Package org.apache.sysds.runtime.io

# Class ReaderDeltaParallel

java.lang.Object
org.apache.sysds.runtime.io.MatrixReader
org.apache.sysds.runtime.io.ReaderDelta
org.apache.sysds.runtime.io.ReaderDeltaParallel

public class ReaderDeltaParallel extends ReaderDelta
Parallel native Delta Lake matrix reader. Delta tables are stored as one or more parquet data files; this reader decodes those files concurrently (one task per data file) and then concatenates the per-file row-major buffers into the dense output in the original file order.

The expensive part of a Delta read is the parquet decode, which the kernel performs per data file; parallelizing across files is therefore the natural way to bridge the gap to the (near-raw) binary reader. A table backed by a single data file (the default for tables <= the parquet target file size) cannot be split this way, so the reader transparently falls back to the sequential `ReaderDelta` path in that case.

## Constructor Summary

Constructors
Constructor
Description
`ReaderDeltaParallel()`

## Method Summary

Modifier and Type
Method
Description
`MatrixBlock`
`readMatrixFromHDFS(String fname, long rlen, long clen, int blen, long estnnz)`

### Methods inherited from class org.apache.sysds.runtime.io.ReaderDelta

`readMatrixFromInputStream`

### Methods inherited from class org.apache.sysds.runtime.io.MatrixReader

`checkValidInputFile`

### Methods inherited from class java.lang.Object

`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

## Constructor Details

### ReaderDeltaParallel

public ReaderDeltaParallel()

## Method Details

### readMatrixFromHDFS

public MatrixBlock readMatrixFromHDFS(String fname, long rlen, long clen, int blen, long estnnz) throws IOException, DMLRuntimeException

Overrides:
  `readMatrixFromHDFS` in class `ReaderDelta`
Throws:
  `IOException`
  `DMLRuntimeException`