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* Add a third labeling mode for SELECT statementsMike Bayer2020-03-291-38/+152
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Enhanced the disambiguating labels feature of the :func:`~.sql.expression.select` construct such that when a select statement is used in a subquery, repeated column names from different tables are now automatically labeled with a unique label name, without the need to use the full "apply_labels()" feature that conbines tablename plus column name. The disambigated labels are available as plain string keys in the .c collection of the subquery, and most importantly the feature allows an ORM :func:`.orm.aliased` construct against the combination of an entity and an arbitrary subquery to work correctly, targeting the correct columns despite same-named columns in the source tables, without the need for an "apply labels" warning. The existing labeling style is now called LABEL_STYLE_TABLENAME_PLUS_COL. This labeling style will remain used throughout the ORM as has been the case for over a decade, however, the new disambiguation scheme could theoretically replace this scheme entirely. The new scheme would dramatically alter how SQL looks when rendered from the ORM to be more succinct but arguably harder to read. The tablename_columnname scheme used by Join.c is unaffected here, as that's still hardcoded to that scheme. Fixes: #5221 Change-Id: Ib47d9e0f35046b3afc77bef6e65709b93d0c3026
* Correct ambiguous func / class linksMike Bayer2020-03-251-32/+32
| | | | | | | | | :func:`.sql.expression.select`, :func:`.sql.expression.insert` and :class:`.sql.expression.Insert` were hitting many ambiguous symbol errors, due to future.select, as well as the PG/MySQL variants of Insert. Change-Id: Iac862bfc172a7f7f0cbba5353a83dc203bed376c
* Merge "Implement SQL VALUES in core."mike bayer2020-03-241-0/+122
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| * Implement SQL VALUES in core.Gord Thompson2020-03-241-0/+122
| | | | | | | | | | | | | | | | | | | | | | | | | | Added a core :class:`Values` object that enables a VALUES construct to be used in the FROM clause of an SQL statement for databases that support it (mainly PostgreSQL and SQL Server). Fixes: #4868 Closes: #5030 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5030 Pull-request-sha: 84684038a8efa93b460318e0db53f6c644554588 Change-Id: Ib8109b63bc1a9dc04ab987c5322ca3375f7e824d
* | Merge "Convert schema_translate to a post compile"mike bayer2020-03-241-2/+1
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| * Convert schema_translate to a post compileMike Bayer2020-03-241-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Revised the :paramref:`.Connection.execution_options.schema_translate_map` feature such that the processing of the SQL statement to receive a specific schema name occurs within the execution phase of the statement, rather than at the compile phase. This is to support the statement being efficiently cached. Previously, the current schema being rendered into the statement for a particular run would be considered as part of the cache key itself, meaning that for a run against hundreds of schemas, there would be hundreds of cache keys, rendering the cache much less performant. The new behavior is that the rendering is done in a similar manner as the "post compile" rendering added in 1.4 as part of :ticket:`4645`, :ticket:`4808`. Fixes: #5004 Change-Id: Ia5c89eb27cc8dc2c5b8e76d6c07c46290a7901b6
* | Remove deprecated elements from selectable.py; remove lockmodeMike Bayer2020-03-231-33/+1
|/ | | | | | | | | | | | | Removed autocommit and legacy "for update" / "lockmode" elements from selectable.py / query.py. lockmode was removed from selectable in 693938dd6fb2f3ee3e031aed4c62355ac97f3ceb however was not removed from the ORM. Also removes the ignore_nonexistent_tables option on join(). Change-Id: I0cfcf9e6a8d4ef6432c9e25ef75173b3b3f5fd87 Partially-fixes: #4643
* Merge "Rework select(), CompoundSelect() in terms of CompileState"mike bayer2020-03-111-432/+274
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| * Rework select(), CompoundSelect() in terms of CompileStateMike Bayer2020-03-101-432/+274
