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What seems to be missing here is the DB tech he is using. On a proper database you can do your "undeleted" with triggers and it's relatively trivial. Nonsense

What seems to be missing here is the DB tech he is using. On a proper database you can do your "undeleted" with triggers and it's relatively trivial. Nonsense like a "deleted" column on your main data table just seems silly.

icedchai 4y ago
I worked at a place that kept all the deleted stuff in their main tables. It turned out over 90% of the rows were deleted. I'm not sure how often something was undeleted, but it was not very frequent. Some of these soft deleted rows were 5+ years old. Archive that crap.
- JohnBooty 4y ago
  Yeah, for sure, if deletion is going to be the exception rather than the rule.... keeping deleted stuff in the main tables is not ideal. Of course, you can have your cake and eat it too. You can e.g. keep your deleted crap in the main table (which makes certain things easier) and then hard-delete or archive it to another table after N days.
- dubswithus 4y ago
  I would never suggest archiving unless we're hitting some performance limit. Why generate more busy work? Just leave it there and if need be add more indexes and partitions.
  - icedchai 4y ago
    well, they were running into performance issues. This table had something like 100 columns and at least 30 indexes already. This table was fat. Many columns, many rows, mostly unused garbage. And several of these "columns" were actually JSON blobs that probably should've been in their own table. But what do I know. I left!
    - JohnBooty 4y ago
      When we talk about best practices, it's probably not too useful to talk about these sorts of "extremely high technical debt situations." Once you have an existing tirefire, it's a matter of damage control and "what is the least bad way to accomplish new functionality?" and the answer to that will always be unique for each unique tirefire.
robertlagrant 4y ago
Triggers don't solve what the author's getting at, i.e. who knows what else outside this database changes upon deletion that would need to be reversed? It's all in the article.
JohnBooty 4y ago
Nonsense like a "deleted" column on your main data table just seems silly. Why silly? Yeah, it's one more column, but most DBs just represent dates as bigints AFAIK so it's not really the end of the world. Sure, you have to be conscious of adding "where deleted_at = NULL" (or the opposite) to all your queries. If you're going through an ORM this is usually trivial e.g. in ActiveRecord it can be a default scope on your model. On a proper database you can do your "undeleted" with triggers and it's relatively trivial. I like this solution as well, FWIW. If I was retrofitting an existing application with soft-deletes I would definitely favor this solution. There are some obvious advantages over a "deleted" column on your main table for sure. One drawback is that you now have to keep two table definitions in sync. You also have to add conditional logic in a lot of places to handle whether a given piece of code is looking at a normal user from the "users" table or a deleted user from the "users_deleted" table. Instead of messing with the WHERE clause on every query, now you're messing with the table name on every query. So that's a wash IMO.

icedchai 4y ago

I worked at a place that kept all the deleted stuff in their main tables. It turned out over 90% of the rows were deleted. I'm not sure how often something was undeleted, but it was not very frequent. Some of these soft deleted rows were 5+ years old. Archive that crap.

JohnBooty 4y ago
Yeah, for sure, if deletion is going to be the exception rather than the rule.... keeping deleted stuff in the main tables is not ideal. Of course, you can have your cake and eat it too. You can e.g. keep your deleted crap in the main table (which makes certain things easier) and then hard-delete or archive it to another table after N days.
dubswithus 4y ago
I would never suggest archiving unless we're hitting some performance limit. Why generate more busy work? Just leave it there and if need be add more indexes and partitions.
- icedchai 4y ago
  well, they were running into performance issues. This table had something like 100 columns and at least 30 indexes already. This table was fat. Many columns, many rows, mostly unused garbage. And several of these "columns" were actually JSON blobs that probably should've been in their own table. But what do I know. I left!
  - JohnBooty 4y ago
    When we talk about best practices, it's probably not too useful to talk about these sorts of "extremely high technical debt situations." Once you have an existing tirefire, it's a matter of damage control and "what is the least bad way to accomplish new functionality?" and the answer to that will always be unique for each unique tirefire.

robertlagrant 4y ago

Triggers don't solve what the author's getting at, i.e. who knows what else outside this database changes upon deletion that would need to be reversed? It's all in the article.

JohnBooty 4y ago

Nonsense like a "deleted" column on your main data table just seems silly. Why silly? Yeah, it's one more column, but most DBs just represent dates as bigints AFAIK so it's not really the end of the world. Sure, you have to be conscious of adding "where deleted_at = NULL" (or the opposite) to all your queries. If you're going through an ORM this is usually trivial e.g. in ActiveRecord it can be a default scope on your model. On a proper database you can do your "undeleted" with triggers and it's relatively trivial. I like this solution as well, FWIW. If I was retrofitting an existing application with soft-deletes I would definitely favor this solution. There are some obvious advantages over a "deleted" column on your main table for sure. One drawback is that you now have to keep two table definitions in sync. You also have to add conditional logic in a lot of places to handle whether a given piece of code is looking at a normal user from the "users" table or a deleted user from the "users_deleted" table. Instead of messing with the WHERE clause on every query, now you're messing with the table name on every query. So that's a wash IMO.