org.apache.hadoop.zebra.io

Interface TableScanner

All Superinterfaces:

AutoCloseable, Closeable

public interface TableScanner
extends Closeable

Scanner interface allows application to scan a range of rows of a table. It is the caller's responsibility to close() the scanner after finishing using it. Scanner allows one to fetch the key without fetching the value to allow underlying implementation to instantiating tuple objects (Row) lazily.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	advance() Advance cursor to the next Row.
boolean	atEnd() Test whether the cursor is at the end of the scan range.
void	getKey(org.apache.hadoop.io.BytesWritable key) Get the row key.
String	getProjection()
Schema	getSchema() Get the projection's schema
void	getValue(Tuple row) Get the row.
boolean	seekTo(org.apache.hadoop.io.BytesWritable key) Seek to the key that is greater or equal to the provided key, or we reach the end.
void	seekToEnd() Seek to the end of the scan range.

Methods inherited from interface java.io.Closeable

close

Method Detail

atEnd

boolean atEnd()
              throws IOException

Test whether the cursor is at the end of the scan range.

Returns:

Whether the cursor is at the end of the scan range.

Throws:

IOException

advance

boolean advance()
                throws IOException

Advance cursor to the next Row.

Returns:

true if the cursor is moved. It will return true when the scanner moves the cursor from the last row to the end position.

Throws:

IOException

getKey

void getKey(org.apache.hadoop.io.BytesWritable key)
            throws IOException

Get the row key.

Parameters:

key - The output parameter to hold the result.

Throws:

IOException

getValue

void getValue(Tuple row)
              throws IOException

Get the row.

Parameters:

row - The output parameter to hold the result. It must conform to the schema that the scanner is aware of.

Throws:

IOException

See Also:

getSchema()

seekTo

boolean seekTo(org.apache.hadoop.io.BytesWritable key)
               throws IOException

Seek to the key that is greater or equal to the provided key, or we reach the end. It is only applicable to sorted tables.

Parameters:

key - The input key.

Returns:

true if we find the exact match; false otherwise.

Throws:

IOException

seekToEnd

void seekToEnd()
               throws IOException

Seek to the end of the scan range.

Throws:

IOException

getProjection

String getProjection()

getSchema

Schema getSchema()

Get the projection's schema