private boolean applies(SchemaContext sc, DMLStatement stmt) throws PEException {
   if (stmt instanceof UpdateStatement) {
     UpdateStatement us = (UpdateStatement) stmt;
     for (Iterator<ExpressionNode> iter = us.getUpdateExpressionsEdge().iterator();
         iter.hasNext(); ) {
       FunctionCall fc = (FunctionCall) iter.next();
       ColumnInstance lhs = (ColumnInstance) fc.getParametersEdge().get(0);
       if (lhs.getPEColumn().isPartOfContainerDistributionVector())
         throw new SchemaException(
             new ErrorInfo(
                 AvailableErrors.INVALID_CONTAINER_DISCRIMINANT_COLUMN_UPDATE,
                 lhs.getPEColumn().getName().getUnquotedName().get(),
                 lhs.getPEColumn().getTable().getName().getUnquotedName().get()));
     }
     return false;
   } else if (stmt instanceof DeleteStatement) {
     DeleteStatement ds = (DeleteStatement) stmt;
     PETable pet = ds.getTargetDeleteEdge().get().getAbstractTable().asTable();
     if (pet.isContainerBaseTable(sc)) {
       List<Part> parts = DiscriminantCollector.getDiscriminants(sc, ds.getWhereClause());
       if (parts == null || parts.isEmpty())
         throw new SchemaException(
             new ErrorInfo(
                 AvailableErrors.INVALID_CONTAINER_DELETE, pet.getName().getUnquotedName().get()));
       else {
         List<SchemaCacheKey<PEContainerTenant>> matchingTenants = convert(sc, parts);
         stmt.getBlock().store(ContainerBaseTableRewriteTransformFactory.class, matchingTenants);
         return true;
       }
     }
     return false;
   }
   return false;
 }
 private List<SchemaCacheKey<PEContainerTenant>> getPertinentTenants(
     PlannerContext pc, DMLStatement stmt) throws PEException {
   SchemaContext sc = pc.getContext();
   if (stmt instanceof UpdateStatement) {
     UpdateStatement us = (UpdateStatement) stmt;
     for (Iterator<ExpressionNode> iter = us.getUpdateExpressionsEdge().iterator();
         iter.hasNext(); ) {
       FunctionCall fc = (FunctionCall) iter.next();
       ColumnInstance lhs = (ColumnInstance) fc.getParametersEdge().get(0);
       if (lhs.getPEColumn().isPartOfContainerDistributionVector())
         throw new SchemaException(
             Pass.PLANNER,
             "Invalid update: discriminant column "
                 + lhs.getPEColumn().getName().getSQL()
                 + " of container base table "
                 + lhs.getPEColumn().getTable().getName().getSQL()
                 + " cannot be updated");
     }
   } else if (stmt instanceof DeleteStatement) {
     DeleteStatement ds = (DeleteStatement) stmt;
     PETable pet = ds.getTargetDeleteEdge().get().getAbstractTable().asTable();
     if (pet.isContainerBaseTable(sc)) {
       List<Part> parts = DiscriminantCollector.getDiscriminants(sc, ds.getWhereClause());
       if (parts == null || parts.isEmpty())
         throw new SchemaException(
             Pass.PLANNER,
             "Invalid delete on container base table "
                 + pet.getName().getSQL()
                 + ".  Not restricted by discriminant columns");
       else {
         List<SchemaCacheKey<PEContainerTenant>> matchingTenants = convert(sc, parts);
         return matchingTenants;
       }
     }
   }
   return null;
 }