udsf-get-output-range.md


    /*
     * This method computes the output range for this scalar function from
     *   the ranges of its inputs in a single invocation.
     *
     * The input ranges are retrieved via inRange
     * The output range is returned via outRange
     */
    virtual void getOutputRange(Vertica::ServerInterface &srvInterface,
                                Vertica::ValueRangeReader &inRange,
                                Vertica::ValueRangeWriter &outRange)
    {
        if (inRange.hasBounds(0) && inRange.hasBounds(1)) {
            // Input ranges have bounds defined
            if (inRange.isNull(0) || inRange.isNull(1)) {
                // At least one range has only NULL values.
                // Output range can only have NULL values.
                outRange.setNull();
                outRange.setHasBounds();
                return;
            } else {
                // Compute output range
                const vint& a1LoBound = inRange.getIntRefLo(0);
                const vint& a2LoBound = inRange.getIntRefLo(1);
                outRange.setIntLo(a1LoBound + a2LoBound);

                const vint& a1UpBound = inRange.getIntRefUp(0);
                const vint& a2UpBound = inRange.getIntRefUp(1);
                outRange.setIntUp(a1UpBound + a2UpBound);
            }
        } else {
            // Input ranges are unbounded. No output range can be defined
            return;
        }

        if (!inRange.canHaveNulls(0) && !inRange.canHaveNulls(1)) {
            // There cannot be NULL values in the output range
            outRange.setCanHaveNulls(false);
        }

        // Let Vertica know that the output range is bounded
        outRange.setHasBounds();
    }