Fix json ddl default value

dbms/src/Storages/Transaction/JSONCodec.cpp

@@ -69,16 +69,16 @@ extern const int LOGICAL_ERROR;
 
 using JsonVar = Poco::Dynamic::Var;
 
-constexpr UInt8 TYPE_CODE_OBJECT = 0x01;  // TypeCodeObject indicates the JSON is an object.
-constexpr UInt8 TYPE_CODE_ARRAY = 0x03;   // TypeCodeArray indicates the JSON is an array.
-constexpr UInt8 TYPE_CODE_LITERAL = 0x04; // TypeCodeLiteral indicates the JSON is a literal.
-constexpr UInt8 TYPE_CODE_INT64 = 0x09;   // TypeCodeInt64 indicates the JSON is a signed integer.
-constexpr UInt8 TYPE_CODE_UINT64 = 0x0a;  // TypeCodeUint64 indicates the JSON is a unsigned integer.
-constexpr UInt8 TYPE_CODE_FLOAT64 = 0x0b; // TypeCodeFloat64 indicates the JSON is a double float number.
-constexpr UInt8 TYPE_CODE_STRING = 0x0c;  // TypeCodeString indicates the JSON is a string.
-constexpr UInt8 LITERAL_NIL = 0x00;       // LiteralNil represents JSON null.
-constexpr UInt8 LITERAL_TRUE = 0x01;      // LiteralTrue represents JSON true.
-constexpr UInt8 LITERAL_FALSE = 0x02;     // LiteralFalse represents JSON false.
+extern const UInt8 TYPE_CODE_OBJECT = 0x01;  // TypeCodeObject indicates the JSON is an object.
+extern const UInt8 TYPE_CODE_ARRAY = 0x03;   // TypeCodeArray indicates the JSON is an array.
+extern const UInt8 TYPE_CODE_LITERAL = 0x04; // TypeCodeLiteral indicates the JSON is a literal.
+extern const UInt8 TYPE_CODE_INT64 = 0x09;   // TypeCodeInt64 indicates the JSON is a signed integer.
+extern const UInt8 TYPE_CODE_UINT64 = 0x0a;  // TypeCodeUint64 indicates the JSON is a unsigned integer.
+extern const UInt8 TYPE_CODE_FLOAT64 = 0x0b; // TypeCodeFloat64 indicates the JSON is a double float number.
+extern const UInt8 TYPE_CODE_STRING = 0x0c;  // TypeCodeString indicates the JSON is a string.
+extern const UInt8 LITERAL_NIL = 0x00;       // LiteralNil represents JSON null.
+extern const UInt8 LITERAL_TRUE = 0x01;      // LiteralTrue represents JSON true.
+extern const UInt8 LITERAL_FALSE = 0x02;     // LiteralFalse represents JSON false.
 
 constexpr size_t VALUE_ENTRY_SIZE = 5;
 constexpr size_t KEY_ENTRY_LENGTH = 6;
@@ -212,15 +212,23 @@ String DecodeJsonAsString(size_t & cursor, const String & raw_value)
     return decodeValue(type, cursor, raw_value);
 }
 
-template<bool doDecode>
-struct need_decode{};
+template <bool doDecode>
+struct need_decode
+{
+};
 
 
-template<>
-struct need_decode<true>{ typedef String type; };
+template <>
+struct need_decode<true>
+{
+    typedef String type;
+};
 
-template<>
-struct need_decode<false>{ typedef void type; };
+template <>
+struct need_decode<false>
+{
+    typedef void type;
+};
 
 template <bool doDecode>
 typename need_decode<doDecode>::type DecodeJson(size_t & cursor, const String & raw_value)
@@ -263,14 +271,8 @@ typename need_decode<doDecode>::type DecodeJson(size_t & cursor, const String &
         return static_cast<typename need_decode<doDecode>::type>(raw_value.substr(base, size));
 }
 
-void SkipJson(size_t & cursor, const String & raw_value)
-{
-    DecodeJson<false>(cursor, raw_value);
-}
+void SkipJson(size_t & cursor, const String & raw_value) { DecodeJson<false>(cursor, raw_value); }
 
