See the CHANGELOG for details.

Fixes #950.

This reverts commit c99d507f.

- instance_variables return symbols in 1.9
- there is instance_variable_defined? method

fixes #3183

when fetching ids for a collection, bypass preloading
to avoid the unnecessary performance overhead

Allows two models to use the same table but have different primary keys.

load has_many associations keyed off a custom primary key if that key is present but the record is unsaved

Preserve SELECT columns on the COUNT for finder_sql when possible

If a record is removed from a has_many :through, all of the join records
relating to that record should also be removed from the through
association's target.

(Previously the records were removed in the database, but only one was
removed from the in-memory target array.)

Fixes #3425.

Fixes creating records in a through association with a polymorphic source
type.

Fix: habtm doesn't respect select query method

Closes #3104.

CollectionProxy#replace should change the DB records rather than just mutating the array. Fixes #3020.

Nested through associations: preloads from the default scope of a through model should not be included in the association scope. (We're already excluding includes.) Fixes #2834.

Ensure we are not comparing a string with a symbol in HasManyAssociation#inverse_updates_counter_cache?. Fixes #2755, where a counter cache could be decremented twice as far as it was supposed to be.

Disable active record marshalling tests on Ruby 1.8.7 on Travis CI, as they have been failing intermittently for a long while due to what appears to be a Ruby bug. If anyone has the skills/expertise/time to debug this, please speak to the Travis guys.

The join_nodes must be passed to the JoinDependency initializer and therefore counted by the alias tracker. This is because the association_joins are aliased on initialization and then the tables are cached, so it is no use to alias the join_nodes later. Fixes #2556.

We were experiencing CI test failures, for example:

* 3-1-stable: http://travis-ci.org/#!/rails/rails/builds/79473/L407
* master: http://travis-ci.org/#!/rails/rails/builds/79507/L80

These failures only happened on 1.8.7-p352, and we were only able to
reproduce on the Travis CI VM worker. We even tried creating a new 32
bit Ubuntu VM and running the tests on that, and it all worked fine.

After some epic trial and error, we discovered that replacing the
following:

  fuu = Marshal.load(Marshal.dump(fuu))

with:

  marshalled = Marshal.dump(fuu)
  fuu = Marshal.load(marshalled)

seemed to prevent the failure.

We have NO IDEA why this is. If anyone has some great insight to
contribute then that is welcome. Otherwise, hopefully this will just
help us get the CI green again.

Many thanks to @joshk for help with sorting this out.

Ensure that the foreign key gets set when doing record.create_association or record.create_association. Fixes #1960.