- The "hashable" flag on special datatypes such as :class:`.postgresql.ARRAY`,
:class:`.postgresql.JSON` and :class:`.postgresql.HSTORE` is now
set to False, which allows these types to be fetchable in ORM
queries that include entities within the row.  fixes #3499
- The Postgresql :class:`.postgresql.ARRAY` type now supports multidimensional
indexed access, e.g. expressions such as ``somecol[5][6]`` without
any need for explicit casts or type coercions, provided
that the :paramref:`.postgresql.ARRAY.dimensions` parameter is set to the
desired number of dimensions. fixes #3487
- The return type for the :class:`.postgresql.JSON` and :class:`.postgresql.JSONB`
when using indexed access has been fixed to work like Postgresql itself,
and returns an expression that itself is of type :class:`.postgresql.JSON`
or :class:`.postgresql.JSONB`.  Previously, the accessor would return
:class:`.NullType` which disallowed subsequent JSON-like operators to be
used. part of fixes #3503
- The :class:`.postgresql.JSON`, :class:`.postgresql.JSONB` and
:class:`.postgresql.HSTORE` datatypes now allow full control over the
return type from an indexed textual access operation, either ``column[someindex].astext``
for a JSON type or ``column[someindex]`` for an HSTORE type,
via the :paramref:`.postgresql.JSON.astext_type` and
:paramref:`.postgresql.HSTORE.text_type` parameters. also part of fixes #3503
- The :attr:`.postgresql.JSON.Comparator.astext` modifier no longer
calls upon :meth:`.ColumnElement.cast` implicitly, as PG's JSON/JSONB
types allow cross-casting between each other as well.  Code that
makes use of :meth:`.ColumnElement.cast` on JSON indexed access,
e.g. ``col[someindex].cast(Integer)``, will need to be changed
to call :attr:`.postgresql.JSON.Comparator.astext` explicitly.  This is
part of the refactor in references #3503 for consistency in operator
use.

didn't implement ``__slots__``, and therefore meant all subclasses
of that class didn't either, negating the rationale for ``__slots__``
to be in use.  Didn't cause any issue except on IronPython
which apparently does not implement ``__slots__`` behavior compatibly
with cPython.
Fixes #3494

that a Python descriptor is no longer used; repairs inspectability
of these methods including support for Sphinx documentation.

rows failed to implement ``__slots__`` correctly such that it still
had a ``__dict__``.    This is resolved, but in the extremely
unlikely case someone was assigning values to the returned tuples,
that will no longer work.
fixes #3420

primaryjoin of a relationship involved comparison to an unhashable
type such as an HSTORE, lazy loads would fail due to a hash-oriented
check on the statement parameters, modified in 1.0 as a result of
:ticket:`3061` to use hashing and modified in :ticket:`3368`
to occur in cases more common than "load on pending".
The values are now checked for the ``__hash__`` attribute beforehand.
fixes #3416

This makes unique_list approx 2x faster in my (simple) tests

has been liberalized to warn for values that aren't even string
values, such as integers; previously, the updated warning system
of 1.0 made use of string formatting operations which
would raise an internal TypeError.   While these cases should ideally
raise totally, some backends like SQLite and MySQL do accept them
and are potentially in use by legacy code, not to mention that they
will always pass through if unicode conversion is turned off
for the target backend.
fixes #3346