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java.lang.Objectorg.apache.hadoop.hive.ql.optimizer.MapJoinProcessor
public class MapJoinProcessor
Implementation of one of the rule-based map join optimization. User passes hints to specify map-joins and during this optimization, all user specified map joins are converted to MapJoins - the reduce sink operator above the join are converted to map sink operators. In future, once statistics are implemented, this transformation can also be done based on costs.
Nested Class Summary | |
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static class |
MapJoinProcessor.CurrentMapJoin
CurrentMapJoin. |
static class |
MapJoinProcessor.Default
Default. |
static class |
MapJoinProcessor.MapJoinDefault
MapJoinDefault. |
static class |
MapJoinProcessor.MapJoinFS
MapJoinFS. |
static class |
MapJoinProcessor.MapJoinWalkerCtx
MapJoinWalkerCtx. |
Constructor Summary | |
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MapJoinProcessor()
empty constructor. |
Method Summary | |
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static void |
checkMapJoin(int mapJoinPos,
JoinCondDesc[] condns)
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static MapJoinOperator |
convertMapJoin(LinkedHashMap<Operator<? extends Serializable>,OpParseContext> opParseCtxMap,
JoinOperator op,
QBJoinTree joinTree,
int mapJoinPos,
boolean noCheckOuterJoin)
convert a regular join to a a map-side join. |
MapJoinOperator |
generateMapJoinOperator(ParseContext pctx,
JoinOperator op,
QBJoinTree joinTree,
int mapJoinPos)
|
static String |
genMapJoinOpAndLocalWork(MapredWork newWork,
JoinOperator op,
int mapJoinPos)
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static NodeProcessor |
getCurrentMapJoin()
|
static NodeProcessor |
getDefault()
|
static NodeProcessor |
getMapJoinDefault()
|
static NodeProcessor |
getMapJoinFS()
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static HashSet<Integer> |
getSmallTableOnlySet(JoinCondDesc[] condns)
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ParseContext |
transform(ParseContext pactx)
Transform the query tree. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public MapJoinProcessor()
Method Detail |
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public static String genMapJoinOpAndLocalWork(MapredWork newWork, JoinOperator op, int mapJoinPos) throws SemanticException
SemanticException
public static MapJoinOperator convertMapJoin(LinkedHashMap<Operator<? extends Serializable>,OpParseContext> opParseCtxMap, JoinOperator op, QBJoinTree joinTree, int mapJoinPos, boolean noCheckOuterJoin) throws SemanticException
op
- join operatorqbJoin
- qb join treemapJoinPos
- position of the source to be read as part of map-reduce framework. All other sources
are cached in memory
SemanticException
public MapJoinOperator generateMapJoinOperator(ParseContext pctx, JoinOperator op, QBJoinTree joinTree, int mapJoinPos) throws SemanticException
SemanticException
public static HashSet<Integer> getSmallTableOnlySet(JoinCondDesc[] condns)
public static void checkMapJoin(int mapJoinPos, JoinCondDesc[] condns) throws SemanticException
SemanticException
public ParseContext transform(ParseContext pactx) throws SemanticException
transform
in interface Transform
pactx
- current parse context
SemanticException
public static NodeProcessor getMapJoinFS()
public static NodeProcessor getMapJoinDefault()
public static NodeProcessor getDefault()
public static NodeProcessor getCurrentMapJoin()
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