Decimal migration fix for columnshard (#9625)

Author: azevaykin

ydb/core/scheme/scheme_types_proto.cpp

@@ -42,11 +42,15 @@ TTypeInfoMod TypeInfoModFromProtoColumnType(ui32 typeId, const NKikimrProto::TTy
         return res;
     }
     case NTypeIds::Decimal: {
-        Y_ABORT_UNLESS(typeInfo, "no type info for decimal type");
-        TTypeInfoMod res = {
-            .TypeInfo = {{typeInfo->GetDecimalPrecision(), typeInfo->GetDecimalScale()}},
-            .TypeMod = {}
-        };
+        ui32 precision, scale;
+        if (!typeInfo) {
+            precision = DECIMAL_PRECISION;
+            scale = DECIMAL_SCALE;
+        } else {
+            precision = typeInfo->GetDecimalPrecision();
+            scale = typeInfo->GetDecimalScale();
+        }
+        TTypeInfoMod res = {{TDecimalType(precision, scale)}, {}};
         return res;
     }
     default: {

ydb/core/tx/datashard/datashard_user_table.cpp

@@ -266,17 +266,8 @@ void TUserTable::ParseProto(const NKikimrSchemeOp::TTableDescription& descr)
     for (const auto& col : descr.GetColumns()) {
         TUserColumn& column = Columns[col.GetId()];
         if (column.Name.empty()) {
-            std::optional<NKikimrProto::TTypeInfo> typeInfo;
-            if (col.HasTypeInfo()) {
-                typeInfo = col.GetTypeInfo();
-            } else if (col.GetTypeId() == NScheme::NTypeIds::Decimal) {
-                // Migration from table with no decimal typeInfo
-                typeInfo = NKikimr::NScheme::DefaultDecimalProto();
-            } else {
-                typeInfo = {};
-            }
-
-            auto typeInfoMod = NScheme::TypeInfoModFromProtoColumnType(col.GetTypeId(), typeInfo ? &*typeInfo : nullptr);
+            auto typeInfoMod = NScheme::TypeInfoModFromProtoColumnType(col.GetTypeId(),
+                col.HasTypeInfo() ? &col.GetTypeInfo() : nullptr);
             column = TUserColumn(typeInfoMod.TypeInfo, typeInfoMod.TypeMod, col.GetName());
         }
         column.Family = col.GetFamily();