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Rich Hickey's "Value of Values"[0] is what finally sold me on the benefits of pure functional programming and immutable data structures. (It remains horrifying

Rich Hickey's "Value of Values"[0] is what finally sold me on the benefits of pure functional programming and immutable data structures. (It remains horrifying to continue working with MySQL in my day job, knowing that every UPDATE is potentially a destructive action with no history and no undo.) [0]: https://www.youtube.com/watch?v=-6BsiVyC1kM https://www.youtube.com/watch?v=-6BsiVyC1kM

lbj 8y ago
Well put - I came here to say the same :)
juangacovas 8y ago
I thought the MySQL binlog was the history and mysqlbinlog the tool to help with the undo.
jamie_ca 8y ago
That feature's "coming" - part of SQL 2011 called System Versioning, currently supported in DB2 and SQL Server, but available in MariaDB 10.3 Beta according to this talk: https://youtu.be/xEDZQtAHpX8?t=2278 https://youtu.be/xEDZQtAHpX8?t=2278
spudlyo 8y ago
Often times MySQL is set up with auto-commit set to true, where every DML statement (like UPDATE) is wrapped in an implicit BEGIN and COMMIT. It doesn’t have to be that way though, you can manage the transaction yourself, and you don’t have to COMMIT if you don’t want to, you can undo (ROLLBACK) if necessary.
- lukifer 8y ago
  It’s true, transactions in MySQL work great. But once the change is committed, the previous value is overwritten permanently. If the user wants to undo five minutes later, or I want to audit based on the value a month ago, we’re hosed unless we’ve jumped backflips to bake versioning into the schema. I think Hickey’s comparison to git is apt: we don’t stand for that in version control for our code, why should we find that acceptable for user data?
  - vp8989 8y ago
    Because there is vastly more state in the world than there is code. And frankly, most state is not that important. Just wait until you work with a sufficiently large immutable system, they are an operational nightmare. You should opt-in to immutability when the state calculations are very complex and very expensive to get wrong. I do wish mainstream languages had better tools for safe, opt-in immutability. Something like a "Pure" attribute you assign to a function. It can only call other pure functions and the compiler can verify that it has no state changes in it's own code.

lbj 8y ago

Well put - I came here to say the same :)

juangacovas 8y ago

I thought the MySQL binlog was the history and mysqlbinlog the tool to help with the undo.

jamie_ca 8y ago

That feature's "coming" - part of SQL 2011 called System Versioning, currently supported in DB2 and SQL Server, but available in MariaDB 10.3 Beta according to this talk: https://youtu.be/xEDZQtAHpX8?t=2278 https://youtu.be/xEDZQtAHpX8?t=2278

spudlyo 8y ago

Often times MySQL is set up with auto-commit set to true, where every DML statement (like UPDATE) is wrapped in an implicit BEGIN and COMMIT. It doesn’t have to be that way though, you can manage the transaction yourself, and you don’t have to COMMIT if you don’t want to, you can undo (ROLLBACK) if necessary.

lukifer 8y ago
It’s true, transactions in MySQL work great. But once the change is committed, the previous value is overwritten permanently. If the user wants to undo five minutes later, or I want to audit based on the value a month ago, we’re hosed unless we’ve jumped backflips to bake versioning into the schema. I think Hickey’s comparison to git is apt: we don’t stand for that in version control for our code, why should we find that acceptable for user data?
- vp8989 8y ago
  Because there is vastly more state in the world than there is code. And frankly, most state is not that important. Just wait until you work with a sufficiently large immutable system, they are an operational nightmare. You should opt-in to immutability when the state calculations are very complex and very expensive to get wrong. I do wish mainstream languages had better tools for safe, opt-in immutability. Something like a "Pure" attribute you assign to a function. It can only call other pure functions and the compiler can verify that it has no state changes in it's own code.