org.vanilladb.core.query.algebra

Class TablePlan

java.lang.Object

org.vanilladb.core.query.algebra.TablePlan

All Implemented Interfaces:

Plan

public class TablePlan
extends Object
implements Plan

The Plan class corresponding to a table.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
long	blocksAccessed() Estimates the number of block accesses for the table, which is obtainable from the statistics manager.
Histogram	histogram() Returns the histogram that approximates the join distribution of the field values of query results.
Scan	open() Creates a table scan for this query.
long	recordsOutput() Returns an estimate of the number of records in the query's output table.
Schema	schema() Determines the schema of the table, which is obtainable from the catalog manager.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, 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 long 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()

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()

histogram

public Histogram histogram()

Returns the histogram that approximates the join distribution of the field values of query results.

Specified by:

histogram in interface Plan

Returns:

the histogram

See Also:

Plan.histogram()

recordsOutput

public long recordsOutput()

Description copied from interface: Plan

Returns an estimate of the number of records in the query's output table.

Specified by:

recordsOutput in interface Plan

Returns:

the estimated number of output records

toString

public String toString()

Overrides:

toString in class Object