simpledb.multibuffer
Class ChunkScan

java.lang.Object
  simpledb.multibuffer.ChunkScan

All Implemented Interfaces:

Scan

public class ChunkScan
extends Object
implements Scan

The class for the chunk operator.

Author:

Edward Sciore

Constructor Summary

ChunkScan(TableInfo ti, int startbnum, int endbnum, Transaction tx)
Creates a chunk consisting of the specified pages.

Method Summary

void	beforeFirst() Positions the scan before its first record.
void	close() Closes the scan and its subscans, if any.
int	getInt(String fldname) Returns the value of the specified integer field in the current record.
String	getString(String fldname) Returns the value of the specified string field in the current record.
Constant	getVal(String fldname) Returns the value of the specified field in the current record.
boolean	hasField(String fldname) Returns true if the scan has the specified field.
boolean	next() Moves to the next record in the current block of the chunk.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChunkScan

public ChunkScan(TableInfo ti,
                 int startbnum,
                 int endbnum,
                 Transaction tx)

Creates a chunk consisting of the specified pages.

Parameters:

ti - the metadata for the chunked table

startbnum - the starting block number

endbnum - the ending block number

tx - the current transaction

Method Detail

beforeFirst

public void beforeFirst()

Description copied from interface: Scan

Positions the scan before its first record.

Specified by:

beforeFirst in interface Scan

See Also:

Scan.beforeFirst()

next

public boolean next()

Moves to the next record in the current block of the chunk. If there are no more records, then make the next block be current. If there are no more blocks in the chunk, return false.

Specified by:

next in interface Scan

Returns:

false if there is no next record

See Also:

Scan.next()

close

public void close()

Description copied from interface: Scan

Closes the scan and its subscans, if any.

Specified by:

close in interface Scan

See Also:

Scan.close()

getVal

public Constant getVal(String fldname)

Description copied from interface: Scan

Returns the value of the specified field in the current record. The value is expressed as a Constant.

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)

Description copied from interface: Scan

Returns the value of the specified integer field in the current record.

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)

Description copied from interface: Scan

Returns the value of the specified string field in the current record.

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)

Description copied from interface: Scan

Returns true if the scan has the specified field.

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)