removed (CDAP-1603).
  • Endpoints have been added to retrieve the CDAP version and the current configurations of CDAP and HBase.

Known Issues

  • If the Hive Metastore is restarted while the CDAP Explore Service is running, the Explore Service remains alive, but becomes unusable. To correct, restart the CDAP Master, which will restart all services (CDAP-1007).

  • User datasets with names starting with "system" can potentially cause conflicts (CDAP-1587).

  • Scaling the number of metrics processor instances doesn't automatically distribute the processing load to the newer instances of the metrics processor. The CDAP Master needs to be restarted to effectively distribute the processing across all metrics processor instances (CDAP-1853).

  • Creating a dataset in a non-existent namespace manifests in the RESTful API with an incorrect error message (CDAP-1864).

  • Retrieving multiple metrics |---| by issuing an HTTP POST request with a JSON list as the request body that enumerates the name and attributes for each metric |---| is currently not supported in the Metrics HTTP RESTful API v3. Instead, use the v2 API. It will be supported in a future release.

  • Typically, Datasets are bundled as part of Applications. When an Application is upgraded and redeployed, any changes in Datasets will not be redeployed. This is because Datasets can be shared across applications, and an incompatible schema change can break other applications that are using the Dataset. A workaround (CDAP-1253) is to allow unchecked Dataset upgrades. Upgrades cause the Dataset metadata, i.e. its specification including properties, to be updated. The Dataset runtime code is also updated. To prevent data loss the existing data and the underlying HBase tables remain as-is.

    You can allow unchecked Dataset upgrades by setting the configuration property dataset.unchecked.upgrade to true in cdap-site.xml. This will ensure that Datasets are upgraded when the Application is redeployed. When this configuration is set, the recommended process to deploy an upgraded Dataset is to first stop all Applications that are using the Dataset before deploying the new version of the Application. This lets all containers (Flows, Services, etc) to pick up the new Dataset changes. When Datasets are upgraded using dataset.unchecked.upgrade, no schema compatibility checks are performed by the system. Hence it is very important that the developer verify the backward-compatibility, and makes sure that other Applications that are using the Dataset can work with the new changes.