Ignored columns can only be dropped when its associated post-deploy
migration has been promoted to a regular migration. This is so because
Discourse doesn't rely on a schema file system to setup a brand new
database and thus the column information will be loaded by the
application first before the post-deploy migration runs.
We use schema_migration_details to determine the age of a site in multiple migrations. This commit moves the logic into a dedicated `Migration::Helpers` module so that it doesn't need to be re-implemented every time.
Our SafeMigrate system is designed to prevent tables/columns being dropped in pre-deploy migrations. Its regex-based detection was triggering incorrectly on `ALTER COLUMN DROP NOT NULL`.
This allows text editors to use correct syntax coloring for the heredoc sections.
Heredoc tag names we use:
languages: SQL, JS, RUBY, LUA, HTML, CSS, SCSS, SH, HBS, XML, YAML/YML, MF, ICS
other: MD, TEXT/TXT, RAW, EMAIL
Having a large number of post-deploy migrations running out-of-numerical-sequence with pre-deploy migrations can be problematic. For example, if we have the sequence
- db/migrate/2017... - add column
- db/post_migrate/2018... - drop the column
- db/migrate/2021... - add the same column again
It will work fine in numerical order. But if you run the pre-deploy migrations **followed by** the post-deploy migrations, you will not get the same result.
Our post-deploy system is designed to allow for seamless upgrades of Discourse. However, it is reasonable for us to only support this totally seamless experience for a limited period of time. This commit moves all post_deploy migrations which are more than 1 year old (i.e. more than 2 major Discourse versions ago) into the regular pre-deploy migrations directory. This limits the impact of any edge cases caused by out-of-numerical-sequence migrations.
Rails 6.1.3.1 deprecates a few API and has some internal changes that break our tests suite, so this commit fixes all the deprecations and errors and now Discourse should be fully compatible with Rails 6.1.3.1. We also have a new release of the rails_failover gem that's compatible with Rails 6.1.3.1.
We have the `# frozen_string_literal: true` comment on all our
files. This means all string literals are frozen. There is no need
to call #freeze on any literals.
For files with `# frozen_string_literal: true`
```
puts %w{a b}[0].frozen?
=> true
puts "hi".frozen?
=> true
puts "a #{1} b".frozen?
=> true
puts ("a " + "b").frozen?
=> false
puts (-("a " + "b")).frozen?
=> true
```
For more details see: https://samsaffron.com/archive/2018/02/16/reducing-string-duplication-in-ruby
This reverts commit 8b46f14744.
It corrects the reason for the revert:
We rely on SafeMigrate existing cause we call it from migrations,
Zeitwerk will autoload it.
Instead of previous pattern we explicitly bypass all the hacks in
production mode.
We need to disable SafeMigrate cause it is not thread safe.
A thread safe implementation is possible but not worth the effort,
we catch the issues in dev and test.
Temporarily recreate already dropped functions in the discourse_functions schema in order to allow restoring of backups which still reference dropped functions.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
`Upload#url` is more likely and can change from time to time. When it
does changes, we don't want to have to look through multiple tables to
ensure that the URLs are all up to date. Instead, we simply associate
uploads properly to `UserProfile` so that it does not have to replicate
the URLs in the table.
This moves us away from the delayed drops pattern which
was problematic on two counts. First, it uses a hardcoded "delay for"
duration which may be too short for certain deployment strategies.
Second, delayed drop doesn't ensure that it only runs after
the latest application code has been deployed. If the migration runs
and the application code fails to deploy, running the migration after
"delay for" has been met will cause the application to blow up.
The new strategy allows post deployment migrations to be skipped if the
env `SKIP_POST_DEPLOYMENT_MIGRATIONS` is provided.
```
SKIP_POST_DEPLOYMENT_MIGRATIONS=1 rake db:migrate
-> deploy app servers
SKIP_POST_DEPLOYMENT_MIGRATIONS=0 rake db:migrate
```
To aid with the generation of a post deployment migration, a generator
has been added. Simply run `rails generate post_migration`.
Introduce new patterns for direct sql that are safe and fast.
MiniSql is not prone to memory bloat that can happen with direct PG usage.
It also has an extremely fast materializer and very a convenient API
- DB.exec(sql, *params) => runs sql returns row count
- DB.query(sql, *params) => runs sql returns usable objects (not a hash)
- DB.query_hash(sql, *params) => runs sql returns an array of hashes
- DB.query_single(sql, *params) => runs sql and returns a flat one dimensional array
- DB.build(sql) => returns a sql builder
See more at: https://github.com/discourse/mini_sql
Often we need to amend our schema, it is tempting to use
drop_table, rename_column and drop_column to amned schema
trouble though is that existing code that is running in production
can depend on the existance of previous schema leading to application
breaking until new code base is deployed.
The commit enforces new rules to ensure we can never drop tables or
columns in migrations and instead use Migration::ColumnDropper and
Migration::TableDropper to defer drop the db objects