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Continuation of I408e0b8be91fddd77cf279da97f55020871f75a9 - add an options() method to the base Generative construct. this will be where ORM options can go - Change Null, False_, True_ to be singletons, so that we aren't instantiating them and having to use isinstance. The previous issue with this was that they would produce dupe labels in SELECT statements. Apply the duplicate column logic, newly added in 1.4, to these objects as well as to non-apply-labels SELECT statements in general as a means of improving this. - create a revised system for generating ClauseList compilation constructs that simplfies up front creation to not actually use ClauseList; a simple tuple is rendered by the compiler using the same constrcution rules as what are used for ClauseList but without creating the actual object. Apply to Select, CompoundSelect, revise Update, Delete - Select, CompoundSelect get an initial CompileState implementation. All methods used only within compilation are moved here - refine update/insert/delete compile state to not require an outside boolean - refine and simplify Select._copy_internals - rework bind(), which is going away, to not use some of the internal traversal stuff - remove "autocommit", "for_update" parameters from Select, references #4643 - remove "autocommit" parameter from TextClause , references #4643 - add deprecation warnings for statement.execute(), engine.execute(), statement.scalar(), engine.scalar(). Fixes: #5193 Change-Id: I04ca0152b046fd42c5054ba10f37e43fc6e5a57b
* | Simplified module pre-loading strategy and made it linter friendlyFederico Caselli2020-03-071-30/+29
|/ | | | | | | | | | | | | | | | | Introduced a modules registry to register modules that should be lazily loaded in the package init. This ensures that they are in the system module cache, avoiding potential thread safety issues as when importing them directly in the function that uses them. The module registry is used to obtain these modules directly, ensuring that the all the lazily loaded modules are resolved at the proper time This replaces dependency_for decorator and the dependencies decorator logic, removing the need to pass the resolved modules as arguments of the decodated functions and removes possible errors caused by linters. Fixes: #4689 Fixes: #4656 Change-Id: I2e291eba4297867fc0ddb5d875b9f7af34751d01
* Decouple compiler state from DML objects; make cacheableMike Bayer2020-03-061-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Targeting select / insert / update / delete, the goal is to minimize overhead of construction and generative methods so that only the raw arguments passed are handled. An interim stage that converts the raw state into more compiler-ready state is added, which is analogous to the ORM QueryContext which will also be rolled in to be a similar concept, as is currently being prototyped in I19e05b3424b07114cce6c439b05198ac47f7ac10. the ORM update/delete BulkUD concept is also going to be rolled onto this idea. So while the compiler-ready state object, here called DMLState, looks a little thin, it's the base of a bigger pattern that will allow for ORM functionality to embed itself directly into the compiler, execution context, and result set objects. This change targets the DML objects, primarily focused on the values() method which is the most complex process. The work done by values() is minimized as much as possible while still being able to create a cache key. Additional computation is then offloaded to a new object ValuesState that is handled by the compiler. Architecturally, a big change here is that insert.values() and update.values() will generate BindParameter objects for the values now, which are then carefully received by crud.py so that they generate the expected names. This is so that the values() portion of these constructs is cacheable. for the "multi-values" version of Insert, this is all skipped and the plan right now is that a multi-values insert is not worth caching (can always be revisited). Using the coercions system in values() also gets us nicer validation for free, we can remove the NotAClauseElement thing from schema, and we also now require scalar_subquery() is called for an insert/update that uses a SELECT as a column value, 1.x deprecation path is added. The traversal system is then applied to the DML objects including tests so that they have traversal, cloning, and cache key support. cloning is not a use case for DML however having it present allows better validation of the structure within the tests. Special per-dialect DML is explicitly not cacheable at the moment, more as a proof of concept that third party DML constructs can exist as gracefully not-cacheable rather than producing an incomplete cache key. A few selected performance improvements have been added as well, simplifying the immutabledict.union() method and adding a new SQLCompiler function that can generate delimeter-separated clauses like WHERE and ORDER BY without having to build a ClauseList object at all. The use of ClauseList will be removed from Select in an upcoming commit. Overall, ClaustList is unnecessary for internal use and only adds overhead to statement construction and will likely be removed as much as possible except for explcit use of conjunctions like and_() and or_(). Change-Id: I408e0b8be91fddd77cf279da97f55020871f75a9
