Ensure TypeDecorator delegates _set_parent_with_dispatch as well as
_set_parent to itself as well as its impl, as the TypeDecorator
class itself may have an active SchemaType implementation as well.

Fixed regression which occurred as a side effect of :ticket:`2919`,
which in the less typical case of a user-defined
:class:`.TypeDecorator` that was also itself an instance of
:class:`.SchemaType` (rather than the implementation being such)
would cause the column attachment events to be skipped for the
type itself.

Change-Id: I0afb498fd91ab7d948e4439e7323a89eafcce0bc
Fixes: #3832

The Boolean and Enum types both place SchemaType second in the
inheritance hierarchy.  In the case of Enum, this works
out that the copy() method is called from the base TypeEngine
which fails to transfer _create_events.   The test suite
doesn't seem to work with the inhertance hierarchy set up like
this as the event listeners don't work out, the _on_metadata_create
and _on_table_create hooks cause the production of an adapted type
which then adds event listeners that cause deque changed while
iteration.  It's not clear why Enum /Boolean don't have this problem.
But in any case it seems like the class mechanics for these types
remains fragile and would benefit from yet another refactor someday.

Change-Id: Ib641a5d2321b00f58bbe98dd0c5e789374db32b2
Fixes: #3827

The change in Index for 1.1 combined with the fix for
ref #3763 still fails to deliver the correct object
resolved by __clause_element__() to the list of expressions
for compilation.   Make sure we use the expression that's
been unwrapped from __clause_element__().

Change-Id: Ie1df8db5090de665048331786f0024d52851923f
Fixes: #3763

Fixed bug where :class:`.Index` would fail to extract columns from
compound SQL expressions if those SQL expressions were wrapped inside
of an ORM-style ``__clause_element__()`` construct.  This bug
exists in 1.0.x as well, however in 1.1 is more noticeable as
hybrid_property @expression now returns a wrapped element.

Fixes: #3763

Change-Id: I992536386503a1fb3f2305790abe008d72c44c4a

and test/sql/test_metadata IndexTest into
test/sql/test_metadata ConstraintTest

Change-Id: I7aeee9a1edbbd889200afc393695f73d5fbac3f3

Fixed bug in :class:`.Table` where the internal method
``_reset_exported()`` would corrupt the state of the object.  This
method is intended for selectable objects and is called by the ORM
in some cases; an erroneous mapper configuration would could lead the
ORM to call this on on a :class:`.Table` object.

Change-Id: I63fa34ee0cdf16358bb125c556390df79758bcbc
Fixes: #3755

count() here is misleading in that it not only
counts from an arbitrary column in the table, it also
does not make accommodations for DISTINCT, JOIN, etc.
as the ORM-level function does.  Core should not be
attempting to provide a function like this.

Change-Id: I9916fc51ef744389a92c54660ab08e9695b8afc2
Fixes: #3724

Fixes an issue where a Column would be copied with unique=True
and at the same time the UniqueConstraint would also be copied,
leading to duplicate UniqueConstraints in the target table,
when tometadata() is used.   Imitates the same logic used
by index=True/Index to avoid duplicates.  For some reason
a fix was implemented for Index long ago but never for
UniqueConstraint.

Change-Id: Ie622ee912a6fb8bf0ea900a8b09d78c7ebc79fc0
Fixes: #3721

Previously, it was impossible to have a Table that has
None for a schema name when the "schema" parameter on
MetaData was set.  A new symbol sqlalchemy.schema.BLANK_SCHEMA
is added which indicates that the schema name should unconditionally
be set to None.  In particular, this value must be passed within
cross-schema foreign key reflection, so that a Table which
is in the "default" schema can be represented properly.

Fixes: #3716
Change-Id: I3d24f99c22cded206c5379fd32a225e74edb7a8e

need this collection except in the extend/update uses where we
create it ad-hoc.  simplifies pickling.  Compatibility with 1.0
should be OK as ColumnColleciton uses __getstate__ in any case
and the __setstate__ contract hasn't changed.
- Fixed bug in :class:`.Table` metadata construct which appeared
around the 0.9 series where adding columns to a :class:`.Table`
that was unpickled would fail to correctly establish the
:class:`.Column` within the 'c' collection, leading to issues in
areas such as ORM configuration.   This could impact use cases such
as ``extend_existing`` and others.  fixes #3632