Eagerly loaded collection and singular associations are ignored by the StatementCache, which causes errors when the queries they generate reference columns that were not eagerly loaded.

This commit skips the creation of the StatementCache as a fix for these scenarios.

Added a few more methods on Module/Class to the dangerous class methods
blacklist. (Technically, allocate and new are already protected currently because
we happen to redefine them in the current implantation.)

Closes #16792

[Joshua Cody & Yves Senn]

Closes #16757.

Prior to this patch schema loading rake tasks had the potential to leak a
connection to a different database. This had side-effects when rake tasks
operating on the current connection (like `db:seed`) were chained.

Since 'drop table if exists' statement does not always work with
some databases such as Oracle.

We're seeing too many failures to believe otherwise.

This reverts commits bc116a55,
cbde413d,
bf0a6793, and
2440933f.

Sets the connection collation to the database collation configured
in database.yml. Otherwise, `SET NAMES utf8mb4` will use the default
collation for that charset (utf8mb4_general_ci) when you may have chosen
a different collation, like utf8mb4_unicode_ci.

This only applies to literal string comparisons, not column values, so
it is unlikely to affect you.

so this assertion causes random test fail

Asserting that the message contains "QUERY PLAN" is enough for the adapter's test.
The plan may vary according to number of tuples etc. but that's out of our concern.

This reverts commit 16fe1983, reversing
changes made to 4c81c8ce.

The call to `Model.reset_column_information` was to express the intent of the test.
`reset_column_information` itself can trigger SQL queries because it checks
for a tables existance. Let's move it outside of the block.

/cc @sgrif

This test would fail when executed after any test that calls fixtures(:binaries)

There exists some other test files that load :minivans fixtures but don't load :speedometers.
Loading :speedometers here prevents the following error when this test was run after such test:
CalculationsTest#test_should_group_by_association_with_non_numeric_foreign_key:
ActiveRecord::RecordNotFound: Couldn't find all Speedometers with 'speedometer_id': (ABC, s1) (found 1 results, but was looking for 2)

Fixes #16701

* Also duplicated find_by tests from relations_test.rb to finder_test.rb now
	that we have a completely different implementation on the class (in core.rb
	with AST caching stuff).

* Also removed a (failing) test that used mocks. Now that we have tests for the
  behavior, there's no point having another test that tests the implementation
	(that it delegates). Further, what the test was implying is nolonger true with
	the current implementation, because Class.find_by is a real method now.

This is a reacon to https://github.com/rails/rails/commit/d6c1205584b1ba597db4071b168681678b1e9875#commitcomment-7502487
This backwards incompatibility was introduced with d6c12055 to fix #7516.
However both `connection.default_sequence_name` and `model.sequence_name` are public API.
The PostgreSQL adapter should honor the interface and return strings.

/cc @matthewd @chancancode

Fixes #16623 introduced by https://github.com/rails/rails/commit/3d5a2019bcccc6fb01bee4811ca669f4383edb51

with dynamic conditions.

Fixes #16128

This bug was introduced in https://github.com/rails/rails/commit/c35e438620f2d56562251571377995359546393d
so it's present from 4.1.2-rc1 and after.

https://github.com/rails/rails/commit/c35e438620f2d56562251571377995359546393d
merges any relation scopes passed as proc objects to the relation,
but does *not* take into account the arity of the lambda.

To reproduce: https://gist.github.com/Agis-/5f1f0d664d2cd08dfb9b

Fixes #15821.

Currently, Active Record will rescue any errors raised within
after_rollback/after_create callbacks and print them to the
logs. Next versions of rails will not rescue those errors anymore,
and just bubble them up, as the other callbacks.

This adds a opt-in flag to enable that behaviour, of not rescuing
the errors.
    Example:
      # For not swallow errors in after_commit/after_rollback
      config.active_record.errors_in_transactional_callbacks = true

[fixes #13460]

If the request parameters are passed to create_with and where they can
be used to do mass assignment when used in combination with
Relation#create.

Fixes CVE-2014-3514

Conflicts:
	activerecord/lib/active_record/relation/query_methods.rb

  Post.where(id: [[]]).to_a

Used to fail with a SQL syntax error (until 4.1):

  SELECT ... WHERE id in ();

It now properly generate:

  SELECT ... WHERE 1=0;