* Ensure all nested exception throws have a causeMike Bayer2020-03-021-8/+14
| | | | | | | | | | | | | | | Applied an explicit "cause" to most if not all internally raised exceptions that are raised from within an internal exception catch, to avoid misleading stacktraces that suggest an error within the handling of an exception. While it would be preferable to suppress the internally caught exception in the way that the ``__suppress_context__`` attribute would, there does not as yet seem to be a way to do this without suppressing an enclosing user constructed context, so for now it exposes the internally caught exception as the cause so that full information about the context of the error is maintained. Fixes: #4849 Change-Id: I55a86b29023675d9e5e49bc7edc5a2dc0bcd4751
* Remove print statement in favor of print() function in docs and examplesAlbert Tugushev2020-02-261-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | <!-- Provide a general summary of your proposed changes in the Title field above --> ### Description <!-- Describe your changes in detail --> Remove print statements ### Checklist <!-- go over following points. check them with an `x` if they do apply, (they turn into clickable checkboxes once the PR is submitted, so no need to do everything at once) --> This pull request is: - [X] A documentation / typographical error fix - Good to go, no issue or tests are needed - [ ] A short code fix - please include the issue number, and create an issue if none exists, which must include a complete example of the issue. one line code fixes without an issue and demonstration will not be accepted. - Please include: `Fixes: #<issue number>` in the commit message - please include tests. one line code fixes without tests will not be accepted. - [ ] A new feature implementation - please include the issue number, and create an issue if none exists, which must include a complete example of how the feature would look. - Please include: `Fixes: #<issue number>` in the commit message - please include tests. **Have a nice day!** Closes: #5166 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5166 Pull-request-sha: 04a7394f71298322188f0861b4dfe93e5485839d Change-Id: Ib90a59fac929661a18748c6e44966fb87e3978c6
* Ensure descendants of mixins don't become cacheableMike Bayer2020-02-221-9/+13
| | | | | | | | | | HasPrefix / HasSuffixes / SupportsCloneAnnotations exported a _traverse_internals attribute that does not represent a complete traversal, meaning non-traversible subclasses would seem traversible. rename these attributes so that this does not occur. DML is currently not traversible (will be soon). Change-Id: I2605e61c8c3d49965335e66e09f4aeedc5e73bd3
* Merge remote-tracking branch 'origin/pr/5141'Mike Bayer2020-02-221-3/+3
|\ | | | | | | Change-Id: If7e15115de22b0aa562a93f09d2287966914d96c
| * fix documentation typosFederico Caselli2020-02-081-3/+3
| | | | | | | | Change-Id: I4376910ae1cf6bf27226f049d4cf2d0e6ba2a83b
* | Result initial introductionMike Bayer2020-02-211-1/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This builds on cc718cccc0bf8a01abdf4068c7ea4f3 which moved RowProxy to Row, allowing Row to be more like a named tuple. - KeyedTuple in ORM is replaced with Row - ResultSetMetaData broken out into "simple" and "cursor" versions for ORM and Core, as well as LegacyCursor version. - Row now has _mapping attribute that supplies full mapping behavior. Row and SimpleRow both have named tuple behavior otherwise. LegacyRow has some mapping features on the tuple which emit deprecation warnings (e.g. keys(), values(), etc). the biggest change for mapping->tuple is the behavior of __contains__ which moves from testing of "key in row" to "value in row". - ResultProxy breaks into ResultProxy and FutureResult (interim), the latter has the newer APIs. Made available to dialects using execution options. - internal reflection methods and most tests move off of implicit Row mapping behavior and move to row._mapping, result.mappings() method using future result - a new strategy system for cursor handling replaces the various subclasses of RowProxy - some execution context adjustments. We will leave EC in but refined things like get_result_proxy() and out parameter handling. Dialects for 1.4 will need to adjust from get_result_proxy() to get_result_cursor_strategy(), if they are using this method - out parameter handling now accommodated by get_out_parameter_values() EC method. Oracle changes for this. external dialect for DB2 for example will also need to adjust for this. - deprecate case_insensitive flag for engine / result, this feature is not used mapping-methods on Row are deprecated, and replaced with Row._mapping.<meth>, including: row.keys() -> use row._mapping.keys() row.items() -> use row._mapping.items() row.values() -> use row._mapping.values() key in row -> use key in row._mapping int in row -> use int < len(row) Fixes: #4710 Fixes: #4878 Change-Id: Ieb9085e9bcff564359095b754da9ae0af55679f0
