Adjusted the "from linter" warning feature to accommodate for a chain of
joins more than one level deep where the ON clauses don't explicitly match
up the targets, such as an expression such as "ON TRUE". This mode of use
is intended to cancel the cartesian product warning simply by the fact that
there's a JOIN from "a to b", which was not working for the case where the
chain of joins had more than one element.

this incurs a bit more compiler overhead that comes out in profiling
but is not extensive.

Added the "is_comparison" flag to the PostgreSQL "overlaps",
"contained_by", "contains" operators, so that they work in relevant ORM
contexts as well as in conjunction with the "from linter" feature.

Fixes: #6886
Change-Id: I078dc3fe6d4f7871ffe4ebac3e71e62f3f213d12

Change-Id: Ida86ed40c43d91813151621b847376976773a5f9

Fixed issue where a too-long constraint name rendered as part of the "ON
CONFLICT ON CONSTRAINT" element of the :class:`_postgresql.Insert`
construct due to naming convention generation would not correctly truncate
the name in the same way that it normally renders within a CREATE TABLE
statement, thus producing a non-matching and too-long constraint name.

Fixes: #6755
Change-Id: Ib27014a5ecbc9cd5861a396f8bb49fbc60bf49fe

Added new method :meth:`_sql.HasCTE.add_cte` to each of the
:func:`_sql.select`, :func:`_sql.insert`, :func:`_sql.update` and
:func:`_sql.delete` constructs. This method will add the given
:class:`_sql.CTE` as an "independent" CTE of the statement, meaning it
renders in the WITH clause above the statement unconditionally even if it
is not otherwise referenced in the primary statement. This is a popular use
case on the PostgreSQL database where a CTE is used for a DML statement
that runs against database rows independently of the primary statement.

Fixes: #6752
Change-Id: Ibf635763e40269cbd10f4c17e208850d8e8d0188

Fixed issue where the PostgreSQL ``ENUM`` datatype as embedded in the
``ARRAY`` datatype would fail to emit correctly in create/drop when the
``schema_translate_map`` feature were also in use. Additionally repairs a
related issue where the same ``schema_translate_map`` feature would not
work for the ``ENUM`` datatype in combination with a ``CAST``, that's also
intrinsic to how the ``ARRAY(ENUM)`` combination works on the PostgreSQL
dialect.

Fixes: #6739
Change-Id: I44b1ad4db4af3acbf639aa422c46c22dd3b0d3a6

Change-Id: I306cfbea9920b35100e3087dcc21d7ffa6c39c55

Fixed issue in :meth:`_postgresql.Insert.on_conflict_do_nothing` and
:meth:`_postgresql.Insert.on_conflict_do_update` where the name of a unique
constraint passed as the ``constraint`` parameter would not be properly
quoted if it contained characters which required quoting.

Fixes: #6696
Change-Id: I4ffca9b8c72cef4ed39e2de96831ccc11a620422