Change-Id: I14db8e9c69a832b0f5dae8036db3c0a70bb49edd

Fixed issue where :meth:`_engine.Result.freeze` method would not work for
textual SQL using either :func:`_sql.text` or
:meth:`_engine.Connection.exec_driver_sql`.

Fixes: #8963
Change-Id: Ia131c6ac41a4adf32eb1bf1abf23930ef395f16c
(cherry picked from commit 44170aee47a021883c6244f702de2e4385a5cd1d)

Removed non-functional method ``merge`` from :class:`_asyncio.AsyncResult`.
This method was non-functional and non-testes since the first introduction
of asyncio in SQLAlchemy.

Fixes: #7158
Fixes: #8952
Change-Id: Ibc3d17be8a8b7cab9bf2074f0408f74b4c4b161d
(cherry picked from commit ab8a21c613fb6c69b07f053e4622a4426b2e9ef0)

Fixed issue where the underlying DBAPI cursor would not be closed when
using :class:`_orm.Query` and direct iteration, if a user-defined exception
case were raised within the iteration process, interrupting the iterator
which otherwise is not possible to re-use in this context. When using
:meth:`_orm.Query.yield_per` to create server-side cursors, this would lead
to the usual MySQL-related issues with server side cursors out of sync.

To resolve, a catch for ``GeneratorExit`` is applied within the default
iterator, which applies only in those cases where the interpreter is
calling ``.close()`` on the iterator in any case.

A similar scenario can occur when using :term:`2.x` executions with direct
use of :class:`.Result`, in that case the end-user code has access to the
:class:`.Result` itself and should call :meth:`.Result.close` directly.
Version 2.0 will feature context-manager calling patterns to address this
use case.  However within the 1.4 scope, ensured that ``.close()`` methods
are available on all :class:`.Result` implementations including
:class:`.ScalarResult`, :class:`.MappingResult`.

Fixes: #8710
Change-Id: I3166328bfd3900957eb33cbf1061d0495c9df670

Change-Id: I5a241a70efba68bcea9819ddce6aebc25703e68d
(cherry picked from commit f8c4dba4e9f130c18ce00597c036bc26ae7abf90)

Implemented new :paramref:`_engine.Connection.execution_options.yield_per`
execution option for :class:`_engine.Connection` in Core, to mirror that of
the same :ref:`yield_per <orm_queryguide_yield_per>` option available in
the ORM. The option sets both the
:paramref:`_engine.Connection.execution_options.stream_results` option at
the same time as invoking :meth:`_engine.Result.yield_per`, to provide the
most common streaming result configuration which also mirrors that of the
ORM use case in its usage pattern.

Fixed bug in :class:`_engine.Result` where the usage of a buffered result
strategy would not be used if the dialect in use did not support an
explicit "server side cursor" setting, when using
:paramref:`_engine.Connection.execution_options.stream_results`. This is in
error as DBAPIs such as that of SQLite and Oracle already use a
non-buffered result fetching scheme, which still benefits from usage of
partial result fetching.   The "buffered" strategy is now used in all
cases where :paramref:`_engine.Connection.execution_options.stream_results`
is set.

Added :meth:`.FilterResult.yield_per` so that result implementations
such as :class:`.MappingResult`, :class:`.ScalarResult` and
:class:`.AsyncResult` have access to this method.

Fixes: #8199
Change-Id: I6dde3cbe483a1bf81e945561b60f4b7d1c434750
(cherry picked from commit e5a0cdb2eaa1d7f381e93d0529a7f8e6d5888877)

Change-Id: I0f8db2532827c76a2751186638d22104230db843
references: #8198
(cherry picked from commit 59bafe0fbefe16269c72ac39e699e4127d49841f)

A warning is emitted when calling upon the :meth:`.Result.columns` method
with only one index, in particular ORM related cases, indicating that the
current behavior of :meth:`.Result.columns` is broken in this case and
will be changed in 2.0.  To receive a collection of scalar values,
use the :meth:`.Result.scalars` method.

Fixes: #7953
Change-Id: I3c4ca3eecc2bfc85ad1c38000e5990d6dde80d22
(cherry picked from commit fe2045fb1c767436ed1e32359fe005dabead504a)

Fixed issue where the :meth:`_asyncio.AsyncSession.execute` method failed
to raise an informative exception if the ``stream_results`` execution
option were used, which is incompatible with a sync-style
:class:`_result.Result` object. An exception is now raised in this scenario
in the same way one is already raised when using ``stream_results`` in
conjunction with the :meth:`_asyncio.AsyncConnection.execute` method.
Additionally, for improved stability with state-sensitive dialects such as
asyncmy, the cursor is now closed when this error condition is raised;
previously with the asyncmy dialect, the connection would go into an
invalid state with unconsumed server side results remaining.

Fixes: #7667
Change-Id: I6eb7affe08584889b57423a90258295f8b7085dc
(cherry picked from commit faa9ef2cff53bde291df5ac3b5c4ed8f665ecd8c)