Improve the performance of length and ascii functions (#9345)

close #9344

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>

dbms/src/Functions/FunctionsNull.h

@@ -64,7 +64,7 @@ class FunctionCoalesce : public IFunction
 public:
     static constexpr auto name = "coalesce";
     static FunctionPtr create(const Context & context);
-    FunctionCoalesce(const Context & context)
+    explicit FunctionCoalesce(const Context & context)
         : context(context)
     {}
 

dbms/src/Functions/FunctionsString.cpp

@@ -13,6 +13,8 @@
 // limitations under the License.
 
 #include <Columns/ColumnArray.h>
+#include <Columns/ColumnsNumber.h>
+#include <Columns/IColumn.h>
 #include <Common/TargetSpecific.h>
 #include <Common/UTF8Helpers.h>
 #include <Common/Volnitsky.h>
@@ -4474,9 +4476,11 @@ class FunctionASCII : public IFunction
     std::string getName() const override { return name; }
     size_t getNumberOfArguments() const override { return 1; }
 
+    bool useDefaultImplementationForConstants() const override { return true; }
+
     DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
     {
-        if (arguments.size() != 1)
+        if unlikely (arguments.size() != 1)
             throw Exception(
                 fmt::format(
                     "Number of arguments for function {} doesn't match: passed {}, should be 1.",
@@ -4490,30 +4494,25 @@ class FunctionASCII : public IFunction
     void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result) const override
     {
         const IColumn * c0_col = block.getByPosition(arguments[0]).column.get();
-        const auto * c0_const = checkAndGetColumn<ColumnConst>(c0_col);
         const auto * c0_string = checkAndGetColumn<ColumnString>(c0_col);
-
-        Field res_field;
-        int val_num = c0_col->size();
-        auto col_res = ColumnInt64::create();
-        col_res->reserve(val_num);
-        if (c0_const == nullptr && c0_string == nullptr)
+        if unlikely (c0_string == nullptr)
             throw Exception(
                 fmt::format("Illegal argument of function {}", getName()),
                 ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
 
-        for (int i = 0; i < val_num; i++)
-        {
-            c0_col->get(i, res_field);
-            String handled_str = res_field.get<String>();
-            Int64 res = handled_str.empty() ? 0 : static_cast<Int64>(handled_str[0]);
-            col_res->insert(res);
-        }
+        auto val_num = static_cast<ssize_t>(c0_col->size());
+        auto col_res = ColumnInt64::create();
+        ColumnInt64::Container & data = col_res->getData();
+        data.resize(val_num);
+
+        const auto & chars = c0_string->getChars();
+        const auto & offsets = c0_string->getOffsets();
+
+        for (ssize_t i = 0; i < val_num; i++)
+            data[i] = chars[offsets[i - 1]];
 
         block.getByPosition(result).column = std::move(col_res);
     }
-
-private:
 };
 
 class FunctionLength : public IFunction
@@ -4527,9 +4526,11 @@ class FunctionLength : public IFunction
     std::string getName() const override { return name; }
     size_t getNumberOfArguments() const override { return 1; }
 
+    bool useDefaultImplementationForConstants() const override { return true; }
+
     DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
     {
-        if (arguments.size() != 1)
+        if unlikely (arguments.size() != 1)
             throw Exception(
                 fmt::format(
                     "Number of arguments for function {} doesn't match: passed {}, should be 1.",
@@ -4543,24 +4544,21 @@ class FunctionLength : public IFunction
     void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result) const override
     {
         const IColumn * c0_col = block.getByPosition(arguments[0]).column.get();
-        const auto * c0_const = checkAndGetColumn<ColumnConst>(c0_col);
         const auto * c0_string = checkAndGetColumn<ColumnString>(c0_col);
-
-        Field res_field;
-        int val_num = c0_col->size();
-        auto col_res = ColumnInt64::create();
-        col_res->reserve(val_num);
-        if (c0_const == nullptr && c0_string == nullptr)
+        if unlikely (c0_string == nullptr)
             throw Exception(
                 fmt::format("Illegal argument of function {}", getName()),
                 ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
 
