From 8392b35d5062eb4b62b3041fbb01f58885155d0d Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@clickhouse.com>
Date: Thu, 9 Feb 2023 04:39:12 +0100
Subject: [PATCH] Speed up countDigits

---
 base/base/itoa.h              | 68 ++++++++++++++++++-----------------
 src/Functions/countDigits.cpp | 59 +++++++++---------------------
 2 files changed, 51 insertions(+), 76 deletions(-)

diff --git a/base/base/itoa.h b/base/base/itoa.h
index dd3e3cc96fe..513070c99d9 100644
--- a/base/base/itoa.h
+++ b/base/base/itoa.h
@@ -33,6 +33,41 @@
 #include <base/extended_types.h>
 
 
+template <typename T>
+inline int digits10(T x)
+{
+    if (x < 10ULL)
+        return 1;
+    if (x < 100ULL)
+        return 2;
+    if (x < 1000ULL)
+        return 3;
+
+    if (x < 1000000000000ULL)
+    {
+        if (x < 100000000ULL)
+        {
+            if (x < 1000000ULL)
+            {
+                if (x < 10000ULL)
+                    return 4;
+                else
+                    return 5 + (x >= 100000ULL);
+            }
+
+            return 7 + (x >= 10000000ULL);
+        }
+
+        if (x < 10000000000ULL)
+            return 9 + (x >= 1000000000ULL);
+
+        return 11 + (x >= 100000000000ULL);
+    }
+
+    return 12 + digits10(x / 1000000000000ULL);
+}
+
+
 namespace impl
 {
 
@@ -312,39 +347,6 @@ namespace convert
     }
 }
 
-template <typename T>
-static inline int digits10(T x)
-{
-    if (x < 10ULL)
-        return 1;
-    if (x < 100ULL)
-        return 2;
-    if (x < 1000ULL)
-        return 3;
-
-    if (x < 1000000000000ULL)
-    {
-        if (x < 100000000ULL)
-        {
-            if (x < 1000000ULL)
-            {
-                if (x < 10000ULL)
-                    return 4;
-                else
-                    return 5 + (x >= 100000ULL);
-            }
-
-            return 7 + (x >= 10000000ULL);
-        }
-
-        if (x < 10000000000ULL)
-            return 9 + (x >= 1000000000ULL);
-
-        return 11 + (x >= 100000000000ULL);
-    }
-
-    return 12 + digits10(x / 1000000000000ULL);
-}
 
 template <typename T>
 static inline char * writeUIntText(T x, char * p)
diff --git a/src/Functions/countDigits.cpp b/src/Functions/countDigits.cpp
index aefe0d92d94..2ca8d944b0a 100644
--- a/src/Functions/countDigits.cpp
+++ b/src/Functions/countDigits.cpp
@@ -2,9 +2,10 @@
 #include <Functions/FunctionFactory.h>
 #include <Functions/FunctionHelpers.h>
 #include <DataTypes/DataTypesNumber.h>
-#include <DataTypes/DataTypesDecimal.h>
 #include <Columns/ColumnsNumber.h>
 #include <Columns/ColumnDecimal.h>
+#include <base/extended_types.h>
+#include <base/itoa.h>
 
 
 namespace DB
@@ -83,7 +84,7 @@ private:
     template <typename T, typename ColVecType>
     static void execute(const ColVecType & col, ColumnUInt8 & result_column, size_t rows_count)
     {
-        using NativeT = NativeType<T>;
+        using NativeT = make_unsigned_t<NativeType<T>>;
 
         const auto & src_data = col.getData();
         auto & dst_data = result_column.getData();
@@ -92,50 +93,22 @@ private:
         for (size_t i = 0; i < rows_count; ++i)
         {
             if constexpr (is_decimal<T>)
-                dst_data[i] = digits<NativeT>(src_data[i].value);
-            else
-                dst_data[i] = digits<NativeT>(src_data[i]);
-        }
-    }
-
-    template <typename T>
-    static UInt32 digits(T value)
-    {
-        static_assert(!is_decimal<T>);
-        using DivT = std::conditional_t<is_signed_v<T>, Int32, UInt32>;
-
-        UInt32 res = 0;
-        T tmp;
-
-        if constexpr (sizeof(T) > sizeof(Int32))
-        {
-            static constexpr const DivT e9 = 1000000000;
-
-            tmp = value / e9;
-            while (tmp != 0)
             {
-                value = tmp;
-                tmp /= e9;
-                res += 9;
+                auto value = src_data[i].value;
+                if (unlikely(value < 0))
+                    dst_data[i] = digits10<NativeT>(-static_cast<NativeT>(value));
+                else
+                    dst_data[i] = digits10<NativeT>(value);
+            }
+            else
+            {
+                auto value = src_data[i];
+                if (unlikely(value < 0))
+                    dst_data[i] = digits10<NativeT>(-static_cast<NativeT>(value));
+                else
+                    dst_data[i] = digits10<NativeT>(value);
             }
         }
-
-        static constexpr const DivT e3 = 1000;
-
-        tmp = value / e3;
-        while (tmp != 0)
-        {
-            value = tmp;
-            tmp /= e3;
-            res += 3;
-        }
-
-        while (value != 0)
-        {
-            value /= 10;
-            ++res;
-        }
-        return res;
     }
 };