* @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 Serializable>, GenMapRedCtx> mapCurrCtx = ctx.getMapCurrCtx();
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) {
uCtxTask = new GenMRUnionCtx();
uPlan = GenMapRedUtils.getMapRedWork(parseCtx);
uTask = TaskFactory.get(uPlan, parseCtx.getConf());
uCtxTask.setUTask(uTask);
ctx.setUnionTask(union, uCtxTask);
}
else {
uTask = uCtxTask.getUTask();
}
// Copy into the current union task plan if
if (uPrsCtx.getMapOnlySubq(pos)
&& !uPrsCtx.getMapJoinSubq(pos) && uPrsCtx.getRootTask(pos)) {
processSubQueryUnionMerge(ctx, uCtxTask, union, stack);
}
// If it a map-reduce job, create a temporary file
else {
// is the current task a root task
if (shouldBeRootTask(currTask, parseCtx)
&& (!ctx.getRootTasks().contains(currTask))) {
ctx.getRootTasks().add(currTask);
}
// If there is a mapjoin at position 'pos'
if (uPrsCtx.getMapJoinSubq(pos)) {
processSubQueryUnionMapJoin(ctx);
}
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);
}