* @param opProcCtx
* context
*/
public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx opProcCtx,
Object... nodeOutputs) throws SemanticException {
UnionOperator union = (UnionOperator) nd;
GenMRProcContext ctx = (GenMRProcContext) opProcCtx;
ParseContext parseCtx = ctx.getParseCtx();
UnionProcContext uCtx = parseCtx.getUCtx();
// Map-only subqueries can be optimized in future to not write to a file in
// future
Map<Operator<? extends OperatorDesc>, GenMapRedCtx> mapCurrCtx = ctx.getMapCurrCtx();
if (union.getConf().isAllInputsInSameReducer()) {
// All inputs of this UnionOperator are in the same Reducer.
// We do not need to break the operator tree.
mapCurrCtx.put((Operator<? extends OperatorDesc>) nd,
new GenMapRedCtx(ctx.getCurrTask(),ctx.getCurrAliasId()));
return null;
}
UnionParseContext uPrsCtx = uCtx.getUnionParseContext(union);
ctx.setCurrUnionOp(union);
// The plan needs to be broken only if one of the sub-queries involve a
// map-reduce job
if (uPrsCtx.allMapOnlySubQ()) {
return processMapOnlyUnion(union, stack, ctx, uCtx);
}
assert uPrsCtx != null;
Task<? extends Serializable> currTask = ctx.getCurrTask();
int pos = UnionProcFactory.getPositionParent(union, stack);
Task<? extends Serializable> uTask = null;
MapredWork uPlan = null;
// union is encountered for the first time
GenMRUnionCtx uCtxTask = ctx.getUnionTask(union);
if (uCtxTask == null) {
uPlan = GenMapRedUtils.getMapRedWork(parseCtx);
uTask = TaskFactory.get(uPlan, parseCtx.getConf());
uCtxTask = new GenMRUnionCtx(uTask);
ctx.setUnionTask(union, uCtxTask);
}
else {
uTask = uCtxTask.getUTask();
}
// Copy into the current union task plan if
if (uPrsCtx.getMapOnlySubq(pos) && uPrsCtx.getRootTask(pos)) {
processSubQueryUnionMerge(ctx, uCtxTask, union, stack);
if (ctx.getRootTasks().contains(currTask)) {
ctx.getRootTasks().remove(currTask);
}
}
// If it a map-reduce job, create a temporary file
else {
// is the current task a root task
if (shouldBeRootTask(currTask)
&& !ctx.getRootTasks().contains(currTask)
&& (currTask.getParentTasks() == null
|| currTask.getParentTasks().isEmpty())) {
ctx.getRootTasks().add(currTask);
}
processSubQueryUnionCreateIntermediate(union.getParentOperators().get(pos), union, uTask,
ctx, uCtxTask);
// the currAliasId and CurrTopOp is not valid any more
ctx.setCurrAliasId(null);
ctx.setCurrTopOp(null);
ctx.getOpTaskMap().put(null, uTask);