We originally did the whole `load_database_yaml` thing because this test
wasn't cooperating and we needed to finish the namespaced rake tasks for
multiple databases.

However, it turns out that YAML can't eval ERB if you don't tell it it's
ERB so you get Pysch parse errors if you're using multi-line ERB or
ERB with conditionals. It's a hot mess.

After trying a few things and thinking it over we decided that it wasn't
worth bandaiding over, the test needed to be improved. The test was
added in #31135 to test that the env is loaded in these tasks. But it
was blowing up because we were trying to read a database name out of the
configuration - however that's not the purpose of this change. We want
to read environment files in the rake tasks, but not in the config
file.

In this PR we changed the test to test what the PR was actually fixing.
We've also deleted the `load_database_yaml` because it caused more
problems than it was worth. This should fix the issues described in
https://github.com/rails/rails/pull/32274#issuecomment-384161057. We
also had these problems at GitHub.
Co-authored-by: Nalimi <aibrahim2k2@gmail.com>

`changes_applied` should be called before continuing around callback
chain. Otherwise the mutation tracker returns old value for methods like
`changed`? or `id_in_database` in around callbacks. Also methods depend
on `id_in_database`, like `update_column`, are not working in
`around_create` callbacks.

```
class Foo < ActiveRecord::Base
  around_create :around_create_callback

  def around_create_callback
    ...
    yield
    p id_in_database # => nil
    update_column(:generated_column, generate_value) # silently fails
  end

  ...
end
```

* Add documentation for `:collation` option

The table definition supports a `:collation` option for string and text columns, but this is not documented anywhere that I could find.

I'm not sure if the "If not specified" part is accurate. From [this PR](https://github.com/rails/rails/commit/1515c4d98da3f730ef971fa5a13cad828bd9bef4), it looks like it passes `nil` and lets the database handle the collation, but I'm happy to change it if I misread the code.

[ci skip]

* FIX remove whitespace

[Nate Pinsky + Rafael Mendonça França]

This was introduced at 24f6bf0d.

https://github.com/rails/rails/issues/31190

The `Relation::Merger` has a problem that order values would be merged
as nested array.

That was caused an issue #33664 since if array value is passed to
`order` and first element in the array includes `?`, the array is
regarded as a prepared statement and bind variables.

https://api.rubyonrails.org/classes/ActiveRecord/Sanitization/ClassMethods.html#method-i-sanitize_sql_for_order

Just merging that as splat args like other values would fix the issue.

Fixes #33664.

Fixes #33520.

To prevent style check in review like https://github.com/rails/rails/pull/33608#discussion_r211087605.

- Move changelog entry of #33530 up in order to preserve the chronology
  since we always add new entries on the top of a changelog file.
- Clarify the changelog entry
- Clarify the docs of remove_foreign_key
- Ensure reversible of `remove_foreign_key` with `:primary_key` and `:to_table`
  options.

remove_foreign_key supports
- remove_foreign_key :accounts, :branches
- remove_foreign_key :accounts, to_table: :branches

but the second one is not reversible.

This branch is to fix and allow second one to be reversible.

[Nikolay Epifanov, Rich Chen]

If a transaction is opened and closed without any queries being run, we
can safely omit the `BEGIN` and `COMMIT` statements, as they only exist
to modify the connection's behaviour inside the transaction. This
removes the overhead of those statements when saving a record with no
changes, which makes workarounds like `save if changed?` unnecessary.

This implementation buffers transactions inside the transaction manager
and materializes them the next time the connection is used. For this to
work, the adapter needs to guard all connection use with a call to
`materialize_transactions`. Because of this, adapters must opt in to get
this new behaviour by implementing `supports_lazy_transactions?`.

If `raw_connection` is used to get a reference to the underlying
database connection, the behaviour is disabled and transactions are
opened eagerly, as we can't know how the connection will be used.
However when the connection is checked back into the pool, we can assume
that the application won't use the reference again and reenable lazy
transactions. This prevents a single `raw_connection` call from
disabling lazy transactions for the lifetime of the connection.

Related to #33520

The first thing this method does is run  on the argument. This change passes
in a string so we don't allocate a bunch of unnecessary extra strings by
calling to_s on a symbol over and over.

What?
From now on when `accepts_nested_attributes_for` defined and `extend` option
added the overwritten `build` method being called.

[Alireza Bashiri, Martins Polakovs]

This commit follows the path we started at commit #ea4f0e2b
and continued at PR #33229.

This reverts commit d162188d, reversing
changes made to 35767828.

Reason: #24131 conflicts the #5153's default order contract, it means
that existing apps would be broken by that change.

We don't want to break existing apps without a deprecation cycle.

Since 9ac7dd47, class level `update`, `destroy`, and `delete` were placed
in the `Persistence` module as class methods.

But `Relation#update` without passing ids which was introduced at #11898
is not a class method, and it was caused the extra scoping regression
#33470.

I moved the relation method back into the `Relation` to fix the
regression.

Fixes #33470.

To make it easier to construct boundable predicate.

The target object for counter cache is not always determined by the
primary key value on the model. I'd like to extract `update_couters`
onto the `Relation` for the internal use.

`5 =~ /\d/` returns nil, but Integer doesn't have a `match?` method.

In cases where the MatchData object is not used, this provides a speed-up:
https://github.com/JuanitoFatas/fast-ruby/#stringmatch-vs-stringmatch-vs-stringstart_withstringend_with-code-start-code-end

Clean up some concepts in the code while we're here.

* PostgreSQL 10 new relkind for partitioned tables

Starting with PostgreSQL 10, we can now have partitioned tables natively

* Add comment

* Remove extra space

* Add test for partition table in postgreSQL10

* Select 'p' for "BASE TABLE" and add a test case
to support PostgreSQL 10 partition tables

* Address RuboCop offense

* Addressed incorrect `postgresql_version`

Fixes #33008.

[Yannick Schutz & Yasuo Honda & Ryuta Kamizono]

Follow up of #33358 for SQLite3.

http links will be redirected to the https version, but still better to
just directly link to the https version.

Use attr_reader/attr_writer instead of methods

method is 12% slower

Use flat_map over map.flatten(1)

flatten is 66% slower

Use hash[]= instead of hash.merge! with single arguments

merge! is 166% slower

See https://github.com/rails/rails/pull/32337 for more conversation

The consecutive verbatim blocks were being merged making the output look weird.

The examples with `.where` uses hash w/ symbol keys so it would be more consistent to also do this with `.new`.
Also from my experience the hash w/ symbol keys is more widely used with `where/new/create` etc. in ActiveRecord.