Change how short circuit optimization works

src/Columns/MaskOperations.cpp

@@ -279,25 +279,32 @@ void maskedExecute(ColumnWithTypeAndName & column, const PaddedPODArray<UInt8> &
     if (!column_function)
         return;
 
+    size_t original_size = column.column->size();
+
     ColumnWithTypeAndName result;
-    /// If mask contains only zeros, we can just create
-    /// an empty column with the execution result type.
     if (!mask_info.has_ones)
     {
+        /// If mask contains only zeros, we can just create a column with default values as it will be ignored
         auto result_type = column_function->getResultType();
-        auto empty_column = result_type->createColumn();
+        auto default_column = result_type->createColumnConstWithDefaultValue(original_size)->convertToFullColumnIfConst();
-        result = {std::move(empty_column), result_type, ""};
+        column = {std::move(default_column), result_type, ""};
     }
-    /// Filter column only if mask contains zeros.
     else if (mask_info.has_zeros)
     {
+        /// If it contains both zeros and ones, we need to execute the function only on the mask values
+        /// First we filter the column, which creates a new column, then we apply the column, and finally we expand it
+        /// Expanding is done to keep consistency in function calls (all columns the same size) and it's ok
+        /// since the values won't be used by `if`
         auto filtered = column_function->filter(mask, -1);
-        result = typeid_cast<const ColumnFunction *>(filtered.get())->reduce();
+        auto filter_after_execution = typeid_cast<const ColumnFunction *>(filtered.get())->reduce();
+        auto mut_column = IColumn::mutate(std::move(filter_after_execution.column));
+        mut_column->expand(mask, false);
+        column.column = std::move(mut_column);
     }
     else
-        result = column_function->reduce();
+        column = column_function->reduce();
 
-    column = std::move(result);
+    chassert(column.column->size() == original_size);
 }
 
 void executeColumnIfNeeded(ColumnWithTypeAndName & column, bool empty)

src/Functions/if.cpp

@@ -76,63 +76,6 @@ inline void fillVectorVector(const ArrayCond & cond, const ArrayA & a, const Arr
 {
 
     size_t size = cond.size();
-    bool a_is_short = a.size() < size;
-    bool b_is_short = b.size() < size;
-
-    if (a_is_short && b_is_short)
-    {
-        size_t a_index = 0, b_index = 0;
-        for (size_t i = 0; i < size; ++i)
-        {
-            if constexpr (is_native_int_or_decimal_v<ResultType>)
-                res[i] = !!cond[i] * static_cast<ResultType>(a[a_index]) + (!cond[i]) * static_cast<ResultType>(b[b_index]);
-            else if constexpr (std::is_floating_point_v<ResultType>)
-            {
-                BRANCHFREE_IF_FLOAT(ResultType, cond[i], a[a_index], b[b_index], res[i])
-            }
-            else
-                res[i] = cond[i] ? static_cast<ResultType>(a[a_index]) : static_cast<ResultType>(b[b_index]);
-
-            a_index += !!cond[i];
-            b_index += !cond[i];
-        }
-    }
-    else if (a_is_short)
-    {
-        size_t a_index = 0;
-        for (size_t i = 0; i < size; ++i)
-        {
-            if constexpr (is_native_int_or_decimal_v<ResultType>)
-                res[i] = !!cond[i] * static_cast<ResultType>(a[a_index]) + (!cond[i]) * static_cast<ResultType>(b[i]);
-            else if constexpr (std::is_floating_point_v<ResultType>)
-            {
-                BRANCHFREE_IF_FLOAT(ResultType, cond[i], a[a_index], b[i], res[i])
-            }
-            else
-                res[i] = cond[i] ? static_cast<ResultType>(a[a_index]) : static_cast<ResultType>(b[i]);
-
-            a_index += !!cond[i];
-        }
-    }
-    else if (b_is_short)
-    {
-        size_t b_index = 0;
-        for (size_t i = 0; i < size; ++i)
-        {
-            if constexpr (is_native_int_or_decimal_v<ResultType>)
-                res[i] = !!cond[i] * static_cast<ResultType>(a[i]) + (!cond[i]) * static_cast<ResultType>(b[b_index]);
-            else if constexpr (std::is_floating_point_v<ResultType>)
-            {
-                BRANCHFREE_IF_FLOAT(ResultType, cond[i], a[i], b[b_index], res[i])
-            }
-            else
-                res[i] = cond[i] ? static_cast<ResultType>(a[i]) : static_cast<ResultType>(b[b_index]);
-
-            b_index += !cond[i];
-        }
-    }
-    else
-    {
     for (size_t i = 0; i < size; ++i)
     {
         if constexpr (is_native_int_or_decimal_v<ResultType>)
@@ -146,33 +89,12 @@ inline void fillVectorVector(const ArrayCond & cond, const ArrayA & a, const Arr
             res[i] = cond[i] ? static_cast<ResultType>(a[i]) : static_cast<ResultType>(b[i]);
         }
     }
-    }
 }
 
