in ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/GenMRSkewJoinProcessor.java [110:365]
public static void processSkewJoin(JoinOperator joinOp,
Task<?> currTask, ParseContext parseCtx)
throws SemanticException {
// We are trying to adding map joins to handle skew keys, and map join right
// now does not work with outer joins
if (!GenMRSkewJoinProcessor.skewJoinEnabled(parseCtx.getConf(), joinOp)) {
return;
}
List<Task<?>> children = currTask.getChildTasks();
Path baseTmpDir = parseCtx.getContext().getMRTmpPath();
JoinDesc joinDescriptor = joinOp.getConf();
Map<Byte, List<ExprNodeDesc>> joinValues = joinDescriptor.getExprs();
int numAliases = joinValues.size();
Map<Byte, Path> bigKeysDirMap = new HashMap<Byte, Path>();
Map<Byte, Map<Byte, Path>> smallKeysDirMap = new HashMap<Byte, Map<Byte, Path>>();
Map<Byte, Path> skewJoinJobResultsDir = new HashMap<Byte, Path>();
Byte[] tags = joinDescriptor.getTagOrder();
for (int i = 0; i < numAliases; i++) {
Byte alias = tags[i];
bigKeysDirMap.put(alias, getBigKeysDir(baseTmpDir, alias));
Map<Byte, Path> smallKeysMap = new HashMap<Byte, Path>();
smallKeysDirMap.put(alias, smallKeysMap);
for (Byte src2 : tags) {
if (!src2.equals(alias)) {
smallKeysMap.put(src2, getSmallKeysDir(baseTmpDir, alias, src2));
}
}
skewJoinJobResultsDir.put(alias, getBigKeysSkewJoinResultDir(baseTmpDir,
alias));
}
joinDescriptor.setHandleSkewJoin(true);
joinDescriptor.setBigKeysDirMap(bigKeysDirMap);
joinDescriptor.setSmallKeysDirMap(smallKeysDirMap);
joinDescriptor.setSkewKeyDefinition(HiveConf.getIntVar(parseCtx.getConf(),
HiveConf.ConfVars.HIVE_SKEWJOIN_KEY));
HashMap<Path, Task<?>> bigKeysDirToTaskMap =
new HashMap<Path, Task<?>>();
List<Serializable> listWorks = new ArrayList<Serializable>();
List<Task<?>> listTasks = new ArrayList<Task<?>>();
MapredWork currPlan = (MapredWork) currTask.getWork();
TableDesc keyTblDesc = (TableDesc) currPlan.getReduceWork().getKeyDesc().clone();
List<String> joinKeys = Utilities
.getColumnNames(keyTblDesc.getProperties());
List<String> joinKeyTypes = Utilities.getColumnTypes(keyTblDesc
.getProperties());
Map<Byte, TableDesc> tableDescList = new HashMap<Byte, TableDesc>();
Map<Byte, RowSchema> rowSchemaList = new HashMap<Byte, RowSchema>();
Map<Byte, List<ExprNodeDesc>> newJoinValues = new HashMap<Byte, List<ExprNodeDesc>>();
Map<Byte, List<ExprNodeDesc>> newJoinKeys = new HashMap<Byte, List<ExprNodeDesc>>();
// used for create mapJoinDesc, should be in order
List<TableDesc> newJoinValueTblDesc = new ArrayList<TableDesc>();
for (Byte tag : tags) {
newJoinValueTblDesc.add(null);
}
for (int i = 0; i < numAliases; i++) {
Byte alias = tags[i];
List<ExprNodeDesc> valueCols = joinValues.get(alias);
String colNames = "";
String colTypes = "";
int columnSize = valueCols.size();
List<ExprNodeDesc> newValueExpr = new ArrayList<ExprNodeDesc>();
List<ExprNodeDesc> newKeyExpr = new ArrayList<ExprNodeDesc>();
ArrayList<ColumnInfo> columnInfos = new ArrayList<ColumnInfo>();
boolean first = true;
for (int k = 0; k < columnSize; k++) {
TypeInfo type = valueCols.get(k).getTypeInfo();
String newColName = i + "_VALUE_" + k; // any name, it does not matter.
