ValuesReader (Apache Parquet Column 1.11.1 API)

java.lang.Object
- org.apache.parquet.column.values.ValuesReader

Direct Known Subclasses:

BinaryPlainValuesReader, BitPackingValuesReader, BooleanPlainValuesReader, ByteBitPackingValuesReader, DeltaBinaryPackingValuesReader, DeltaByteArrayReader, DeltaLengthByteArrayValuesReader, DictionaryValuesReader, FixedLenByteArrayPlainValuesReader, PlainValuesReader, RunLengthBitPackingHybridValuesReader, ZeroIntegerValuesReader
```
public abstract class ValuesReader
extends Object
```
Base class to implement an encoding for a given column type. A ValuesReader is provided with a page (byte-buffer) and is responsible for deserializing the primitive values stored in that page. Given that pages are homogeneous (store only a single type), typical subclasses will only override one of the read*() methods.

Constructor Summary

Constructors
Constructor and Description

ValuesReader()

Constructors
Constructor and Description
`ValuesReader()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`int`	`getNextOffset()` Deprecated. Will be removed in 2.0.0
`void`	`initFromPage(int valueCount, byte[] page, int offset)` Deprecated.
`void`	`initFromPage(int valueCount, ByteBufferInputStream in)` Called to initialize the column reader from a part of a page.
`void`	`initFromPage(int valueCount, ByteBuffer page, int offset)` Deprecated. Will be removed in 2.0.0
`boolean`	`readBoolean()`
`Binary`	`readBytes()`
`double`	`readDouble()`
`float`	`readFloat()`
`int`	`readInteger()`
`long`	`readLong()`
`int`	`readValueDictionaryId()` usable when the encoding is dictionary based
`abstract void`	`skip()` Skips the next value in the page
`void`	`skip(int n)` Skips the next n values in the page
`protected void`	`updateNextOffset(int bytesRead)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ValuesReader
```
public ValuesReader()
```
- Method Detail
  - initFromPage
```
@Deprecated
public void initFromPage(int valueCount,
                                     ByteBuffer page,
                                     int offset)
                              throws IOException
```
    Deprecated. Will be removed in 2.0.0
    Called to initialize the column reader from a part of a page. 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
    This function is called with 'offset' pointing to the beginning of one of these sections, and should return the offset to the section following it.
    Parameters:
    
    valueCount - count of values in this page
    
    page - the array to read from containing the page data (repetition levels, definition levels, data)
    
    offset - where to start reading from in the page
    
    Throws:
    
    IOException
  - initFromPage
```
@Deprecated
public void initFromPage(int valueCount,
                                     byte[] page,
                                     int offset)
                              throws IOException
```
    Deprecated.
    
    Same functionality as method of the same name that takes a ByteBuffer instead of a byte[]. This method is only provided for backward compatibility and will be removed in a future release. Please update any code using it as soon as possible.
    
    Throws:
    
    IOException
    
    See Also:
    
    initFromPage(int, ByteBuffer, int)
  - initFromPage
```
public void initFromPage(int valueCount,
                         ByteBufferInputStream in)
                  throws IOException
```
    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
    Parameters:
    
    valueCount - count of values in this page
    
    in - an input stream containing the page data at the correct offset
    
    Throws:
    
    IOException - if there is an exception while reading from the input stream
  - getNextOffset
```
@Deprecated
public int getNextOffset()
```
    Deprecated. Will be removed in 2.0.0
    
    Called to return offset of the next section
    
    Returns:
    
    offset of the next section
  - updateNextOffset
```
protected void updateNextOffset(int bytesRead)
```
  - readValueDictionaryId
```
public int readValueDictionaryId()
```
    usable when the encoding is dictionary based
    
    Returns:
    
    the id of the next value from the page
  - readBoolean
```
public boolean readBoolean()
```
    Returns:
    
    the next boolean from the page
  - readBytes
```
public Binary readBytes()
```
    Returns:
    
    the next Binary from the page
  - readFloat
```
public float readFloat()
```
    Returns:
    
    the next float from the page
  - readDouble
```
public double readDouble()
```
    Returns:
    
    the next double from the page
  - readInteger
```
public int readInteger()
```
    Returns:
    
    the next integer from the page
  - readLong
```
public long readLong()
```
    Returns:
    
    the next long from the page
  - skip
```
public abstract void skip()
```
    Skips the next value in the page
  - skip
```
public void skip(int n)
```
    Skips the next n values in the page
    
    Parameters:
    
    n - the number of values to be skipped

Class ValuesReader

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ValuesReader

Method Detail

initFromPage

initFromPage

initFromPage

getNextOffset

updateNextOffset

readValueDictionaryId

readBoolean

readBytes

readFloat

readDouble

readInteger

readLong

skip

skip