 template <typename ArrayCond, typename ArrayA, typename B, typename ArrayResult, typename ResultType>
 inline void fillVectorConstant(const ArrayCond & cond, const ArrayA & a, B b, ArrayResult & res)
 {
     size_t size = cond.size();
-    bool a_is_short = a.size() < size;
-    if (a_is_short)
-    {
-        size_t a_index = 0;
-        for (size_t i = 0; i < size; ++i)
-        {
-            if constexpr (is_native_int_or_decimal_v<ResultType>)
-                res[i] = !!cond[i] * static_cast<ResultType>(a[a_index]) + (!cond[i]) * static_cast<ResultType>(b);
-            else if constexpr (std::is_floating_point_v<ResultType>)
-            {
-                BRANCHFREE_IF_FLOAT(ResultType, cond[i], a[a_index], b, res[i])
-            }
-            else
-                res[i] = cond[i] ? static_cast<ResultType>(a[a_index]) : static_cast<ResultType>(b);
-
-            a_index += !!cond[i];
-        }
-    }
-    else
-    {
     for (size_t i = 0; i < size; ++i)
     {
         if constexpr (is_native_int_or_decimal_v<ResultType>)
@@ -184,33 +106,12 @@ inline void fillVectorConstant(const ArrayCond & cond, const ArrayA & a, B b, Ar
         else
             res[i] = cond[i] ? static_cast<ResultType>(a[i]) : static_cast<ResultType>(b);
     }
-    }
 }
 
 template <typename ArrayCond, typename A, typename ArrayB, typename ArrayResult, typename ResultType>
 inline void fillConstantVector(const ArrayCond & cond, A a, const ArrayB & b, ArrayResult & res)
 {
     size_t size = cond.size();
-    bool b_is_short = b.size() < size;
-    if (b_is_short)
-    {
-        size_t b_index = 0;
-        for (size_t i = 0; i < size; ++i)
-        {
-            if constexpr (is_native_int_or_decimal_v<ResultType>)
-                res[i] = !!cond[i] * static_cast<ResultType>(a) + (!cond[i]) * static_cast<ResultType>(b[b_index]);
-            else if constexpr (std::is_floating_point_v<ResultType>)
-            {
-                BRANCHFREE_IF_FLOAT(ResultType, cond[i], a, b[b_index], res[i])
-            }
-            else
-                res[i] = cond[i] ? static_cast<ResultType>(a) : static_cast<ResultType>(b[b_index]);
-
-            b_index += !cond[i];
-        }
-    }
-    else
-    {
     for (size_t i = 0; i < size; ++i)
     {
         if constexpr (is_native_int_or_decimal_v<ResultType>)
@@ -222,7 +123,6 @@ inline void fillConstantVector(const ArrayCond & cond, A a, const ArrayB & b, Ar
         else
             res[i] = cond[i] ? static_cast<ResultType>(a) : static_cast<ResultType>(b[i]);
     }
-    }
 }
 
 template <typename ArrayCond, typename A, typename B, typename ArrayResult, typename ResultType>
@@ -879,9 +779,6 @@ private:
         bool then_is_const = isColumnConst(*col_then);
         bool else_is_const = isColumnConst(*col_else);
 