ColumnInfo columnInfo = new ColumnInfo(newColName, type, alias.toString(), false);
columnInfos.add(columnInfo);
newValueExpr.add(new ExprNodeColumnDesc(columnInfo));
if (!first) {
colNames = colNames + ",";
colTypes = colTypes + ",";
}
first = false;
colNames = colNames + newColName;
colTypes = colTypes + valueCols.get(k).getTypeString();
}
// we are putting join keys at last part of the spilled table
for (int k = 0; k < joinKeys.size(); k++) {
if (!first) {
colNames = colNames + ",";
colTypes = colTypes + ",";
}
first = false;
colNames = colNames + joinKeys.get(k);
colTypes = colTypes + joinKeyTypes.get(k);
ColumnInfo columnInfo = new ColumnInfo(joinKeys.get(k), TypeInfoFactory
.getPrimitiveTypeInfo(joinKeyTypes.get(k)), alias.toString(), false);
columnInfos.add(columnInfo);
newKeyExpr.add(new ExprNodeColumnDesc(columnInfo));
}
newJoinValues.put(alias, newValueExpr);
newJoinKeys.put(alias, newKeyExpr);
tableDescList.put(alias, Utilities.getTableDesc(colNames, colTypes));
rowSchemaList.put(alias, new RowSchema(columnInfos));
// construct value table Desc
String valueColNames = "";
String valueColTypes = "";
first = true;
for (int k = 0; k < columnSize; k++) {
String newColName = i + "_VALUE_" + k; // any name, it does not matter.
if (!first) {
valueColNames = valueColNames + ",";
valueColTypes = valueColTypes + ",";
}
valueColNames = valueColNames + newColName;
valueColTypes = valueColTypes + valueCols.get(k).getTypeString();
first = false;
}
newJoinValueTblDesc.set(Byte.valueOf((byte) i), Utilities.getTableDesc(
valueColNames, valueColTypes));
}
joinDescriptor.setSkewKeysValuesTables(tableDescList);
joinDescriptor.setKeyTableDesc(keyTblDesc);
for (int i = 0; i < numAliases - 1; i++) {
Byte src = tags[i];
MapWork newPlan = PlanUtils.getMapRedWork().getMapWork();
// This code has been only added for testing
boolean mapperCannotSpanPartns =
parseCtx.getConf().getBoolVar(
HiveConf.ConfVars.HIVE_MAPPER_CANNOT_SPAN_MULTIPLE_PARTITIONS);
newPlan.setMapperCannotSpanPartns(mapperCannotSpanPartns);
MapredWork clonePlan = SerializationUtilities.clonePlan(currPlan);
Operator<? extends OperatorDesc>[] parentOps = new TableScanOperator[tags.length];
for (int k = 0; k < tags.length; k++) {
Operator<? extends OperatorDesc> ts =
GenMapRedUtils.createTemporaryTableScanOperator(
joinOp.getCompilationOpContext(), rowSchemaList.get((byte)k));
((TableScanOperator)ts).setTableDescSkewJoin(tableDescList.get((byte)k));
parentOps[k] = ts;
}
Operator<? extends OperatorDesc> tblScan_op = parentOps[i];
ArrayList<String> aliases = new ArrayList<String>();
String alias = src.toString().intern();
aliases.add(alias);
Path bigKeyDirPath = bigKeysDirMap.get(src);
newPlan.addPathToAlias(bigKeyDirPath, aliases);
newPlan.getAliasToWork().put(alias, tblScan_op);
PartitionDesc part = new PartitionDesc(tableDescList.get(src), null);
newPlan.addPathToPartitionInfo(bigKeyDirPath, part);
newPlan.getAliasToPartnInfo().put(alias, part);
Operator<? extends OperatorDesc> reducer = clonePlan.getReduceWork().getReducer();
assert reducer instanceof JoinOperator;
JoinOperator cloneJoinOp = (JoinOperator) reducer;
String dumpFilePrefix = "mapfile"+PlanUtils.getCountForMapJoinDumpFilePrefix();
