Github user twdsilva commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/417#discussion_r244065522
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/util/ExpressionUtil.java ---
@@ -68,4 +76,144 @@ public static boolean isPkPositionChanging(TableRef
tableRef, List<Expression> p
return false;
}
+ /**
+ * check the whereExpression to see if the columnExpression is
constant.
+ * eg. for "where a =3 and b > 9", a is constant,but b is not.
+ * @param columnExpression
+ * @param whereExpression
+ * @return
+ */
+ public static boolean isColumnExpressionConstant(ColumnExpression
columnExpression, Expression whereExpression) {
+ if(whereExpression == null) {
+ return false;
+ }
+ IsColumnConstantExpressionVisitor
isColumnConstantExpressionVisitor =
+ new IsColumnConstantExpressionVisitor(columnExpression);
+ whereExpression.accept(isColumnConstantExpressionVisitor);
+ return isColumnConstantExpressionVisitor.isConstant();
+ }
+
+ private static class IsColumnConstantExpressionVisitor extends
StatelessTraverseNoExpressionVisitor<Void> {
+ private final Expression columnExpression ;
+ private Expression firstRhsConstantExpression = null;
+ private int rhsConstantCount = 0;
+ private boolean isNullExpressionVisited = false;
+
+ public IsColumnConstantExpressionVisitor(Expression
columnExpression) {
+ this.columnExpression = columnExpression;
+ }
+ /**
+ * only conside and,for "where a = 3 or b = 9", neither a or b is
constant.
+ */
+ @Override
+ public Iterator<Expression> visitEnter(AndExpression
andExpression) {
+ if(rhsConstantCount > 1) {
+ return null;
+ }
+ return andExpression.getChildren().iterator();
+ }
+ /**
+ * <pre>
+ * We just conside {@link ComparisonExpression} because:
--- End diff --
nit: only consider
---
