ActiveRecord::Relation::Merger's filter_binds method does not filter out bind
variables when one of the attribute nodes has a string name, but the other has
a symbol name, even when those names are actually equal.

This can result in there being more bind variables than placeholders in the
generated SQL.  This is particularly an issue for PostgreSQL, where this is
treated as an error.

This patch changes the filter_binds method to make it convert both attribute
names to strings before comparing.

Closes #10802.

Before this patch `Infinity`, `-Infinity` and `Nan` were read as `0`.

In #10410 it was noted that you can no longer create PK's with the
type of bigserial in PostgreSQL in 4.0.0.rc1. This is mostly
because the newer adapter is checking for column type with the
id column instead of just letting it pass through like it did
before.

Side effects:
You may just create a PK column of a type that you really don't
want to be your PK. As far as I can tell this was allowed in 3.2.X
and perhaps an exception should be raised if you try and do
something extremely dumb.

by each database bind variable naming conventions

Closes #15024.

These operations happen before instances are created.
The current behavior is misleading and can result in broken behavior.

We are reverting these commits, because there are other caveats related
to dirty attributes not being restored when a transaction is rollback.
For instance, nested transactions cannot proper restore the dirty
attributes state after a rollback.

At the moment, the dirty attributes are scoped by the transaction.
When we call `.save` on a record, the dirty attributes will be reset even
if the transaction gets rollback.

[related #13166]
[related #15018]
[related #15016]
[closes #15019]

This reverts commits
* bab48f0a
  * b0fa7cf3.
* 73fb39b6
  * 37c23892.
  * 8d8d4f15

Revert "Merge pull request #13166 from bogdan/transaction-magic"

I wanted the middle model to be anonymous, but we have to give it a name
for marshal support. :'(

This test was inspired by #14866. That PR would break this
functionality and we should make sure we notice that in the future.

This resulted in some unrelated errors on Traivs:

  1) Error:
PostgresqlUUIDTest#test_treat_blank_uuid_as_nil:
ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR:  column "thingy" of relation "uuid_data_type" does not exist
LINE 1: INSERT INTO "uuid_data_type" ("thingy") VALUES ($1) RETURNIN...
                                      ^
: INSERT INTO "uuid_data_type" ("thingy") VALUES ($1) RETURNING "id"

/cc @zuhao

HABTM should fall back to using the normal CollectionAssociation's size calculation if the collection is not cached or loaded.

This addresses both #14913 and #14914 for master.

[related #13166]

This case prevents against regressions. The change was suggested in a recent
PR but the all our tests passed.

This makes table_name_suffix work the same as table_name_prefix when
using namespaced models. Pretty much the same as 67d1cec4.

This is a regression 4.0 -> 4.1 fix.
In 4.1.0 Relation#join is delegated to Arel#SelectManager.
In 4.0 series it is delegated to Array#join

This patch puts back the behaviour of 4.0

Only care about its truthiness rather than asserting specific true/false
values. If we need to check for the return value in particular, there will
be a test for that.

Also change other related test to use existing record rather than
creating new one.

bind parameters we not being propogated to simple subquery calculation
calls. This fixes it

associations were not being saved.

Fixes #13854.

[Eric Chahin, Aaron Nelson, & Kevin Casey]

For mysql2/mysql adapters, `sql_mode` variable name set in `database.yml`
as string, was ignored and `sql_mode` was set to use strict mode.

Fixes #14895

Test checks that SQL is the same for a loaded vs not loaded
association (category.categorizations, category.categorization.delete_all
vs category.cartegroization.delete_al). This was fixed for delete_all
dependency but was not fixed for no (:nullify, or nil) dependency).

Since clear shouldn't fire callbacks the order doesn't
matter since it was never updated. Remove the portion
of this test that tests for order after clear.

Clear should not call callbacks because it clear calls
delete_all and then returns self. It should behave the same
as delete_all. This test clarifies the goal of the test and
tests the correct outcome.

When used a custom join_table name on a habtm, rails was not saving it
on Reflections. This causes a problem when rails loads fixtures, because
it uses the reflections to set database with fixtures.

Conflicts:
	activerecord/test/cases/validations/association_validation_test.rb

Causes a double // in Dir.glob that breaks Ruby 2.2-trunk.
Not really a bug, but not relevant to this test either.

Originally added in ed21f0c5

Closes #14841.

This file is using this pattern already

Fixes #14752

Select mimics the block interface of arrays, but does not mock the
block interface for select!. This change moves the api to be a
private method, _select!.