Github user bhavya411 commented on the issue:
https://github.com/apache/carbondata/pull/1538
This PR removes the Spark Dependency from Presto Integration Module for
using the CarbonVectorizedRecordreader, This PR consolidate
CarbonVectorizedRecordReader into one,to make it shared for all integration
modules
In the earlier version of Presto Integration we were using ColumnarBatch of
Spark, which is not a good practice, here we provided our own implementation of
the ColumnVector and the VectorBatch to eliminate the Spark all together. This
generic ColumnVector can now be used for all the integration module wherever we
want to have a VectorizedReader to speed up the processing.
There are some core module classes changed to ensure that we are using Java
data types instead of Spark datatypes, Decimal being one of them.
This PR tries to limit the changes to Core module .
Newly Added Classes
1.CarbonColumnVectorImpl:This Class Implements the Interface
CarbonColumnVector and provides the methods to store the data in a Vector and
to retrieved the data from it as well
2.CarbonVectorBatch: This Class Creates A VectorizedRowBatch which is a set
of rows, organized with each column as a CarbonVector. It is the unit of query
execution, organized to minimize the cost per row and achieve high
cycles-per-instruction. The major fields are public by design to allow fast and
convenient access by the vectorized query execution code.
3.StructField:This class is used to pass the Schema Information to the
Carbon Columnar Batch
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