If you are dealing with production-grade systems then yes, it is very bad. If it is your own pet project, then anything is allowed (if nothing else, it will be a learning experience 🙂 though chances are that sooner rather than later, even in a pet project, you will find yourself having put a cross … Read more
Suppose you have a single file in your repo, and you have the following commits: commit 1 : the file contains A commit 2 : the file contains B commit 3 : the file contains C If you execute revert on commit 3, you’ll have this in the repo: commit 1 : the file contains … Read more
It would not be a good idea to rollback sequences. Imagine two transactions happening at the same time, each of which uses the sequence for a unique id. If the second transaction commits and the first transaction rolls back, then the second inserted a row with “2” while the first rolls the sequence back to … Read more
Yes, everything that you do between the Begin Transaction and Commit (or Rollback) is part of the transaction.
You can use 13.6.7.2. DECLARE … HANDLER Syntax in the following way: DELIMITER $$ CREATE PROCEDURE `sp_fail`() BEGIN DECLARE `_rollback` BOOL DEFAULT 0; DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET `_rollback` = 1; START TRANSACTION; INSERT INTO `tablea` (`date`) VALUES (NOW()); INSERT INTO `tableb` (`date`) VALUES (NOW()); INSERT INTO `tablec` (`date`) VALUES (NOW()); — FAIL IF … Read more
These commands all come from Mercurial itself, and there are plenty of good compare/contrast posts for them. However, here they are in brief: rollback: one-level undo. Will undo the last pull or commit (can be dangerous) backout: create a new commit that is the inverse of a given commit. Net effect is an undo, but … Read more
The terms revert and amend have a well defined meaning in Git. In contrast, rollback and undo do not have such a well defined meaning, and are open to interpretation. Reverting a commit… …means creating (on the current branch) a new commit that applies the inverse changes that another commit introduced. It’s the preferred approach … Read more
Rolling back all migrations To rollback all migrations the best solution is the one @Claudio Floreani proposed: rake db:migrate VERSION=0 This will rollback every migration. You can read why this is the best approach in his answer. Then, run all migrations again with rake db:migrate Resetting the database Reset rake db:migrate:reset #runs db:drop db:create db:migrate … Read more
If you haven’t made a backup, you are pretty much fudged.
While Flyway supports rollbacks (as a commercial-only feature) its use is discouraged: https://flywaydb.org/documentation/command/undo While the idea of undo migrations is nice, unfortunately it sometimes breaks down in practice. As soon as you have destructive changes (drop, delete, truncate, …), you start getting into trouble. And even if you don’t, you end up creating home-made alternatives … Read more