Package org.apache.parquet.column.values.deltastrings

Class DeltaByteArrayReader

java.lang.Object

org.apache.parquet.column.values.ValuesReader

org.apache.parquet.column.values.deltastrings.DeltaByteArrayReader

All Implemented Interfaces:

RequiresPreviousReader

public class DeltaByteArrayReader
extends ValuesReader
implements RequiresPreviousReader

Reads binary data written by DeltaByteArrayWriter

Constructor Summary

Constructors

Constructor	Description
DeltaByteArrayReader()

Method Summary

Modifier and Type	Method	Description
void	initFromPage(int valueCount, org.apache.parquet.bytes.ByteBufferInputStream stream)	Called to initialize the column reader from a part of a page.
Binary	readBytes()
void	setPreviousReader(ValuesReader reader)	There was a bug (PARQUET-246) in which DeltaByteArrayWriter's reset() method did not clear the previous value state that it tracks internally.
void	skip()	Skips the next value in the page

Methods inherited from class org.apache.parquet.column.values.ValuesReader

getNextOffset, initFromPage, initFromPage, readBoolean, readDouble, readFloat, readInteger, readLong, readValueDictionaryId, skip, updateNextOffset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DeltaByteArrayReader

public DeltaByteArrayReader()

Method Detail

initFromPage

public void initFromPage(int valueCount,
                         org.apache.parquet.bytes.ByteBufferInputStream stream)
                  throws IOException

Description copied from class: ValuesReader

Called to initialize the column reader from a part of a page. Implementations must consume all bytes from the input stream, leaving the stream ready to read the next section of data. The underlying implementation knows how much data to read, so a length is not provided. Each page may contain several sections:

• repetition levels column
• definition levels column
• data column

Overrides:

initFromPage in class ValuesReader

Parameters:

valueCount - count of values in this page

stream - an input stream containing the page data at the correct offset

Throws:

IOException - if there is an exception while reading from the input stream

skip

public void skip()

Description copied from class: ValuesReader

Skips the next value in the page

Specified by:

skip in class ValuesReader

readBytes

public Binary readBytes()

Overrides:

readBytes in class ValuesReader

Returns:

the next Binary from the page

setPreviousReader

public void setPreviousReader(ValuesReader reader)

There was a bug (PARQUET-246) in which DeltaByteArrayWriter's reset() method did not clear the previous value state that it tracks internally. This resulted in the first value of all pages (except for the first page) to be a delta from the last value of the previous page. In order to read corrupted files written with this bug, when reading a new page we need to recover the previous page's last value to use it (if needed) to read the first value.

Specified by:

setPreviousReader in interface RequiresPreviousReader