[branch-2.1](function) fix random_bytes return same data for multi ro…

…ws (#39891) (#40137)

pick #39891

Issue Number: close #xxx

before:
```sql
mysql [optest]>SELECT random_bytes(10) a FROM numbers("number" = "10");
+------------------------+
| a                      |
+------------------------+
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
| 0x7b4e5727024bc5b59e2c |
+------------------------+
```

now:
```sql
mysql [optest]>SELECT random_bytes(10) a FROM numbers("number" = "10");
+------------------------+
| a                      |
+------------------------+
| 0xd82cf60825b29ef2a0fd |
| 0x6f8c808415bdbaa6d257 |
| 0x7c26b5214297a151c25c |
| 0x43f02c77293063900437 |
| 0x5e5727569dec5e24f96b |
| 0x434f20bf74d7759640b7 |
| 0x087ed96b739750c733a6 |
| 0xdf05f6d7ede4972eb846 |
| 0xcefab471912264b5c54f |
| 0x1bddc019409d1926aa10 |
+------------------------+
```

## Proposed changes

Issue Number: close #xxx

<!--Describe your changes.-->

be/src/vec/functions/function_string.h

@@ -3107,31 +3107,37 @@ class FunctionRandomBytes : public IFunction {
         return std::make_shared<DataTypeString>();
     }
 
+    bool use_default_implementation_for_constants() const final { return false; }
+
     Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                         size_t result, size_t input_rows_count) const override {
         auto res = ColumnString::create();
         auto& res_offsets = res->get_offsets();
         auto& res_chars = res->get_chars();
         res_offsets.resize(input_rows_count);
 
-        ColumnPtr argument_column =
-                block.get_by_position(arguments[0]).column->convert_to_full_column_if_const();
-        const auto* length_col = assert_cast<const ColumnInt32*>(argument_column.get());
+        auto [arg_col, arg_const] = unpack_if_const(block.get_by_position(arguments[0]).column);
+        const auto* length_col = assert_cast<const ColumnInt32*>(arg_col.get());
+
+        if (arg_const) {
+            res_chars.reserve(input_rows_count * (length_col->get_element(0) + 2));
+        }
 
         std::vector<uint8_t> random_bytes;
         std::random_device rd;
         std::mt19937 gen(rd());
 
+        std::uniform_int_distribution<unsigned short> distribution(0, 255);
         for (size_t i = 0; i < input_rows_count; ++i) {
-            if (length_col->get_element(i) < 0) [[unlikely]] {
+            size_t index = index_check_const(i, arg_const);
+            if (length_col->get_element(index) < 0) [[unlikely]] {
                 return Status::InvalidArgument("argument {} of function {} at row {} was invalid.",
-                                               length_col->get_element(i), name, i);
+                                               length_col->get_element(index), name, index);
             }
-            random_bytes.resize(length_col->get_element(i));
+            random_bytes.resize(length_col->get_element(index));
 
-            std::uniform_int_distribution<uint8_t> distribution(0, 255);
             for (auto& byte : random_bytes) {
-                byte = distribution(gen);
+                byte = distribution(gen) & 0xFF;
             }
 
             std::ostringstream oss;

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/Random.java

@@ -89,11 +89,6 @@ public boolean nullable() {
         }
     }
 
-    @Override
-    public boolean foldable() {
-        return false;
-    }
-
     /**
      * withChildren.
      */

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/RandomBytes.java

@@ -20,6 +20,7 @@
 import org.apache.doris.catalog.FunctionSignature;
 import org.apache.doris.nereids.trees.expressions.Expression;
 import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
+import org.apache.doris.nereids.trees.expressions.functions.Nondeterministic;
 import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
 import org.apache.doris.nereids.types.IntegerType;
@@ -35,7 +36,7 @@
  * ScalarFunction 'random_bytes'. This class is generated by GenerateFunction.
  */
 public class RandomBytes extends ScalarFunction
-        implements ExplicitlyCastableSignature, PropagateNullable {
+        implements ExplicitlyCastableSignature, PropagateNullable, Nondeterministic {
 
     public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
             FunctionSignature.ret(StringType.INSTANCE).args(IntegerType.INSTANCE),

regression-test/data/nereids_function_p0/scalar_function/R.out

@@ -1125,6 +1125,3 @@ string3
 string3
 string3
 
--- !sql_random_bytes --
-\N
-