Remove unnecessary duplicated removal of ordering predicates (#1509)

buildKeysIterationPlan removes ordering predicates from an expression before planning. During planning buildPlanForExpressions is called, which repeats removing ordering predicates without consistently using the result.

To reduce unnecessary duplicated removal it's removed from buildPlanForExpressions and replaced with an assertion. Also its visibility is reduced from public to default as it's called within the package only.

Author: k-rus

src/java/org/apache/cassandra/index/sai/plan/QueryController.java

@@ -519,16 +519,15 @@ private Plan.KeysIteration buildInequalityPlan(Expression predicate)
      * @param builder The plan node builder which receives the built index scans
      * @param expressions The expressions to build the plan from
      */
-    public void buildPlanForExpressions(Plan.Builder builder, Collection<Expression> expressions)
+    void buildPlanForExpressions(Plan.Builder builder, Collection<Expression> expressions)
     {
         Operation.OperationType op = builder.type;
         assert !expressions.isEmpty() : "expressions should not be empty for " + op + " in " + command.rowFilter().root();
 
-        // VSTODO move ANN out of expressions and into its own abstraction? That will help get generic ORDER BY support
-        Collection<Expression> exp = expressions.stream().filter(e -> e.operation != Expression.Op.ORDER_BY).collect(Collectors.toList());
+        assert !expressions.stream().anyMatch(e -> e.operation == Expression.Op.ORDER_BY);
 
         // we cannot use indexes with OR if we have a mix of indexed and non-indexed columns (see CNDB-10142)
-        if (op == Operation.OperationType.OR && !exp.stream().allMatch(e -> e.context.isIndexed()))
+        if (op == Operation.OperationType.OR && !expressions.stream().allMatch(e -> e.context.isIndexed()))
         {
             builder.add(planFactory.everything);
             return;