Class QueryOptimizer.ColumnPruning

java.lang.Object

com.loomcache.server.query.QueryOptimizer.ColumnPruning

All Implemented Interfaces:

QueryOptimizer.OptimizationRule

Enclosing class:

QueryOptimizer

public static final class QueryOptimizer.ColumnPruning
extends Object
implements QueryOptimizer.OptimizationRule

Column pruning optimization: only loads columns needed by SELECT, WHERE, and ORDER BY.

Constructor Summary

Constructors

Constructor	Description
ColumnPruning()

Method Summary

Modifier and Type	Method	Description
QueryPlan	apply(QueryPlan plan, @Nullable QueryOptimizer.TableStatistics stats, Map<String, MapIndex<?,?>> availableIndexes)	Applies this optimization rule to the given query plan.
String	name()	Gets the name of this optimization rule.

Methods inherited from class Object

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

Constructor Details

ColumnPruning

public ColumnPruning()

Method Details

name

public String name()

Description copied from interface: QueryOptimizer.OptimizationRule

Gets the name of this optimization rule.

Specified by:

name in interface QueryOptimizer.OptimizationRule

apply

public QueryPlan apply(QueryPlan plan,
 @Nullable QueryOptimizer.TableStatistics stats,
 Map<String, MapIndex<?,?>> availableIndexes)

Description copied from interface: QueryOptimizer.OptimizationRule

Applies this optimization rule to the given query plan.

Specified by:

apply in interface QueryOptimizer.OptimizationRule

Parameters:

plan - the original query plan

stats - table statistics (if available)

availableIndexes - available indexes for the table

Returns:

optimized query plan, or original if optimization cannot be applied