org.apache.hadoop.hive.ql.ppd
Class ExprWalkerProcFactory

java.lang.Object
  org.apache.hadoop.hive.ql.ppd.ExprWalkerProcFactory

public final class ExprWalkerProcFactory
extends Object

Expression factory for predicate pushdown processing. Each processor determines whether the expression is a possible candidate for predicate pushdown optimization for the given operator

Nested Class Summary

static class	ExprWalkerProcFactory.ColumnExprProcessor ColumnExprProcessor.
static class	ExprWalkerProcFactory.DefaultExprProcessor For constants and null expressions.
static class	ExprWalkerProcFactory.FieldExprProcessor FieldExprProcessor.
static class	ExprWalkerProcFactory.GenericFuncExprProcessor If all children are candidates and refer only to one table alias then this expr is a candidate else it is not a candidate but its children could be final candidates.

Method Summary

static ExprWalkerInfo	extractPushdownPreds(OpWalkerInfo opContext, Operator<? extends OperatorDesc> op, ExprNodeDesc pred)
static ExprWalkerInfo	extractPushdownPreds(OpWalkerInfo opContext, Operator<? extends OperatorDesc> op, List<ExprNodeDesc> preds) Extracts pushdown predicates from the given list of predicate expression.
static NodeProcessor	getColumnProcessor()
static NodeProcessor	getDefaultExprProcessor()
static NodeProcessor	getGenericFuncProcessor()

Methods inherited from class java.lang.Object

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

Method Detail

getDefaultExprProcessor

public static NodeProcessor getDefaultExprProcessor()

getGenericFuncProcessor

public static NodeProcessor getGenericFuncProcessor()

getColumnProcessor

public static NodeProcessor getColumnProcessor()

extractPushdownPreds

public static ExprWalkerInfo extractPushdownPreds(OpWalkerInfo opContext,
                                                  Operator<? extends OperatorDesc> op,
                                                  ExprNodeDesc pred)
                                           throws SemanticException

Throws:

SemanticException

extractPushdownPreds

public static ExprWalkerInfo extractPushdownPreds(OpWalkerInfo opContext,
                                                  Operator<? extends OperatorDesc> op,
                                                  List<ExprNodeDesc> preds)
                                           throws SemanticException

Extracts pushdown predicates from the given list of predicate expression.

Parameters:

opContext - operator context used for resolving column references

op - operator of the predicates being processed

preds -

Returns:

The expression walker information

Throws:

SemanticException