-        for (int i = 0; i < val_num; i++)
-        {
-            c0_col->get(i, res_field);
-            String handled_str = res_field.get<String>();
-            col_res->insert(static_cast<Int64>(handled_str.size()));
-        }
+        auto val_num = static_cast<ssize_t>(c0_col->size());
+        auto col_res = ColumnInt64::create();
+        ColumnInt64::Container & data = col_res->getData();
+        data.resize(val_num);
+
+        const auto & offsets = c0_string->getOffsets();
+
+        for (ssize_t i = 0; i < val_num; i++)
+            data[i] = offsets[i] - offsets[i - 1] - 1;
 
         block.getByPosition(result).column = std::move(col_res);
     }

dbms/src/Functions/GatherUtils/Algorithms.h

@@ -192,7 +192,7 @@ void concat(const std::vector<std::unique_ptr<IArraySource>> & array_sources, Si
     size_t sources_num = array_sources.size();
     std::vector<char> is_const(sources_num);
 
-    auto checkAndGetSizeToReserve = [](auto source, IArraySource * array_source) {
+    auto check_and_get_size_to_reserve = [](auto source, IArraySource * array_source) {
         if (source == nullptr)
             throw Exception(
                 "Concat function expected " + demangle(typeid(Source).name()) + " or "
@@ -205,17 +205,18 @@ void concat(const std::vector<std::unique_ptr<IArraySource>> & array_sources, Si
     size_t size_to_reserve = 0;
     for (auto i : ext::range(0, sources_num))
     {
-        auto & source = array_sources[i];
+        const auto & source = array_sources[i];
         is_const[i] = source->isConst();
         if (is_const[i])
-            size_to_reserve += checkAndGetSizeToReserve(typeid_cast<ConstSource<Source> *>(source.get()), source.get());
+            size_to_reserve
+                += check_and_get_size_to_reserve(typeid_cast<ConstSource<Source> *>(source.get()), source.get());
         else
-            size_to_reserve += checkAndGetSizeToReserve(typeid_cast<Source *>(source.get()), source.get());
+            size_to_reserve += check_and_get_size_to_reserve(typeid_cast<Source *>(source.get()), source.get());
     }
 
     sink.reserve(size_to_reserve);
 
-    auto writeNext = [&sink](auto source) {
+    auto write_next = [&sink](auto source) {
         writeSlice(source->getWhole(), sink);
         source->next();
     };
@@ -224,11 +225,11 @@ void concat(const std::vector<std::unique_ptr<IArraySource>> & array_sources, Si
     {
         for (auto i : ext::range(0, sources_num))
         {
-            auto & source = array_sources[i];
+            const auto & source = array_sources[i];
             if (is_const[i])
-                writeNext(static_cast<ConstSource<Source> *>(source.get()));
+                write_next(static_cast<ConstSource<Source> *>(source.get()));
             else
-                writeNext(static_cast<Source *>(source.get()));
+                write_next(static_cast<Source *>(source.get()));
         }
         sink.next();
     }
@@ -389,11 +390,11 @@ void NO_INLINE pad(SourceA && src, SourceB && padding, Sink && sink, ssize_t len
             size_t left = static_cast<size_t>(length) - slice.size;
             if (is_left)
             {
-                StringSource::Slice padSlice = padding.getWhole();
-                while (left > padSlice.size && padSlice.size != 0)
+                StringSource::Slice pad_slice = padding.getWhole();
+                while (left > pad_slice.size && pad_slice.size != 0)
                 {
-                    writeSlice(padSlice, sink);
-                    left -= padSlice.size;
+                    writeSlice(pad_slice, sink);
+                    left -= pad_slice.size;
                 }
 