* | Create initial future package, RemovedIn20WarningMike Bayer2020-02-121-30/+95
|/ | | | | | | | | | | | | | | | | Reorganization of Select() is the first major element of the 2.0 restructuring. In order to start this we need to first create the new Select constructor and apply legacy elements to the old one. This in turn necessitates starting up the RemovedIn20Warning concept which itself need to refer to "sqlalchemy.future", so begin to establish this basic framework. Additionally, update the DML constructors with the newer no-keyword style. Remove the use of the "pending deprecation" and fix Query.add_column() deprecation which was not acting as deprecated. Fixes: #4845 Fixes: #4648 Change-Id: I0c7a22b2841a985e1c379a0bb6c94089aae6264c
* apply asbool reduction to the onclause in join()Mike Bayer2020-01-171-1/+1
| | | | | | | | | | The :func:`.true` and :func:`.false` operators may now be applied as the "onclause" of a :func:`.sql.join` on a backend that does not support "native boolean" expressions, e.g. Oracle or SQL Server, and the expression will render as "1=1" for true and "1=0" false. This is the behavior that was introduced many years ago in :ticket:`2804` for and/or expressions. Change-Id: I85311c31c22d6e226c618f8840f6b95eca611153
* Enable F821Mike Bayer2020-01-041-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | In Ia63a510f9c1d08b055eef62cf047f1f427f0450c we introduced "lambda combinations" which use a bit of function closure inspection in order to allow for testing combinations that make use of symbols that come from test fixtures, or from the test itself. Two problems. One is that we can't use F821 flake8 rule without either adding lots of noqas, skipping the file, or adding arguments to the lambdas themselves that are then populated, which makes for a very verbose system. The other is that the system is already verbose with all those lambdas and the magic in use is a non-explicit kind, hence F821 reminds us that if we can improve upon this, we should. So let's improve upon it by making it so that the "lambda" is just once and up front for the whole thing, and let it accept the arguments directly. This still requires magic, because these test cases need to resolve at test collection time, not test runtime. But we will instead substitute a namespace up front that can be coerced into its desired form within the tests. Additionally, there's a little bit of py2k compatible type annotations present; f821 is checking these, so we have to add those imports also using the TYPE_CHECKING boolean so they don't take place in py2k. Change-Id: Idb7e7a0c8af86d9ab133f548511306ef68cdba14
* happy new yearMike Bayer2020-01-011-1/+1
| | | | Change-Id: I08440dc25e40ea1ccea1778f6ee9e28a00808235
* Test for short term reference cycles and resolve as many as possibleMike Bayer2019-12-301-2/+2
| | | | | | | | Added test support and repaired a wide variety of unnecessary reference cycles created for short-lived objects, mostly in the area of ORM queries. Fixes: #5056 Change-Id: Ifd93856eba550483f95f9ae63d49f36ab068b85a
* Add CTE prefixesMarat Sharafutdinov2019-12-181-3/+17
| | | | | | | | | | | | | Added support for prefixes to the :class:`.CTE` construct, to allow support for Postgresql 12 "MATERIALIZED" and "NOT MATERIALIZED" phrases. Pull request courtesy Marat Sharafutdinov. Fixes: #5040 Closes: #5043 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5043 Pull-request-sha: d1b9059a0b6dae8dc2479ac670999b4af07908e0 Change-Id: I2e9cb5d7f85961ec98ee51965de5b3ec4a97be2f
* Do the CompoundSelect check for number of columns in the compile phaseMike Bayer2019-12-161-25/+6
| | | | | | | | Starting to go forward with the general idea of moving more of Core / ORM construction into the compile phase. Bigger initiatives like the refactor of Query will follow onto this. Change-Id: I0f364d3182e21e32ed85ef34cfd11fd9d11cf653
* Traversal and clause generation performance improvementsMike Bayer2019-12-141-2/+8
| | | | | | | Added one traversal test, callcounts have been brought from 29754 to 5173 so far. Change-Id: I164e9831600709ee214c1379bb215fdad73b39aa
* Use label reference coercion for select() distinct keyword argumentMike Bayer2019-12-061-1/+1
| | | | | | | | | | | Fixed bug where "distinct" keyword passed to :func:`.select` would not treat a string value as a "label reference" in the same way that the :meth:`.select.distinct` does; it would instead raise unconditionally. This keyword argument and the others passed to :func:`.select` will ultimately be deprecated for SQLAlchemy 2.0. Fixes: #5028 Change-Id: Id36cfe477ed836c3248824ce1b81d0016dbe99f4
