v0.3.0

Release Version 0.3.0
[0.3.0] - 2022-08-17
Added

• The data transfer module now supports any combination of H2 and Apache Spark
  as client and server. Apache Spark uses distributed Receivers run by Workers.
• The configuration file parser now also supports inline comments and emits
  errors that contain information about which settings are missing arguments.
• Improved messages from predicate push-down when a predicate is not supported.
• External tables can be added to Apache Spark with modelardb.spark.external.

Changed

• The Apache Arrow Flight-based query interface now transfers data in batches.
• Reverted to the key-value configuration file format and removed PureConfig.
  The data transfer module is configured with the modelardb.transfer setting.
• The value of modelardb.dynamic_split_fraction is now used directly as set.
• Renamed gaps in the Segment View to offsets for both Apache Spark and H2.
• Renamed mid to mtid in ORCStorage and ParquetStorage for consistency.

Removed

• Dropped Akka Streams from the data transfer module and switched to using
  Apache Arrow Flight directly for data transfer.

Fixed

• H2 adding parentheses to CQL WHERE clauses and not appending ALLOW FILTERING.
• Fix ModelType.withinErrorBound() never returning true with error bound zero.
• Fix Apache Spark using the wrong case for predicate push-down of members.
• Fix the denormalized dimensions using the wrong case for the column names.

v0.2.0

Release Version 0.2.0
[0.2.0] - 2021-12-21
Added

• A storage layer that use Apache Parquet or Apache ORC as the on-disk format.
• Support for specifying a different port for the HTTP and Socket interfaces
  using the syntax interface:port. The port 9999 is still used by default.
• Integration tests that ensure engines and data stores return the same result.
• An experimental configuration file format based on PureConfig and HOCON.
• A prototype transfer module based on Akka Streams and Apache Arrow Flight.
• A binary column-based query interface that is based on Apache Arrow Flight.

Changed

• The Apache Spark-based engine now uses INT64 for the timestamps when storing
  segments in Apache Parquet files for compatibility with the H2-based engine.
• Both engines now use the same format when serializing timestamps to JSON.

Fixed

• Some numbers being quoted in the JSON output from the H2-based engine.
• The Apache Spark-based engine swapping tid and mtid for one projection.

NOTE: This release has been recreated to correct a problem in the Git history. The source code remains unchanged compared to the original release of version 0.2.0.

v0.1.0

Release Version 0.1.0
[0.1.0] - 2021-09-02
Added

• A query engine for single-node deployments based on the RDBMS H2.
• Support for executing queries from multiple users in parallel when using the
  socket and HTTP interface.
• All UDFs and UDAFs in the Segment View now support the # operator, in
  contrast to * it selects only the columns required for a UDAF or UDF.
• Support for creating queryable derived time series as a source time series and
  a function defined as transform(value: Float, scalingFactor: Float): Float.
• Support for ingesting time series from Apache Parquet and Apache ORC.

Changed

• The configuration file now defaults to $HOME/.modelardb.conf.
• Improved names of parameters in the configuration file.
• The timezone in the configuration is set as the default so it is always used.
• Changed the column names in the views to match internal terminology.
• The UDF INTERVAL in the Segment View has been renamed to START_END.

Removed

• SQLite is no longer included as it is replaced by H2.
• The _SS UDAFs have been removed as they are not needed for H2 and can be
  replaced with INLINE and a sub-query for Apache Spark.
• The Spark Cassandra Connector is no longer included in the uber Jar.