-String DecodeJsonAsBinary(size_t & cursor, const String & raw_value)
-{
-    return DecodeJson<true>(cursor, raw_value);
-}
+String DecodeJsonAsBinary(size_t & cursor, const String & raw_value) { return DecodeJson<true>(cursor, raw_value); }
 
-} // namespace DB
+} // namespace DB

dbms/src/Storages/Transaction/RegionBlockReader.cpp

@@ -55,7 +55,7 @@ static Field GenDecodeRow(const ColumnInfo & col_info)
         case TiDB::CodecFlagVarUInt:
             return Field(UInt64(0));
         case TiDB::CodecFlagJson:
-            return Field(String());
+            return TiDB::genJsonNull();
         case TiDB::CodecFlagDuration:
             return Field(Int64(0));
         default:

dbms/src/Storages/Transaction/TiDB.cpp

@@ -4,6 +4,12 @@
 #include <Storages/MutableSupport.h>
 #include <Storages/Transaction/TiDB.h>
 
+namespace DB
+{
+extern const UInt8 TYPE_CODE_LITERAL;
+extern const UInt8 LITERAL_NIL;
+} // namespace DB
+
 namespace TiDB
 {
 using DB::Decimal128;
@@ -49,6 +55,9 @@ Field ColumnInfo::defaultValueToField() const
         case TypeVarString:
         case TypeString:
             return value.convert<String>();
+        case TypeJSON:
+            // JSON can't have a default value
+            return genJsonNull();
         case TypeEnum:
             return getEnumIndex(value.convert<String>());
         case TypeNull:
@@ -282,8 +291,7 @@ catch (const Poco::Exception & e)
 
 TableInfo::TableInfo(const String & table_info_json) { deserialize(table_info_json); }
 
-String TableInfo::serialize() const
-try
+String TableInfo::serialize() const try
 {
     std::stringstream buf;
 
@@ -507,4 +515,11 @@ TableInfo TableInfo::producePartitionTableInfo(TableID table_or_partition_id) co
 
 String TableInfo::getPartitionTableName(TableID part_id) const { return name + "_" + std::to_string(part_id); }
 
+String genJsonNull()
+{
+    // null
+    const static String null({char(DB::TYPE_CODE_LITERAL), char(DB::LITERAL_NIL)});
+    return null;
+}
+
 } // namespace TiDB

dbms/src/Storages/Transaction/TiDB.h

@@ -43,12 +43,12 @@ using DB::Timestamp;
     M(Float, 4, Float, Float32, false)               \
     M(Double, 5, Float, Float64, false)              \
     M(Null, 6, Nil, Nothing, false)                  \
-    M(Timestamp, 7, UInt, MyDateTime, false)          \
+    M(Timestamp, 7, UInt, MyDateTime, false)         \
     M(LongLong, 8, Int, Int64, false)                \
     M(Int24, 9, VarInt, Int32, true)                 \
-    M(Date, 10, UInt, MyDate, false)                  \
+    M(Date, 10, UInt, MyDate, false)                 \
     M(Time, 11, Duration, Int64, false)              \
-    M(Datetime, 12, UInt, MyDateTime, false)          \
+    M(Datetime, 12, UInt, MyDateTime, false)         \
     M(Year, 13, Int, Int16, false)                   \
     M(NewDate, 14, Int, MyDate, false)               \
     M(Varchar, 15, CompactBytes, String, false)      \
@@ -288,4 +288,6 @@ struct TableInfo
 
 using DBInfoPtr = std::shared_ptr<DBInfo>;
 
+String genJsonNull();
+
 } // namespace TiDB

dbms/src/Storages/Transaction/TiKVDecodedValue.h

@@ -36,7 +36,7 @@ struct ValueExtraInfo
 
     void atomicUpdate(DecodedRow *& data) const
     {
-        static void * expected = nullptr;
+        void * expected = nullptr;
         if (!decoded.compare_exchange_strong(expected, (void *)data))
             delete data;
         data = nullptr;