Changed the query style for ORM queries emitted by :meth:`.Session.get` as
well as many-to-one lazy load queries to use the default labeling style,
:attr:`_sql.SelectLabelStyle.LABEL_STYLE_DISAMBIGUATE_ONLY`, which normally
does not apply labels to columns in a SELECT statement. Previously, the
older style :attr:`_sql.SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL`
that labels columns as `<tablename>_<columname>` was used for
:meth:`.Session.get` to maintain compatibility with :class:`_orm.Query`.
The change allows the string representation of ORM queries to be less
verbose in all cases outside of legacy :class:`_orm.Query` use. Pull
request courtesy Inada Naoki.
Fixes: #12932Closes: #12926
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/12926
Pull-request-sha: 6738a73f63
Change-Id: I044a54226a4fcade07adc1a3f5f60b4b3e451a1e
Repaired a major shortcoming which was identified in the
:ref:`engine_insertmanyvalues` performance optimization feature first
introduced in the 2.0 series. This was a continuation of the change in
2.0.9 which disabled the SQL Server version of the feature due to a
reliance in the ORM on apparent row ordering that is not guaranteed to take
place. The fix applies new logic to all "insertmanyvalues" operations,
which takes effect when a new parameter
:paramref:`_dml.Insert.returning.sort_by_parameter_order` on the
:meth:`_dml.Insert.returning` or :meth:`_dml.UpdateBase.return_defaults`
methods, that through a combination of alternate SQL forms, direct
correspondence of client side parameters, and in some cases downgrading to
running row-at-a-time, will apply sorting to each batch of returned rows
using correspondence to primary key or other unique values in each row
which can be correlated to the input data.
Performance impact is expected to be minimal as nearly all common primary
key scenarios are suitable for parameter-ordered batching to be
achieved for all backends other than SQLite, while "row-at-a-time"
mode operates with a bare minimum of Python overhead compared to the very
heavyweight approaches used in the 1.x series. For SQLite, there is no
difference in performance when "row-at-a-time" mode is used.
It's anticipated that with an efficient "row-at-a-time" INSERT with
RETURNING batching capability, the "insertmanyvalues" feature can be later
be more easily generalized to third party backends that include RETURNING
support but not necessarily easy ways to guarantee a correspondence
with parameter order.
Fixes: #9618
References: #9603
Change-Id: I1d79353f5f19638f752936ba1c35e4dc235a8b7c
updates for Insert / bulk insert, executemanyvalues,
as well as beginning to describe Table / declared class more
closely together, mentioning typing support.
Fixed a long-standing issue where sphinx would complain about
the Insert symbol being ambiguous.
Change-Id: Id4cc09b9581e8fa39c9c00bc8f229636e626e9bc
Added script to format code in the rst documentation using black.
This is also added to the lint tox job to ensure that the code
in the docs is properly formatted.
Change-Id: I799444f22da153484ca5f095d57755762348da40
reviewers: these docs publish periodically at:
https://docs.sqlalchemy.org/en/gerrit/4042/orm/queryguide/index.html
See the "last generated" timestamp near the bottom of the
page to ensure the latest version is up
Change includes some other adjustments:
* small typing fixes for end-user benefit
* removal of a bunch of old examples for patterns that nobody
uses or aren't really what we promote now
* modernization of some examples, including inheritance
Change-Id: I9929daab7797be9515f71c888b28af1209e789ff
the feature is enabled for all built in backends
when RETURNING is used,
except for Oracle that doesn't need it, and on
psycopg2 and mssql+pyodbc it is used for all INSERT statements,
not just those that use RETURNING.
third party dialects would need to opt in to the new feature
by setting use_insertmanyvalues to True.
Also adds dialect-level guards against using returning
with executemany where we dont have an implementation to
suit it. execute single w/ returning still defers to the
server without us checking.
Fixes: #6047Fixes: #7907
Change-Id: I3936d3c00003f02e322f2e43fb949d0e6e568304
the session commit/close docs still feel awkward in how
one learns about this operation. hopefully another pass
over 2.0 can make things more linear.
removed a 1.4 note about autobegin that was completely inaccurate;
commit() does autobegin so it has an effect, just not usually
on the database.
Change-Id: Iaa4b96bd3df6cf82e851b2943322ddad7abbbac0
Add SelectBase.exists() method as it seems strange this is
not available already. The Exists construct itself does
not provide full SELECT-building capabilities so it makes
sense this should be used more like a scalar_subquery.
Make sure stream_results is getting set up when yield_per
is used, for 2.0 style statements as well. this was
hardcoded inside of Query.yield_per() and is now moved
to take place within QueryContext.
Change-Id: Icafcd4fd9b708772343d56edf40995c9e8f835d6
Inada Naoki