-        bool then_is_short = col_then->size() < cond_col->size();
-        bool else_is_short = col_else->size() < cond_col->size();
-
         const auto & cond_array = cond_col->getData();
 
         if (then_is_const && else_is_const)
@@ -901,37 +798,34 @@ private:
         {
             const IColumn & then_nested_column = assert_cast<const ColumnConst &>(*col_then).getDataColumn();
 
-            size_t else_index = 0;
             for (size_t i = 0; i < input_rows_count; ++i)
             {
                 if (cond_array[i])
                     result_column->insertFrom(then_nested_column, 0);
                 else
-                    result_column->insertFrom(*col_else, else_is_short ? else_index++ : i);
+                    result_column->insertFrom(*col_else, i);
             }
         }
         else if (else_is_const)
         {
             const IColumn & else_nested_column = assert_cast<const ColumnConst &>(*col_else).getDataColumn();
 
-            size_t then_index = 0;
             for (size_t i = 0; i < input_rows_count; ++i)
             {
                 if (cond_array[i])
-                    result_column->insertFrom(*col_then, then_is_short ? then_index++ : i);
+                    result_column->insertFrom(*col_then, i);
                 else
                     result_column->insertFrom(else_nested_column, 0);
             }
         }
         else
         {
-            size_t then_index = 0, else_index = 0;
             for (size_t i = 0; i < input_rows_count; ++i)
             {
                 if (cond_array[i])
-                    result_column->insertFrom(*col_then, then_is_short ? then_index++ : i);
+                    result_column->insertFrom(*col_then, i);
                 else
-                    result_column->insertFrom(*col_else, else_is_short ? else_index++ : i);
+                    result_column->insertFrom(*col_else, i);
             }
         }
 
@@ -1124,9 +1018,6 @@ private:
         if (then_is_null && else_is_null)
             return result_type->createColumnConstWithDefaultValue(input_rows_count);
 
-        bool then_is_short = arg_then.column->size() < arg_cond.column->size();
-        bool else_is_short = arg_else.column->size() < arg_cond.column->size();
-
         const ColumnUInt8 * cond_col = typeid_cast<const ColumnUInt8 *>(arg_cond.column.get());
         const ColumnConst * cond_const_col = checkAndGetColumnConst<ColumnVector<UInt8>>(arg_cond.column.get());
 
@@ -1145,8 +1036,6 @@ private:
             {
                 arg_else_column = arg_else_column->convertToFullColumnIfConst();
                 auto result_column = IColumn::mutate(std::move(arg_else_column));
-                if (else_is_short)
-                    result_column->expand(cond_col->getData(), true);
                 if (isColumnNullable(*result_column))
                 {
                     assert_cast<ColumnNullable &>(*result_column).applyNullMap(assert_cast<const ColumnUInt8 &>(*arg_cond.column));
@@ -1187,8 +1076,6 @@ private:
             {
                 arg_then_column = arg_then_column->convertToFullColumnIfConst();
                 auto result_column = IColumn::mutate(std::move(arg_then_column));
-                if (then_is_short)
-                    result_column->expand(cond_col->getData(), false);
 
                 if (isColumnNullable(*result_column))
                 {

tests/queries/0_stateless/02950_dictionary_short_circuit.sql

@@ -1,6 +1,4 @@
--- Tags: no-parallel, disabled
+-- Tags: no-parallel
-
--- Disabled while I investigate so CI keeps running (but it's broken)
 
 DROP TABLE IF EXISTS dictionary_source_table;
 CREATE TABLE dictionary_source_table