* Add anonymizing context to cache keys, comparison; convert traversalMike Bayer2019-11-041-248/+148
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Created new visitor system called "internal traversal" that applies a data driven approach to the concept of a class that defines its own traversal steps, in contrast to the existing style of traversal now known as "external traversal" where the visitor class defines the traversal, i.e. the SQLCompiler. The internal traversal system now implements get_children(), _copy_internals(), compare() and _cache_key() for most Core elements. Core elements with special needs like Select still implement some of these methods directly however most of these methods are no longer explicitly implemented. The data-driven system is also applied to ORM elements that take part in SQL expressions so that these objects, like mappers, aliasedclass, query options, etc. can all participate in the cache key process. Still not considered is that this approach to defining traversibility will be used to create some kind of generic introspection system that works across Core / ORM. It's also not clear if real statement caching using the _cache_key() method is feasible, if it is shown that running _cache_key() is nearly as expensive as compiling in any case. Because it is data driven, it is more straightforward to optimize using inlined code, as is the case now, as well as potentially using C code to speed it up. In addition, the caching sytem now accommodates for anonymous name labels, which is essential so that constructs which have anonymous labels can be cacheable, that is, their position within a statement in relation to other anonymous names causes them to generate an integer counter relative to that construct which will be the same every time. Gathering of bound parameters from any cache key generation is also now required as there is no use case for a cache key that does not extract bound parameter values. Applies-to: #4639 Change-Id: I0660584def8627cad566719ee98d3be045db4b8d
* Omit onclause as source of FROMs from a JoinMike Bayer2019-10-091-6/+1
| | | | | | | | | | | | | The :class:`.Join` construct no longer considers the "onclause" as a source of additional FROM objects to be omitted from the FROM list of an enclosing :class:`.Select` object as standalone FROM objects. This applies to an ON clause that includes a reference to another FROM object outside the JOIN; while this is usually not correct from a SQL perspective, it's also incorrect for it to be omitted, and the behavioral change makes the :class:`.Select` / :class:`.Join` behave a bit more intuitively. Fixes: #4621 Change-Id: Iaa1e75b7c59b21e9701ab3c9b69e66930feaf8ee
* Add result map targeting for custom compiled, text objectsMike Bayer2019-10-071-4/+8
| | | | | | | | | | | | | | | | In order for text(), custom compiled objects, etc. to be usable by Query(), they are all targeted by object key in the result map. As we no longer want Query to implicitly label these, as well as that text() has no label feature, support adding entries to the result map that have no name, key, or type, only the object itself, and then ensure that the compiler sets up for positional targeting when this condition is detected. Allows for more flexible ORM query usage with custom expressions and text() while having less special logic in query itself. Fixes: #4887 Change-Id: Ie073da127d292d43cb132a2b31bc90af88bfe2fd
* create second level deduping when use_labels is turned onMike Bayer2019-10-071-6/+51
| | | | | | | | | | | | | | | | | | | | | As of #4753 we allow duplicate columns. This creates some new problems that there can be duplicate columns in a subquery which are then not addressible on the outside because they are ambiguous (Postgresql has this behavior at least). Additionally it creates situations where we are making an anon label of an anon label which is leaking into the query. New logic for generating anon labels handles this situation and also alters the .c collection of a subquery such that we are only getting the first column from the derived selectable that has that name, the subsequent ones have a new deduping label with two underscores and are not exposed in .c. The dedupe logic when rendering the columns will handle duplicate label names for different columns, vs. the same column repeated, as separate cases. Fixes: #4892 Change-Id: I929fbd8da14bcc239e0481c24bbd9b5ce826e8fa