MapJoinDesc mapJoinDescriptor = new MapJoinDesc(newJoinKeys, keyTblDesc,
newJoinValues, newJoinValueTblDesc, newJoinValueTblDesc,joinDescriptor
.getOutputColumnNames(), i, joinDescriptor.getConds(),
joinDescriptor.getFilters(), joinDescriptor.getNoOuterJoin(), dumpFilePrefix,
joinDescriptor.getMemoryMonitorInfo(), joinDescriptor.getInMemoryDataSize());
mapJoinDescriptor.setTagOrder(tags);
mapJoinDescriptor.setHandleSkewJoin(false);
mapJoinDescriptor.setNullSafes(joinDescriptor.getNullSafes());
mapJoinDescriptor.setColumnExprMap(joinDescriptor.getColumnExprMap());
MapredLocalWork localPlan = new MapredLocalWork(
new LinkedHashMap<String, Operator<? extends OperatorDesc>>(),
new LinkedHashMap<String, FetchWork>());
Map<Byte, Path> smallTblDirs = smallKeysDirMap.get(src);
for (int j = 0; j < numAliases; j++) {
if (j == i) {
continue;
}
Byte small_alias = tags[j];
Operator<? extends OperatorDesc> tblScan_op2 = parentOps[j];
localPlan.getAliasToWork().put(small_alias.toString(), tblScan_op2);
Path tblDir = smallTblDirs.get(small_alias);
localPlan.getAliasToFetchWork().put(small_alias.toString(),
new FetchWork(tblDir, tableDescList.get(small_alias)));
}
newPlan.setMapRedLocalWork(localPlan);
// construct a map join and set it as the child operator of tblScan_op
MapJoinOperator mapJoinOp = (MapJoinOperator) OperatorFactory.getAndMakeChild(
joinOp.getCompilationOpContext(), mapJoinDescriptor, (RowSchema) null, parentOps);
// change the children of the original join operator to point to the map
// join operator
List<Operator<? extends OperatorDesc>> childOps = cloneJoinOp
.getChildOperators();
for (Operator<? extends OperatorDesc> childOp : childOps) {
childOp.replaceParent(cloneJoinOp, mapJoinOp);
}
mapJoinOp.setChildOperators(childOps);
HiveConf jc = new HiveConf(parseCtx.getConf(),
GenMRSkewJoinProcessor.class);
newPlan.setNumMapTasks(HiveConf
.getIntVar(jc, HiveConf.ConfVars.HIVE_SKEWJOIN_MAPJOIN_NUM_MAP_TASK));
newPlan
.setMinSplitSize(HiveConf.getLongVar(jc, HiveConf.ConfVars.HIVE_SKEWJOIN_MAPJOIN_MIN_SPLIT));
newPlan.setInputformat(HiveInputFormat.class.getName());
MapredWork w = new MapredWork();
w.setMapWork(newPlan);
Task<?> skewJoinMapJoinTask = TaskFactory.get(w);
skewJoinMapJoinTask.setFetchSource(currTask.isFetchSource());
bigKeysDirToTaskMap.put(bigKeyDirPath, skewJoinMapJoinTask);
listWorks.add(skewJoinMapJoinTask.getWork());
listTasks.add(skewJoinMapJoinTask);
}
if (children != null) {
for (Task<?> tsk : listTasks) {
for (Task<?> oldChild : children) {
tsk.addDependentTask(oldChild);
}
}
currTask.setChildTasks(new ArrayList<Task<?>>());
for (Task<?> oldChild : children) {
oldChild.getParentTasks().remove(currTask);
}
listTasks.addAll(children);
}
ConditionalResolverSkewJoinCtx context =
new ConditionalResolverSkewJoinCtx(bigKeysDirToTaskMap, children);
ConditionalWork cndWork = new ConditionalWork(listWorks);
ConditionalTask cndTsk = (ConditionalTask) TaskFactory.get(cndWork);
cndTsk.setListTasks(listTasks);
cndTsk.setResolver(new ConditionalResolverSkewJoin());
cndTsk.setResolverCtx(context);
currTask.setChildTasks(new ArrayList<Task<?>>());
currTask.addDependentTask(cndTsk);
return;
}