simpledb.materialize
Class MaterializePlan

java.lang.Object
  simpledb.materialize.MaterializePlan

All Implemented Interfaces:

Plan

public class MaterializePlan
extends Object
implements Plan

The Plan class for the materialize operator.

Author:

Edward Sciore

Constructor Summary

MaterializePlan(Plan srcplan, Transaction tx)
Creates a materialize plan for the specified query.

Method Summary

int	blocksAccessed() Returns the estimated number of blocks in the materialized table.
int	distinctValues(String fldname) Returns the number of distinct field values, which is the same as in the underlying plan.
Scan	open() This method loops through the underlying query, copying its output records into a temporary table.
int	recordsOutput() Returns the number of records in the materialized table, which is the same as in the underlying plan.
Schema	schema() Returns the schema of the materialized table, which is the same as in the underlying plan.

Methods inherited from class java.lang.Object

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

Constructor Detail

MaterializePlan

public MaterializePlan(Plan srcplan,
                       Transaction tx)

Creates a materialize plan for the specified query.

Parameters:

srcplan - the plan of the underlying query

tx - the calling transaction

Method Detail

open

public Scan open()

This method loops through the underlying query, copying its output records into a temporary table. It then returns a table scan for that table.

Specified by:

open in interface Plan

Returns:

a scan

See Also:

Plan.open()

blocksAccessed

public int blocksAccessed()

Returns the estimated number of blocks in the materialized table. It does not include the one-time cost of materializing the records.

Specified by:

blocksAccessed in interface Plan

Returns:

the estimated number of block accesses

See Also:

Plan.blocksAccessed()

recordsOutput

public int recordsOutput()

Returns the number of records in the materialized table, which is the same as in the underlying plan.

Specified by:

recordsOutput in interface Plan

Returns:

the estimated number of output records

See Also:

Plan.recordsOutput()

distinctValues

public int distinctValues(String fldname)

Returns the number of distinct field values, which is the same as in the underlying plan.

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()

Returns the schema of the materialized table, which is the same as in the underlying plan.

Specified by:

schema in interface Plan

Returns:

the query's schema

See Also:

Plan.schema()