perf(sparksql): eliminate data copy in unscaled_value

bolt/functions/sparksql/UnscaledValueFunction.cpp

@@ -47,15 +47,23 @@ class UnscaledValueFunction final : public exec::VectorFunction {
         args[0]->type()->isShortDecimal(),
         "Expect short decimal type, but got: {}",
         args[0]->type());
-    exec::DecodedArgs decodedArgs(rows, args, context);
-    auto decimalVector = decodedArgs.at(0);
-    context.ensureWritable(rows, BIGINT(), result);
-    result->clearNulls(rows);
-    auto flatResult =
-        result->asUnchecked<FlatVector<int64_t>>()->mutableRawValues();
-    rows.applyToSelected([&](auto row) {
-      flatResult[row] = decimalVector->valueAt<int64_t>(row);
-    });
+    VectorPtr localResult;
+    const auto& arg = args[0];
+    if (arg->isConstantEncoding()) {
+      auto value = arg->as<ConstantVector<int64_t>>()->valueAt(0);
+      localResult = std::make_shared<ConstantVector<int64_t>>(
+          context.pool(), rows.end(), false, BIGINT(), std::move(value));
+    } else {
+      auto flatInput = arg->asFlatVector<int64_t>();
+      localResult = std::make_shared<FlatVector<int64_t>>(
+          context.pool(),
+          BIGINT(),
+          nullptr,
+          rows.end(),
+          flatInput->values(),
+          std::vector<BufferPtr>());
+    }
+    context.moveOrCopyResult(localResult, rows, result);
   }
 };
 } // namespace

bolt/functions/sparksql/tests/UnscaledValueFunctionTest.cpp

@@ -37,18 +37,18 @@ namespace {
 class UnscaledValueFunctionTest : public SparkFunctionBaseTest {};
 
 TEST_F(UnscaledValueFunctionTest, unscaledValue) {
-  auto testUnscaledValue = [&](const std::vector<int64_t>& unscaledValue,
-                               const TypePtr& decimalType) {
-    auto input = makeFlatVector<int64_t>(unscaledValue, decimalType);
-    auto expected = makeFlatVector<int64_t>(unscaledValue);
-    auto result = evaluate("unscaled_value(c0)", makeRowVector({input}));
-    assertEqualVectors(expected, result);
-  };
+  auto input =
+      makeFlatVector<int64_t>({1000, 2000, -3000, -4000}, DECIMAL(18, 3));
+  auto expected = makeFlatVector<int64_t>({1000, 2000, -3000, -4000});
+  auto invalidInput = makeFlatVector<int64_t>({0, 0, 0, 0}, DECIMAL(20, 3));
 
-  testUnscaledValue({1000, 2000, -3000, -4000}, DECIMAL(18, 3));
+  testEncodings(
+      makeTypedExpr("unscaled_value(c0)", ROW({"c0"}, {input->type()})),
+      {input},
+      expected);
 
-  BOLT_ASSERT_THROW(
-      testUnscaledValue({1000, 2000, -3000, -4000}, DECIMAL(20, 3)),
+  BOLT_ASSERT_USER_THROW(
+      evaluate("unscaled_value(c0)", makeRowVector({invalidInput})),
       "Expect short decimal type, but got: DECIMAL(20, 3)");
 }