simpledb.query
Class TablePlan

java.lang.Object
  simpledb.query.TablePlan

All Implemented Interfaces:

Plan

public class TablePlan
extends Object
implements Plan

The Plan class corresponding to a table.

Author:

Edward Sciore

Constructor Summary

TablePlan(String tblname, Transaction tx)
Creates a leaf node in the query tree corresponding to the specified table.

Method Summary

int	blocksAccessed() Estimates the number of block accesses for the table, which is obtainable from the statistics manager.
int	distinctValues(String fldname) Estimates the number of distinct field values in the table, which is obtainable from the statistics manager.
Scan	open() Creates a table scan for this query.
int	recordsOutput() Estimates the number of records in the table, which is obtainable from the statistics manager.
Schema	schema() Determines the schema of the table, which is obtainable from the catalog manager.

Methods inherited from class java.lang.Object

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

Constructor Detail

TablePlan

public TablePlan(String tblname,
                 Transaction tx)

Creates a leaf node in the query tree corresponding to the specified table.

Parameters:

tblname - the name of the table

tx - the calling transaction

Method Detail

open

public Scan open()

Creates a table scan for this query.

Specified by:

open in interface Plan

Returns:

a scan

See Also:

Plan.open()

blocksAccessed

public int blocksAccessed()

Estimates the number of block accesses for the table, which is obtainable from the statistics manager.

Specified by:

blocksAccessed in interface Plan

Returns:

the estimated number of block accesses

See Also:

Plan.blocksAccessed()

recordsOutput

public int recordsOutput()

Estimates the number of records in the table, which is obtainable from the statistics manager.

Specified by:

recordsOutput in interface Plan

Returns:

the estimated number of output records

See Also:

Plan.recordsOutput()

distinctValues

public int distinctValues(String fldname)

Estimates the number of distinct field values in the table, which is obtainable from the statistics manager.

Specified by:

distinctValues in interface Plan

Parameters:

fldname - the name of a field

Returns:

the estimated number of distinct field values in the output

See Also:

Plan.distinctValues(java.lang.String)

schema

public Schema schema()

Determines the schema of the table, which is obtainable from the catalog manager.

Specified by:

schema in interface Plan

Returns:

the query's schema

See Also:

Plan.schema()