Package org.apache.druid.frame.field
Class RowReader
- java.lang.Object
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- org.apache.druid.frame.field.RowReader
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public class RowReader extends Object
Class for reading rows in the same format as used byFrameType.ROW_BASED
. Stateless and immutable. Row format: - 4 bytes * rowLength: field *end* pointers (exclusive), relative to the start of the row, little-endian ints - N bytes * rowLength: fields written byFieldWriter
implementations.
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Constructor Summary
Constructors Constructor Description RowReader(List<FieldReader> fieldReaders)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
fieldCount()
FieldReader
fieldReader(int fieldNumber)
Object
readField(org.apache.datasketches.memory.Memory memory, long rowPosition, long rowLength, int fieldNumber)
Read a particular field value as an object.List<Object>
readRow(org.apache.datasketches.memory.Memory memory, long rowPosition, long rowLength)
Read an entire row as a list of objects.
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Constructor Detail
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RowReader
public RowReader(List<FieldReader> fieldReaders)
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Method Detail
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fieldReader
public FieldReader fieldReader(int fieldNumber)
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fieldCount
public int fieldCount()
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readField
public Object readField(org.apache.datasketches.memory.Memory memory, long rowPosition, long rowLength, int fieldNumber)
Read a particular field value as an object. For performance reasons, preferFrameReader.makeCursorFactory(org.apache.druid.frame.Frame)
for reading many rows out of a frame.
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readRow
public List<Object> readRow(org.apache.datasketches.memory.Memory memory, long rowPosition, long rowLength)
Read an entire row as a list of objects. For performance reasons, preferFrameReader.makeCursorFactory(org.apache.druid.frame.Frame)
for reading many rows out of a frame.
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