[GitHub] [incubator-doris] WingsGo commented on a change in pull request #2501: Support more schema change from VARCHAR type

[GitBox <gi...@apache.org>]

WingsGo commented on a change in pull request #2501: Support more schema change from VARCHAR type
URL: https://github.com/apache/incubator-doris/pull/2501#discussion_r361261012
 
 

 ##########
 File path: be/src/olap/types.h
 ##########
 @@ -255,6 +255,36 @@ struct BaseFieldtypeTraits : public CppTypeTraits<field_type> {
     }
 };
 
+template <typename T>
+OLAPStatus convert_int_from_varchar(void* dest, const void* src) {
+    using SrcType = typename CppTypeTraits<OLAP_FIELD_TYPE_VARCHAR>::CppType;
+    auto src_value = reinterpret_cast<const SrcType*>(src);
+    StringParser::ParseResult parse_res;
+    T result = StringParser::string_to_int<T>(src_value->get_data(), src_value->get_size(), &parse_res);
+    if (UNLIKELY(parse_res != StringParser::PARSE_SUCCESS)) {
+        return OLAPStatus::OLAP_ERR_INVALID_SCHEMA;
+    }
+    if (typeid(T) == typeid(CppTypeTraits<OLAP_FIELD_TYPE_LARGEINT>::CppType)) {
 
 Review comment:
   > I think typeid is a runtime operation whose performance may be bad.
   > I think there are two choices for you
   > 
   > 1. write a specialization for largeint
   > 2. use memcpy for all the type
   
   done

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