[Bug]fix pad wrong answer (apache#140)

* fix pad wrong answer * add commit to explain pad logic
HappenLee · Sep 7, 2021 · b0f8613 · b0f8613
1 parent c7fe1e3
commit b0f8613
Showing 1 changed file with 21 additions and 0 deletions.
diff --git a/be/src/vec/functions/function_string.h b/be/src/vec/functions/function_string.h
@@ -617,6 +617,8 @@ class FunctionStringPad : public IFunction {
             pad_index.clear();
             buffer.clear();
             if (null_map_data[i] || col_len_data[i] < 0) {
+                // return NULL when input string is NULL or input length is invalid number
+                null_map_data[i] = true;
                 StringOP::push_empty_string(i, res_chars, res_offsets);
             } else {
                 int str_len = strcol_offsets[i] - strcol_offsets[i - 1] - 1;
@@ -632,6 +634,25 @@ class FunctionStringPad : public IFunction {
                 size_t pad_char_size =
                         get_char_len(std::string_view(pad_data, pad_len), &pad_index);
 
+                if (col_len_data[i] <= str_char_size) {
+                    // truncate the input string
+                    if (col_len_data[i] < str_char_size) {
+                        buffer.append(str_data, str_data + str_index[col_len_data[i]]);
+                    } else {
+                        buffer.append(str_data, str_data + str_len);
+                    }
+
+                    StringOP::push_value_string(std::string_view(buffer.data(), buffer.size()), i,
+                                                res_chars, res_offsets);
+                    continue;
+                }
+                if (pad_char_size == 0) {
+                    // return NULL when the string to be paded is missing
+                    null_map_data[i] = true;
+                    StringOP::push_empty_string(i, res_chars, res_offsets);
+                    continue;
+                }
+
                 int32_t pad_byte_len = 0;
                 int32_t pad_times = (col_len_data[i] - str_char_size) / pad_char_size;
                 int32_t pad_remainder = (col_len_data[i] - str_char_size) % pad_char_size;