[dinedal]

> I don't find that it becomes a mess at all, because properly crafted views and procedures strongly encourage forced indexing and checking execution plans when you refactor them; as opposed to in-code, ad-hoc queries where it's hard to know if someone ever ran tests to optimize them.

I have to provide caution here, when you create views and stored procedures, I've always found it a mess to maintain:

1) VCS for stored procedures and views is usually non existent. Good luck understanding how these change over time and who changed them.

2) Deploying application logic alongside these systems is very painful, because unless you've versioned your views/stored procedures, when you make a breaking change you need to stop the entire application, make the change in the DB, and restart the entire application again on the new version. Zero-downtime deploys would require versioned views/stored procedures.

3) It quickly becomes a challenge to answer the question "what happens when I do X?" reliably, where X is insert, delete, or even select a row. Once you have complex enough stored procedures, modifying the data changes things in unexpected or unintended ways. A dev unaware of how the system works might assume that inserting a row simply inserts a row, but instead due to stored procedures hidden from application logic, it might cascade into inserting rows elsewhere, deleting rows, or modifying other rows in other tables. Discovering these issues without knowing that they could exist is often done around midnight during a production outage, because a new feature was released that did something in the DB that was presumed safe, but wasn't. If the code for the business logic were in one place, the application, it would been much easier to see what the change would actually do.

I understand entirely that performance gains from good DB use are astronomical, but in my humble experience, I've found them to be more trouble in the long run than they are worth.

e: spelling

[taffer]

> VCS for stored procedures and views is usually non existent

This is a mindset problem, not a technology problem. Treat your stored procedures/functions/views like code, not like data. Keep a separate "code" schema, put your procedures/functions/views definitions in files, and store your files in Git, just like Java or Ruby code. Deployment then becomes an automated drop and recreate of the code schema in a single transaction with zero downtime.

> Deploying application logic alongside these systems is very painful

This is not my experience at all. The stored procedures form an API. If changing the API breaks your application, you are doing something fundamentally wrong. API versioning should only be necessary if third parties depend on your API, but I wouldn't recommend giving third parties direct access to the database anyway.

> Once you have complex enough stored procedures, modifying the data changes things in unexpected or unintended ways

I assume you mean triggers because stored procedures don't happen as side effects, you have to call them explicitly. Regarding triggers, I agree with everything you say.

[barnabee]

Re: VCS, I’ve found that with a small amount of setup, tools like Liquibase[0] allow you to maintain functions and views (with “CREATE OR REPLACE” or equivalent) as SQL files in a file system with full VCS, diffing, etc. just like any other code.

[0] https://www.liquibase.org/

[cropcirclbureau]

You still need to sequentially define your changes (migrations) which isn't exactly the VCS experience people are used to. If all changes to your db require new file entries, rarely do you need to diff let alone bisect to find out the history. It does make it harder to find out the current shape of your app though with all the ALTER statements to a single table strewn about multiple files. I wonder if it's feasible to write a tool that allows you to generate sequential migrations from DDL organized like tradition code with modules and items dealing with the same domain in the same file after diffing it with the sequential migrations already in the codebase.

[KptMarchewa]

Flyway solves 1.

As for 3, I would prefer to "go to" procedure rather than "come from".