* Deprecate textual column matching in RowMike Bayer2019-10-041-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Deprecate query.instances() without a context Deprecate string alias with contains_eager() Deprecated the behavior by which a :class:`.Column` can be used as the key in a result set row lookup, when that :class:`.Column` is not part of the SQL selectable that is being selected; that is, it is only matched on name. A deprecation warning is now emitted for this case. Various ORM use cases, such as those involving :func:`.text` constructs, have been improved so that this fallback logic is avoided in most cases. Calling the :meth:`.Query.instances` method without passing a :class:`.QueryContext` is deprecated. The original use case for this was that a :class:`.Query` could yield ORM objects when given only the entities to be selected as well as a DBAPI cursor object. However, for this to work correctly there is essential metadata that is passed from a SQLAlchemy :class:`.ResultProxy` that is derived from the mapped column expressions, which comes originally from the :class:`.QueryContext`. To retrieve ORM results from arbitrary SELECT statements, the :meth:`.Query.from_statement` method should be used. Note there is a small bump in test_zoomark because the column._label is being calculated for each of those columns within baseline_3_properties, as it is now part of the result map. This label can't be calculated when the column is attached to the table because it needs to have all the columns present to do this correctly. Another approach here would be to pre-load the _label before the test runs however the zoomark tests don't have an easy place for this to happen and it's not really worth it. Fixes: #4877 Fixes: #4719 Change-Id: I9bd29e72e6dce7c855651d69ba68d7383469acbc
* Unify generation between Core and ORM queryMike Bayer2019-09-261-140/+191
| | | | | | | | | | | | | | generation is to be enhanced to include caching functionality, so ensure that Query and all generative in Core (e.g. select, DML etc) are using the same generations system. Additionally, deprecate Select.append methods and state Select methods independently of their append versions. Mutability of expression objects is a special case only when generating new objects during a visit. Fixes: #4637 Change-Id: I3dfac00d5e0f710c833b236f7a0913e1ca24dde4
* Restore subquery.as_scalar() w/ deprecationMike Bayer2019-09-111-0/+12
| | | | | | | | Apparently Alias had an .as_scalar() method, so restore an equivalent to Subquery with an appropriate deprecation warning. Fixes: #4854 Change-Id: I6255d61b7d82487ca90ba8ee79d4b3a74e7cbe38
* Adjustments to _copy_internals()Mike Bayer2019-09-061-13/+12
| | | | | | | | | | | | We are looking to build a generalization of copy_internals(), so move out any special logic from these methods. Re-implement and clarify rationale for the Alias doesnt copy a TableClause rule as part of the adaption traversal, establish that we forgot to build out comparison and cache key for CTE, remove incomplete _copy_internals() from GenerativeSelect (it doesn't handle the order_by_clause or group_by_clause, so is incomplete) Change-Id: I95039f042503171aade4ba0fabc9b1598e3c49cf
* Annotate session-bind-lookup entity in Query-produced selectablesMike Bayer2019-08-301-0/+2
| | | | | | | | | | | | | Added new entity-targeting capabilities to the :class:`.Query` object to help with the case where the :class:`.Session` is using a bind dictionary against mapped classes, rather than a single bind, and the :class:`.Query` is against a Core statement that was ultimately generated from a method such as :meth:`.Query.subquery`; a deep search is performed to locate any ORM entity related to the query in order to locate a mapper if one is not otherwise present. Fixes: #4829 Change-Id: I95cf325a5aba21baec4b313246c6f4d692284820
* Fix typosMin ho Kim2019-07-211-1/+1
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* Allow duplicate columns in from clauses and selectablesMike Bayer2019-07-111-26/+38
| | | | | | | | | | | | | | | | | | The :func:`.select` construct and related constructs now allow for duplication of column labels and columns themselves in the columns clause, mirroring exactly how column expressions were passed in. This allows the tuples returned by an executed result to match what was SELECTed for in the first place, which is how the ORM :class:`.Query` works, so this establishes better cross-compatibility between the two constructs. Additionally, it allows column-positioning-sensitive structures such as UNIONs (i.e. :class:`.CompoundSelect`) to be more intuitively constructed in those cases where a particular column might appear in more than one place. To support this change, the :class:`.ColumnCollection` has been revised to support duplicate columns as well as to allow integer index access. Fixes: #4753 Change-Id: Ie09a8116f05c367995c1e43623c51e07971d3bf0
* class level docstring for SubqueryMike Bayer2019-07-061-0/+26
| | | | | | Remove inherited member doc from most selectables, it's too verbose Change-Id: I1b6635fe73342705846c0fab635b46557e560734
