I am currently working on a project in which I have to keep track of the tuples that are modified in a relational database. This should include updated tuples, but also inserted and deleted tuples. My question is what will be the best way to accomplish this? I have several ideas of my own, but maybe there are easier/better ways that I did not think of, or there already exists a project that exactly does this.
The final goal of the project is that it will work for relational databases of different vendors, but the first implementation will use a MySQL database. Other database systems can be supported later. But it would be nice if the solution that works for MySQL can be easily adapted to another database.
My first idea was to parse log files. However, I am not certain whether these logfiles contain the actual modified tuples, and furthermore I can imagine that these logfiles will not always be available (e.g. on shared hosting).
My second idea was to intercept the queries at the application level. When a INSERT, DELETE or UPDATE query is performed, these queries can be parsed, and the tuples that they will affect can be determined beforehand. For an INSERT operation this simply is the inserted tuple, and for a DELETE or UPDATE operation the tuples can be identified by applying the WHERE clause in a new SELECT statement.
As a last remark I want to add that performance is not an important factor at this stage of development.
If more details are needed I am happy to provide them.
Use triggers to capture the INSERT, UPDATE, and DELETE and log your entries to a new table. You can use a timestamp on that table to note when the transactions occurred. In the future you can query that table for your modification information.