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

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

All Implemented Interfaces:

Transform

public class PartitionPruner
extends Object
implements Transform

The transformation step that does partition pruning.

Field Summary

static String	CLASS_NAME
static org.apache.commons.logging.Log	LOG

Constructor Summary

PartitionPruner()

Method Summary

static boolean	hasColumnExpr(ExprNodeDesc desc) Whether the expression contains a column node or not.
static boolean	onlyContainsPartnCols(Table tab, ExprNodeDesc expr) Find out whether the condition only contains partitioned columns.
static PrunedPartitionList	prune(TableScanOperator ts, ParseContext parseCtx, String alias) Get the partition list for the TS operator that satisfies the partition pruner condition.
static boolean	prunePartitionNames(List<String> columnNames, ExprNodeGenericFuncDesc prunerExpr, String defaultPartitionName, List<String> partNames) Prunes partition names to see if they match the prune expression.
ParseContext	transform(ParseContext pctx) All transformation steps implement this interface.

Methods inherited from class java.lang.Object

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

Field Detail

CLASS_NAME

public static final String CLASS_NAME

LOG

public static final org.apache.commons.logging.Log LOG

Constructor Detail

PartitionPruner

public PartitionPruner()

Method Detail

transform

public ParseContext transform(ParseContext pctx)
                       throws SemanticException

Description copied from interface: Transform

All transformation steps implement this interface.

Specified by:

transform in interface Transform

Parameters:

pctx - input parse context

Returns:

ParseContext

Throws:

SemanticException

onlyContainsPartnCols

public static boolean onlyContainsPartnCols(Table tab,
                                            ExprNodeDesc expr)

Find out whether the condition only contains partitioned columns. Note that if the table is not partitioned, the function always returns true. condition.

Parameters:

tab - the table object

expr - the pruner expression for the table

prune

public static PrunedPartitionList prune(TableScanOperator ts,
                                        ParseContext parseCtx,
                                        String alias)
                                 throws HiveException

Get the partition list for the TS operator that satisfies the partition pruner condition.

Throws:

HiveException

prunePartitionNames

public static boolean prunePartitionNames(List<String> columnNames,
                                          ExprNodeGenericFuncDesc prunerExpr,
                                          String defaultPartitionName,
                                          List<String> partNames)
                                   throws HiveException,
                                          MetaException

Prunes partition names to see if they match the prune expression.

Parameters:

columnNames - name of partition columns

prunerExpr - The expression to match.

defaultPartitionName - name of default partition

partNames - Partition names to filter. The list is modified in place.

Returns:

Whether the list has any partitions for which the expression may or may not match.

Throws:

HiveException

MetaException

hasColumnExpr

public static boolean hasColumnExpr(ExprNodeDesc desc)

Whether the expression contains a column node or not.