@Override
  public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx opProcCtx,
      Object... nodeOutputs) throws SemanticException {
    TableScanOperator op = (TableScanOperator) nd;
    GenMRProcContext ctx = (GenMRProcContext) opProcCtx;
    ctx.reset();

    ParseContext parseCtx = ctx.getParseCtx();
    Table table = op.getConf().getTableMetadata();
    Class<? extends InputFormat> inputFormat = table.getInputFormatClass();
    Map<Operator<? extends OperatorDesc>, GenMapRedCtx> mapCurrCtx = ctx.getMapCurrCtx();

    // create a dummy MapReduce task
    MapredWork currWork = GenMapRedUtils.getMapRedWork(parseCtx);
    MapRedTask currTask = (MapRedTask) TaskFactory.get(currWork);
    ctx.setCurrTask(currTask);
    ctx.setCurrTopOp(op);

    for (String alias : parseCtx.getTopOps().keySet()) {
      Operator<? extends OperatorDesc> currOp = parseCtx.getTopOps().get(alias);
      if (currOp == op) {
        String currAliasId = alias;
        ctx.setCurrAliasId(currAliasId);
        mapCurrCtx.put(op, new GenMapRedCtx(currTask, currAliasId));

        if (parseCtx.getQueryProperties().isAnalyzeCommand()) {
          boolean noScan = parseCtx.getQueryProperties().isNoScanAnalyzeCommand();
          if (BasicStatsNoJobTask.canUseBasicStats(table, inputFormat)) {
            // For ORC and Parquet, all the following statements are the same
            // ANALYZE TABLE T [PARTITION (...)] COMPUTE STATISTICS
            // ANALYZE TABLE T [PARTITION (...)] COMPUTE STATISTICS noscan;

            // There will not be any MR or Tez job above this task
            StatsWork statWork = new StatsWork(table, parseCtx.getConf());
            statWork.setFooterScan();

            // If partition is specified, get pruned partition list
            Set<Partition> confirmedParts = GenMapRedUtils.getConfirmedPartitionsForScan(op);
            if (confirmedParts.size() > 0) {
              List<String> partCols = GenMapRedUtils.getPartitionColumns(op);
              PrunedPartitionList partList = new PrunedPartitionList(table, confirmedParts, partCols, false);
              statWork.addInputPartitions(partList.getPartitions());
            }
            Task<StatsWork> snjTask = TaskFactory.get(statWork);
            ctx.setCurrTask(snjTask);
            ctx.setCurrTopOp(null);
            ctx.getRootTasks().clear();
            ctx.getRootTasks().add(snjTask);
          } else {
            // ANALYZE TABLE T [PARTITION (...)] COMPUTE STATISTICS;
            // The plan consists of a simple MapRedTask followed by a StatsTask.
            // The MR task is just a simple TableScanOperator

            BasicStatsWork statsWork = new BasicStatsWork(table.getTableSpec());
            statsWork.setIsExplicitAnalyze(true);

            statsWork.setNoScanAnalyzeCommand(noScan);
            StatsWork columnStatsWork = new StatsWork(table, statsWork, parseCtx.getConf());
            columnStatsWork.collectStatsFromAggregator(op.getConf());

            columnStatsWork.setSourceTask(currTask);
            Task<StatsWork> columnStatsTask = TaskFactory.get(columnStatsWork);
            currTask.addDependentTask(columnStatsTask);
            if (!ctx.getRootTasks().contains(currTask)) {
              ctx.getRootTasks().add(currTask);
            }

            // ANALYZE TABLE T [PARTITION (...)] COMPUTE STATISTICS noscan;
            // The plan consists of a StatsTask only.
            if (noScan) {
              columnStatsTask.setParentTasks(null);
              ctx.getRootTasks().remove(currTask);
              ctx.getRootTasks().add(columnStatsTask);
            }

            currWork.getMapWork().setGatheringStats(true);
            if (currWork.getReduceWork() != null) {
              currWork.getReduceWork().setGatheringStats(true);
            }

            // NOTE: here we should use the new partition predicate pushdown API to get a list of
            // pruned list,
            // and pass it to setTaskPlan as the last parameter
            Set<Partition> confirmedPartns = GenMapRedUtils
                .getConfirmedPartitionsForScan(op);
            if (confirmedPartns.size() > 0) {
              List<String> partCols = GenMapRedUtils.getPartitionColumns(op);
              PrunedPartitionList partList = new PrunedPartitionList(table, confirmedPartns, partCols, false);
              GenMapRedUtils.setTaskPlan(currAliasId, op, currTask, false, ctx, partList);
            } else { // non-partitioned table
              GenMapRedUtils.setTaskPlan(currAliasId, op, currTask, false, ctx);
            }
          }
        }

        return true;
      }
    }
    assert false;
    return null;
  }
Table Sink encountered.
@param nd
         the table sink operator encountered
@param opProcCtx
         context
ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMRTableScan1.java