                 writeSlice(padding.getSliceFromLeft(0, left), sink);
@@ -402,11 +403,11 @@ void NO_INLINE pad(SourceA && src, SourceB && padding, Sink && sink, ssize_t len
             else
             {
                 writeSlice(slice, sink);
-                StringSource::Slice padSlice = padding.getWhole();
-                while (left > padSlice.size && padSlice.size != 0)
+                StringSource::Slice pad_slice = padding.getWhole();
+                while (left > pad_slice.size && pad_slice.size != 0)
                 {
-                    writeSlice(padSlice, sink);
-                    left -= padSlice.size;
+                    writeSlice(pad_slice, sink);
+                    left -= pad_slice.size;
                 }
 
                 writeSlice(padding.getSliceFromLeft(0, left), sink);

dbms/src/Functions/tests/bench_function_ilike.cpp → dbms/src/Functions/tests/bench_function_string.cpp

@@ -17,8 +17,8 @@
 #include <TestUtils/FunctionTestUtils.h>
 #include <benchmark/benchmark.h>
 
-/// this is a hack, include the cpp file so we can test MatchImpl directly
-#include <Functions/FunctionsString.cpp>
+/// this is a hack, include the cpp file so we can test functions directly
+#include <Functions/FunctionsString.cpp> // NOLINT
 #include <Functions/FunctionsStringSearch.cpp> // NOLINT
 
 namespace DB
@@ -306,5 +306,65 @@ BENCH_LIKE_COLLATOR(ASCII_BIN);
 BENCH_LIKE_COLLATOR(BINARY);
 BENCH_LIKE_COLLATOR(LATIN1_BIN);
 
+class LengthBench : public benchmark::Fixture
+{
+public:
+    using ColStringType = typename TypeTraits<String>::FieldType;
+
+    ColumnsWithTypeAndName data1{toVec<String>("col", std::vector<ColStringType>(data_num, ""))};
+    ColumnsWithTypeAndName data2{toVec<String>("col", std::vector<ColStringType>(data_num, "aaaaaaaaaa"))};
+    ColumnsWithTypeAndName data3{toVec<String>("col", std::vector<ColStringType>(data_num, "啊aaaaaaaa"))};
+
+    void SetUp(const benchmark::State &) override {}
+};
+
+BENCHMARK_DEFINE_F(LengthBench, bench)
+(benchmark::State & state)
+try
+{
+    FunctionLength function_length;
+    std::vector<Block> blocks{Block(data1), Block(data2), Block(data3)};
+    for (auto & block : blocks)
+        block.insert({nullptr, std::make_shared<DataTypeNumber<UInt8>>(), "res"});
+    ColumnNumbers arguments{0};
+    for (auto _ : state)
+    {
+        for (auto & block : blocks)
+            function_length.executeImpl(block, arguments, 1);
+    }
+}
+CATCH
+BENCHMARK_REGISTER_F(LengthBench, bench)->Iterations(10);
+
+class ASCIIBench : public benchmark::Fixture
+{
+public:
+    using ColStringType = typename TypeTraits<String>::FieldType;
+
+    ColumnsWithTypeAndName data1{toVec<String>("col", std::vector<ColStringType>(data_num, ""))};
+    ColumnsWithTypeAndName data2{toVec<String>("col", std::vector<ColStringType>(data_num, "aaaaaaaaaa"))};
+    ColumnsWithTypeAndName data3{toVec<String>("col", std::vector<ColStringType>(data_num, "啊aaaaaaaa"))};
+
+    void SetUp(const benchmark::State &) override {}
+};
+
+BENCHMARK_DEFINE_F(ASCIIBench, bench)
+(benchmark::State & state)
+try
+{
+    FunctionASCII function_ascii;
+    std::vector<Block> blocks{Block(data1), Block(data2), Block(data3)};
+    for (auto & block : blocks)
+        block.insert({nullptr, std::make_shared<DataTypeNumber<UInt8>>(), "res"});
+    ColumnNumbers arguments{0};
+    for (auto _ : state)
+    {
+        for (auto & block : blocks)
+            function_ascii.executeImpl(block, arguments, 1);
+    }
+}
+CATCH
+BENCHMARK_REGISTER_F(ASCIIBench, bench)->Iterations(10);
+
 } // namespace tests
 } // namespace DB