org.apache.lens.server.api.query
Interface QueryOutputFormatter

All Known Subinterfaces:

InMemoryOutputFormatter, PersistedOutputFormatter

All Known Implementing Classes:

AbstractFileFormatter, AbstractOutputFormatter, FilePersistentFormatter, FileSerdeFormatter, HadoopFileFormatter, WrappedFileFormatter, ZipFileFormatter

public interface QueryOutputFormatter

The interface for query result formatting

This is an abstract interface, user should implement InMemoryOutputFormatter or PersistedOutputFormatter for formatting the result.

Method Summary

void	close() Close the formatter.
void	commit() Commit the formatting.
String	getFinalOutputPath() Get final location where formatted output is available
LensResultSetMetadata	getMetadata() Get resultset metadata
int	getNumRows() Get total number of rows in result.
void	init(QueryContext ctx, LensResultSetMetadata metadata) Initialize the formatter.
void	writeFooter() Write the footer.
void	writeHeader() Write the header.

Method Detail

init

void init(QueryContext ctx,
          LensResultSetMetadata metadata)
          throws IOException

Initialize the formatter.

Parameters:

ctx - The QueryContext object

metadata - LensResultSetMetadata object

Throws:

IOException - Signals that an I/O exception has occurred.

writeHeader

void writeHeader()
                 throws IOException

Write the header.

Throws:

IOException - Signals that an I/O exception has occurred.

writeFooter

void writeFooter()
                 throws IOException

Write the footer.

Throws:

IOException - Signals that an I/O exception has occurred.

commit

void commit()
            throws IOException

Commit the formatting.

This will make the result consumable by user, will be called after all the writes succeed.

Throws:

IOException - Signals that an I/O exception has occurred.

close

void close()
           throws IOException

Close the formatter. Cleanup any resources.

Throws:

IOException - Signals that an I/O exception has occurred.

getFinalOutputPath

String getFinalOutputPath()

Get final location where formatted output is available

Returns:

getNumRows

int getNumRows()

Get total number of rows in result.

Returns:

Total number of rows, return -1, if not known

getMetadata

LensResultSetMetadata getMetadata()

Get resultset metadata

Returns:

LensResultSetMetadata