Add reinterpretAsUUID function

src/Common/Exception.h

@@ -39,8 +39,11 @@ public:
     const char * name() const throw() override { return "DB::Exception"; }
     const char * what() const throw() override { return message().data(); }
 
-    /// Add something to the existing message.
+    template <typename ...Fmt>
-    void addMessage(const std::string & arg) { extendedMessage(arg); }
+    void addMessage(Fmt&&... fmt)
+    {
+        extendedMessage(fmt::format(std::forward<Fmt>(fmt)...));
+    }
 
     std::string getStackTraceString() const;
 

src/Core/BaseSettings.h

@@ -390,13 +390,21 @@ String BaseSettings<Traits_>::valueToStringUtil(const std::string_view & name, c
 template <typename Traits_>
 Field BaseSettings<Traits_>::stringToValueUtil(const std::string_view & name, const String & str)
 {
-    const auto & accessor = Traits::Accessor::instance();
+    try
-    if (size_t index = accessor.find(name); index != static_cast<size_t>(-1))
+    {
-        return accessor.stringToValueUtil(index, str);
+        const auto & accessor = Traits::Accessor::instance();
-    if constexpr (Traits::allow_custom_settings)
+        if (size_t index = accessor.find(name); index != static_cast<size_t>(-1))
-        return Field::restoreFromDump(str);
+            return accessor.stringToValueUtil(index, str);
-    else
+        if constexpr (Traits::allow_custom_settings)
-        BaseSettingsHelpers::throwSettingNotFound(name);
+            return Field::restoreFromDump(str);
+        else
+            BaseSettingsHelpers::throwSettingNotFound(name);
+    }
+    catch (Exception & e)
+    {
+        e.addMessage("while parsing value '{}' for setting '{}'", str, name);
+        throw;
+    }
 }
 
 template <typename Traits_>

src/Functions/reinterpretStringAs.cpp

@@ -5,6 +5,7 @@
 #include <DataTypes/DataTypeFixedString.h>
 #include <DataTypes/DataTypeDate.h>
 #include <DataTypes/DataTypeDateTime.h>
+#include <DataTypes/DataTypeUUID.h>
 #include <Columns/ColumnString.h>
 #include <Columns/ColumnFixedString.h>
 #include <Columns/ColumnConst.h>
@@ -68,7 +69,7 @@ public:
             size_t offset = 0;
             for (size_t i = 0; i < size; ++i)
             {
-                ToFieldType value = 0;
+                ToFieldType value{};
                 memcpy(&value, &data_from[offset], std::min(static_cast<UInt64>(sizeof(ToFieldType)), offsets_from[i] - offset - 1));
                 vec_res[i] = value;
                 offset = offsets_from[i];
@@ -90,7 +91,7 @@ public:
             size_t copy_size = std::min(step, sizeof(ToFieldType));
             for (size_t i = 0; i < size; ++i)
             {
-                ToFieldType value = 0;
+                ToFieldType value{};
                 memcpy(&value, &data_from[offset], copy_size);
                 vec_res[i] = value;
                 offset += step;
@@ -120,6 +121,7 @@ struct NameReinterpretAsFloat32     { static constexpr auto name = "reinterpretA
 struct NameReinterpretAsFloat64     { static constexpr auto name = "reinterpretAsFloat64"; };
 struct NameReinterpretAsDate        { static constexpr auto name = "reinterpretAsDate"; };
 struct NameReinterpretAsDateTime    { static constexpr auto name = "reinterpretAsDateTime"; };
+struct NameReinterpretAsUUID        { static constexpr auto name = "reinterpretAsUUID"; };
 
 using FunctionReinterpretAsUInt8 = FunctionReinterpretStringAs<DataTypeUInt8,       NameReinterpretAsUInt8>;
 using FunctionReinterpretAsUInt16 = FunctionReinterpretStringAs<DataTypeUInt16,     NameReinterpretAsUInt16>;
@@ -133,6 +135,7 @@ using FunctionReinterpretAsFloat32 = FunctionReinterpretStringAs<DataTypeFloat32
 using FunctionReinterpretAsFloat64 = FunctionReinterpretStringAs<DataTypeFloat64,   NameReinterpretAsFloat64>;
 using FunctionReinterpretAsDate = FunctionReinterpretStringAs<DataTypeDate,         NameReinterpretAsDate>;
 using FunctionReinterpretAsDateTime = FunctionReinterpretStringAs<DataTypeDateTime, NameReinterpretAsDateTime>;
+using FunctionReinterpretAsUUID = FunctionReinterpretStringAs<DataTypeUUID, NameReinterpretAsUUID>;
 
 }
 
@@ -150,6 +153,7 @@ void registerFunctionsReinterpretStringAs(FunctionFactory & factory)
     factory.registerFunction<FunctionReinterpretAsFloat64>();
     factory.registerFunction<FunctionReinterpretAsDate>();
     factory.registerFunction<FunctionReinterpretAsDateTime>();
+    factory.registerFunction<FunctionReinterpretAsUUID>();
 }
 
 }

tests/queries/0_stateless/00396_uuid.reference

@@ -5,3 +5,4 @@
 01234567-89ab-cdef-0123-456789abcdef	01234567-89ab-cdef-0123-456789abcdef	01234567-89ab-cdef-0123-456789abcdef
 01234567-89ab-cdef-0123-456789abcdef	01234567-89ab-cdef-0123-456789abcdef	01234567-89ab-cdef-0123-456789abcdef
 3f1ed72e-f7fe-4459-9cbe-95fe9298f845
+1

tests/queries/0_stateless/00396_uuid.sql

@@ -5,3 +5,9 @@ SELECT hex(UUIDStringToNum(materialize('01234567-89ab-cdef-0123-456789abcdef')))
 SELECT '01234567-89ab-cdef-0123-456789abcdef' AS str, UUIDNumToString(UUIDStringToNum(str)), UUIDNumToString(UUIDStringToNum(toFixedString(str, 36)));
 SELECT materialize('01234567-89ab-cdef-0123-456789abcdef') AS str, UUIDNumToString(UUIDStringToNum(str)), UUIDNumToString(UUIDStringToNum(toFixedString(str, 36)));
 SELECT toString(toUUID('3f1ed72e-f7fe-4459-9cbe-95fe9298f845'));
+
+-- conversion back and forth to big-endian hex string
+with generateUUIDv4() as uuid,
+    identity(lower(hex(reverse(reinterpretAsString(uuid))))) as str,
+    reinterpretAsUUID(reverse(unhex(str))) as uuid2
+select uuid = uuid2;