simpledb.multibuffer
Class MultiBufferProductScan

java.lang.Object
  simpledb.multibuffer.MultiBufferProductScan

All Implemented Interfaces:

Scan

public class MultiBufferProductScan
extends Object
implements Scan

The Scan class for the muti-buffer version of the product operator.

Author:

Edward Sciore

Constructor Summary

MultiBufferProductScan(Scan lhsscan, TableInfo ti, Transaction tx)
Creates the scan class for the product of the LHS scan and a table.

Method Summary

void	beforeFirst() Positions the scan before the first record.
void	close() Closes the current scans.
int	getInt(String fldname) Returns the integer value of the specified field.
String	getString(String fldname) Returns the string value of the specified field.
Constant	getVal(String fldname) Returns the value of the specified field.
boolean	hasField(String fldname) Returns true if the specified field is in either of the underlying scans.
boolean	next() Moves to the next record in the current scan.

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiBufferProductScan

public MultiBufferProductScan(Scan lhsscan,
                              TableInfo ti,
                              Transaction tx)

Creates the scan class for the product of the LHS scan and a table.

Parameters:

lhsscan - the LHS scan

ti - the metadata for the RHS table

tx - the current transaction

Method Detail

beforeFirst

public void beforeFirst()

Positions the scan before the first record. That is, the LHS scan is positioned at its first record, and the RHS scan is positioned before the first record of the first chunk.

Specified by:

beforeFirst in interface Scan

See Also:

Scan.beforeFirst()

next

public boolean next()

Moves to the next record in the current scan. If there are no more records in the current chunk, then move to the next LHS record and the beginning of that chunk. If there are no more LHS records, then move to the next chunk and begin again.

Specified by:

next in interface Scan

Returns:

false if there is no next record

See Also:

Scan.next()

close

public void close()

Closes the current scans.

Specified by:

close in interface Scan

See Also:

Scan.close()

getVal

public Constant getVal(String fldname)

Returns the value of the specified field. The value is obtained from whichever scan contains the field.

Specified by:

getVal in interface Scan

Parameters:

fldname - the name of the field

Returns:

the value of that field, expressed as a Constant.

See Also:

Scan.getVal(java.lang.String)

getInt

public int getInt(String fldname)

Returns the integer value of the specified field. The value is obtained from whichever scan contains the field.

Specified by:

getInt in interface Scan

Parameters:

fldname - the name of the field

Returns:

the field's integer value in the current record

See Also:

Scan.getInt(java.lang.String)

getString

public String getString(String fldname)

Returns the string value of the specified field. The value is obtained from whichever scan contains the field.

Specified by:

getString in interface Scan

Parameters:

fldname - the name of the field

Returns:

the field's string value in the current record

See Also:

Scan.getString(java.lang.String)

hasField

public boolean hasField(String fldname)

Returns true if the specified field is in either of the underlying scans.

Specified by:

hasField in interface Scan

Parameters:

fldname - the name of the field

Returns:

true if the scan has that field

See Also:

Scan.hasField(java.lang.String)