uk.ac.starlink.table.storage

Class SidewaysRowStore

java.lang.Object

uk.ac.starlink.table.storage.SidewaysRowStore

All Implemented Interfaces:

RowStore, TableSink

public class SidewaysRowStore
extends Object
implements RowStore

RowStore implementation which stores data cell data in a column-oriented fashion, so that members of the same column, rather than of the same row, are stored contiguously on disk.

Since:

21 Jun 2006

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
SidewaysRowStore() Constructs a new row store with an automatically chosen (and guaranteed unique) base pathname for scrach files.
SidewaysRowStore(File file) Constructs a new row store with a given base path name to use for temporary files.

Method Summary

Modifier and Type	Method and Description
void	acceptMetadata(StarTable meta) Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted.
void	acceptRow(Object[] row) Takes delivery of one row of data.
void	endRows() Signals that there are no more rows to be transmitted.
StarTable	getStarTable() Obtains a StarTable which contains the data and metadata that have been written into this sink.

Methods inherited from class java.lang.Object

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

Constructor Detail

SidewaysRowStore

public SidewaysRowStore(File file)
                 throws IOException

Constructs a new row store with a given base path name to use for temporary files.

Parameters:

file - base scratch file name

Throws:

IOException

SidewaysRowStore

public SidewaysRowStore()
                 throws IOException

Constructs a new row store with an automatically chosen (and guaranteed unique) base pathname for scrach files.

Throws:

IOException

Method Detail

acceptMetadata

public void acceptMetadata(StarTable meta)
                    throws TableFormatException

Description copied from interface: TableSink

Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted. If the number of rows that will be transmitted via subsequent calls to acceptRow is known, this value should be made available as the row count of meta (StarTable.getRowCount()); if it is not known, the row count should be -1. However, this object should not attempt to read any of meta's cell data.

The data to be transmitted in subsequent calls of acceptRow must match the metadata transmitted in this call in the same way that rows of a StarTable must match its own metadata (number and content clases of columns etc). If this sink cannot dispose of a table corresponding to meta then it may throw a TableFormatException - this may be the case if for instance meta has columns with types that this sink can't deal with.

Specified by:

acceptMetadata in interface TableSink

Parameters:

meta - table metadata object

Throws:

TableFormatException - if this sink cannot accept table rows matching the given metadata

acceptRow

public void acceptRow(Object[] row)
               throws IOException

Description copied from interface: TableSink

Takes delivery of one row of data. row is an array of objects comprising the contents of one row of the table being transmitted. The number and classes of the elements of row are described by the metadata object previously accepted.

Specified by:

acceptRow in interface TableSink

Parameters:

row - table data row

Throws:

IOException

endRows

public void endRows()
             throws IOException

Description copied from interface: TableSink

Signals that there are no more rows to be transmitted.

Specified by:

endRows in interface TableSink

Throws:

IOException

getStarTable

public StarTable getStarTable()

Description copied from interface: RowStore

Obtains a StarTable which contains the data and metadata that have been written into this sink. In general it is only legal to call this method following a call to TableSink.endRows(); failing to observe this sequence may earn you an IllegalStateException

Specified by:

getStarTable in interface RowStore

Returns:

a random-access StarTable containing the written rows