public void addPTFNodeToSpec(ASTNode node, PTFInvocationSpec spec) {
    // Must be deterministic order map - see HIVE-8707
    ptfNodeToSpec = ptfNodeToSpec == null ? new LinkedHashMap<ASTNode, PTFInvocationSpec>() : ptfNodeToSpec;
    ptfNodeToSpec.put(node, spec);
  }
Retrieve skewed column name for a table.
@param alias table alias
@return
ql/src/java/org/apache/hadoop/hive/ql/parse/QB.java