org.apache.hadoop.hive.ql.optimizer.ppr
Class ExprProcFactory

java.lang.Object
  org.apache.hadoop.hive.ql.optimizer.PrunerExpressionOperatorFactory
      org.apache.hadoop.hive.ql.optimizer.ppr.ExprProcFactory

public final class ExprProcFactory
extends PrunerExpressionOperatorFactory

Expression processor factory for partition pruning. Each processor tries to convert the expression subtree into a partition pruning expression. This expression is then used to figure out whether a particular partition should be scanned or not. * Refactor: Move main logic to PrunerExpressionOperatorFactory. ExprProcFactory extends it to reuse logic. Any other pruner can reuse it by creating a class extending from PrunerExpressionOperatorFactory. Only specific logic is in genPruner(..) which is in its own class like ExprProcFactory.

Nested Class Summary

static class

ExprProcFactory.PPRColumnExprProcessor Processor for ppr column expressions.

Nested classes/interfaces inherited from class org.apache.hadoop.hive.ql.optimizer.PrunerExpressionOperatorFactory

PrunerExpressionOperatorFactory.ColumnExprProcessor, PrunerExpressionOperatorFactory.DefaultExprProcessor, PrunerExpressionOperatorFactory.FieldExprProcessor, PrunerExpressionOperatorFactory.GenericFuncExprProcessor

Method Summary

static ExprNodeDesc	genPruner(String tabAlias, ExprNodeDesc pred) Generates the partition pruner for the expression tree.
static NodeProcessor	getColumnProcessor() Instantiate column processor.

Methods inherited from class org.apache.hadoop.hive.ql.optimizer.PrunerExpressionOperatorFactory

getDefaultExprProcessor, getFieldProcessor, getGenericFuncProcessor

Methods inherited from class java.lang.Object

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

Method Detail

getColumnProcessor

public static NodeProcessor getColumnProcessor()

Instantiate column processor.

Returns:

genPruner

public static ExprNodeDesc genPruner(String tabAlias,
                                     ExprNodeDesc pred)
                              throws SemanticException

Generates the partition pruner for the expression tree.

Parameters:

tabAlias - The table alias of the partition table that is being considered for pruning

pred - The predicate from which the partition pruner needs to be generated

Returns:

The pruner expression.

Throws:

SemanticException