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

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

public final class ExprProcFactory
extends Object

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.

Nested Class Summary

static class	ExprProcFactory.ColumnExprProcessor Processor for column expressions.
static class	ExprProcFactory.DefaultExprProcessor Processor for constants and null expressions.
static class	ExprProcFactory.FieldExprProcessor FieldExprProcessor.
static class	ExprProcFactory.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 ExprNodeDesc	genPruner(String tabAlias, ExprNodeDesc pred, boolean hasNonPartCols) Generates the partition pruner for the expression tree.
static NodeProcessor	getColumnProcessor()
static NodeProcessor	getDefaultExprProcessor()
static NodeProcessor	getFieldProcessor()
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()

getFieldProcessor

public static NodeProcessor getFieldProcessor()

getColumnProcessor

public static NodeProcessor getColumnProcessor()

genPruner

public static ExprNodeDesc genPruner(String tabAlias,
                                     ExprNodeDesc pred,
                                     boolean hasNonPartCols)
                              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:

hasNonPartCols returns true/false depending upon whether this pred has a non partition column

Throws:

SemanticException