The coercions system allows us to add in lambdas as arguments
to Core and ORM elements without changing them at all.   By allowing
the lambda to produce a deterministic cache key where we can also
cheat and yank out literal parameters means we can move towards
having 90% of "baked" functionality in a clearer way right in
Core / ORM.

As a second step, we can have whole statements inside the lambda,
and can then add generation with __add__(), so then we have
100% of "baked" functionality with full support of ad-hoc
literal values.

Adds some more short_selects tests for the moment for comparison.

Other tweaks inside cache key generation as we're trying to
approach a certain level of performance such that we can
remove the use of "baked" from the loader strategies.

As we have not yet closed #4639, however the caching feature
has been fully integrated as of
b0cfa7379cf8513a821a3dbe3028c4965d9f85bd, we will also
add complete caching documentation here and close that issue
as well.

Closes: #4639
Fixes: #5380
Change-Id: If91f61527236fd4d7ae3cad1f24c38be921c90ba

This is based off of
I8091919d45421e3f53029b8660427f844fee0228 and includes
all documentation-only changes as a separate merge,
once the parent is merged.

Change-Id: I711adea23df0f9f0b1fe7c76210bd2de6d31842d

includes more replacements for create_engine(), Connection,
disambiguation of Result from future/baked

Change-Id: Icb60a79ee7a6c45ea9056c211ffd1be110da3b5e

Replaces a wide array of Sphinx-relative doc references
with an abbreviated absolute form now supported by
zzzeeksphinx.

Change-Id: I94bffcc3f37885ffdde6238767224296339698a2

zzzeeksphinx 1.1.2 in git can now convert short
prefix names in a configured lookup to fully qualified module
names, so that
we can have succinct and portable pyrefs
that still resolve absolutely.
It also includes a formatter that will format all pyrefs
in a fully consistent way regardless of the package path,
by unconditionally removing all package tokens but always
leaving class names in place including for methods, which
means we no longer have to deal with tildes in pyrefs.

The most immediate goal of the absolute prefixes is
that we have lots of
"ambiguous" names that appear in muliple places, like select(),
ARRAY, ENUM etc.   With the incoming future packages there
is going to be lots of name overlap so it is necessary
that all names eventually use absolute package paths
when Sphinx receives them.

In multiple stages, pyrefs will be converted using the
zzzeeksphinx tools/fix_xrefs.py tool so that doclinks can
be made absolute using symbolic prefixes.

For this review, the actual search and replace of symbols
is not performed, instead some general cleanup to prepare
the docs as well as a lookup file used by the tool
to do the conversion.   this relatively small patch will
be backported
with appropriate changes to 1.3, 1.2, 1.1 and the tool
can then be run on each branch individually.  We are shooting
for almost no warnings at all for master (still a handful
I can't figure out which don't seem to have any impact)
, very few for 1.3,
and for 1.2 / 1.1 we hope for a significant reduction
in warnings.

Overall for all versions pyrefs should
always point to the correct target, if they are in fact
hyperlinked.  it's better for a ref to go nowhere and
be plain text than go to the wrong thing.  Right now,
hundreds of API links are pointing to the wrong thing
as they are ambiguous names such as refresh(), insert(),
update(), select(), join(), JSON etc. and Sphinx sends these all
to essesntially random destinations among as many as five
or six possible choices per symbol.  A shorthand system
that allows us to use absolute refs without having
to type out a full blown absoulte module is the only
way this is going to work, and we should ultimately
seek to abandon any use of prefix dot for lookups.  Everything
should be on an underscore token so at the very least the module
spaces can be reorganized without having to search and replace
the entire documentation every time.

Change-Id: I484a7329034af275fcdb322b62b6255dfeea9151

This affects mostly docstrings, except in orm/events.py::dispose_collection()
where one parameter gets renamed: given that the method is
empty, it seemed reasonable to me to fix that too.

Closes: #4440
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/4440
Pull-request-sha: 779ed75acb6142e1f1daac467b5b14134529bb4b

Change-Id: Ic0553fe97853054b09c2453af76d96363de6eb0e

example suites, fixes #4132

Change-Id: Icf07f33fc99a880d6165d300579ef5d2c366f6f5

Added a new flag ``use_batch_mode`` to the psycopg2 dialect.  This flag
enables the use of psycopg2's ``psycopg2.extras.execute_batch``
extension when the :class:`.Engine` calls upon ``cursor.executemany()``.
This extension provides a critical performance increase by over an order of magnitude
when running INSERT statements in batch.  The flag is False by default
as it is considered to be experimental for now.

Change-Id: Ib88d28bc792958d47109f644ff1d08c897db4ff7
Fixes: #4109

Removed the warnings that are emitted when the LRU caches employed
by the mapper as well as loader srtategies reach their threshold; the
purpose of this warning was at first a guard against excess cache keys
being generated but became basically a check on the "creating many
engines" antipattern.   While this is still an antipattern, the presense
of test suites which both create an engine per test as well as raise
on all warnings will be an inconvenience; it should not be critical
that such test suites change their architecture just for this warning
(though engine-per-test suite is always better).

Change-Id: I41ef8cd642d05a845f53119b196440f9d7879cd9
Fixes: #4071