Question

I have an audit table in SQL server. It is to record an entry for each high-level user action, e.g. update a record, add a new record, delete a record etc.

I have a mechanism for detecting and recording all the changes made (in .NET, not as a trigger in the database) and have a collection of objects that record a field name, previous value and new value. I’m wanting to store the field changes in the same table (not in a separate table, i.e. I don’t want a full-blown normalised relational design for this), so I have a blob field (or it could be a character field) that I want to record the field-level audit data in.

I’m thinking I just want to take my object graph (basically just a list of these field change objects) and serialize it and store the serialized version in the table.

Later, when the user wants to view the changes I can deserialize the field and reconstruct the collection of field changes.

So, what would be the best framework/serialization format in .NET 3.5 to use? I don’t much mind about the size, and it doesn’t have to be human-readable.

Answer 1

Avoid BinaryFormatter for anything that you store long-term (for example in a database); because it contains type/assembly metadata you can easily find that you can’t deserialize the data later. Plus it is .NET-specific! So you’re a bit scuppered if you want to read it from any other platform.

JSON (via Json.NET) would make a simple, pretty readable format that doesn’t take much space. Xml via XmlSerializer or DataContractSerializer would be fine but isn’t as readable. If space is your biggest concern, perhaps something like “protocol buffers” (protobuf-net and others) – virtually impossible to read without the supporting utility dll, but very fast and efficient.

I’d be tempted to use JSON, personally. It means I can read the audit in SSMS…