* SelectBase no longer a FromClauseMike Bayer2019-07-061-384/+628
| | | | | | | | | | | | | | | | | | | | As part of the SQLAlchemy 2.0 migration project, a conceptual change has been made to the role of the :class:`.SelectBase` class hierarchy, which is the root of all "SELECT" statement constructs, in that they no longer serve directly as FROM clauses, that is, they no longer subclass :class:`.FromClause`. For end users, the change mostly means that any placement of a :func:`.select` construct in the FROM clause of another :func:`.select` requires first that it be wrapped in a subquery first, which historically is through the use of the :meth:`.SelectBase.alias` method, and is now also available through the use of :meth:`.SelectBase.subquery`. This was usually a requirement in any case since several databases don't accept unnamed SELECT subqueries in their FROM clause in any case. See the documentation in this change for lots more detail. Fixes: #4617 Change-Id: I0f6174ee24b9a1a4529168e52e855e12abd60667
* Rework proxy_cache fix to restore performanceMike Bayer2019-07-021-2/+2
| | | | | | | Adjustment to the fix made in I7fb134cac3604f8fe62e220fb24a0945d0a1c56f. Fixes: #4747 Change-Id: I2f1010b0abc1faa892f5e346e58f9c4a3867622f
* Clear proxy_set cache when creating an annotated columnMike Bayer2019-07-021-1/+0
| | | | | | | | | | | | Fixed an unlikely issue where the "corresponding column" routine for unions and other :class:`.CompoundSelect` objects could return the wrong column in some overlapping column situtations, thus potentially impacting some ORM operations when set operations are in use, if the underlying :func:`.select` constructs were used previously in other similar kinds of routines, due to a cached value not being cleared. Fixes: #4747 Change-Id: I7fb134cac3604f8fe62e220fb24a0945d0a1c56f
* A few doc tweaks for alias / order_by / group_byMike Bayer2019-07-011-11/+59
| | | | Change-Id: Ib3b46b45735529d68ebfb3784de4de5d2d0f4abc
* Turn off the is_literal flag when proxying literal_column() to LabelMike Bayer2019-06-151-1/+0
| | | | | | | | | | | | | | | | | | | Fixed a series of quoting issues which all stemmed from the concept of the :func:`.literal_column` construct, which when being "proxied" through a subquery to be referred towards by a label that matches its text, the label would not have quoting rules applied to it, even if the string in the :class:`.Label` were set up as a :class:`.quoted_name` construct. Not applying quoting to the text of the :class:`.Label` is a bug because this text is strictly a SQL identifier name and not a SQL expression, and the string should not have quotes embedded into it already unlike the :func:`.literal_column` which it may be applied towards. The existing behavior of a non-labeled :func:`.literal_column` being propagated as is on the outside of a subquery is maintained in order to help with manual quoting schemes, although it's not clear if valid SQL can be generated for such a construct in any case. Fixes: #4730 Change-Id: I300941f27872fc4298c74a1d1ed65aef1a5cdd82
* Reverse Alias nesting conceptMike Bayer2019-06-131-21/+30
| | | | | | | | | | | | | | | | | | | | | | | | | The Alias object no longer has "element" and "original", it now has "wrapped" and "element" (the name .original is also left as a descriptor for legacy access by third party dialects). These two data members refer to the dual roles Alias needs to play, where in the Python sense it needs to refer to the thing it was applied against directly, whereas in the SQL sense it needs to refer to the ultimate "non-alias" thing it refers towards. Both are necessary to maintain. However, the change here has each Alias object access the non-Alias object immediately so that the "unwrapping" is simpler and does not need any special logic. In the SQL sense, Alias objects don't nest, the only potential was that of the CTE, however there is no such thing as a nested CTE, see link below. This change is an interim change along the way to breaking Alias into more classes and breaking away Select objects from being FromClause objects. Change-Id: Ie7a0d064226cb074ca745505129b5ec7d879e389 References: https://stackoverflow.com/questions/1413516/can-you-create-nested-with-clauses-for-common-table-expressions
* Use roles for ORM alias() conversionMike Bayer2019-05-271-3/+39
| | | | | | | | as SELECT statements will have subquery() and not alias(), start getting ready for the places where the ORM coerces SELECTs into subqueries and be ready to warn about it Change-Id: I90d4b6cae2c72816c6b192016ce074589caf4731
* Implement new ClauseElement role and coercion systemMike Bayer2019-05-181-147/+157
| | | | | | | | | | | | | | | | | | | | A major refactoring of all the functions handle all detection of Core argument types as well as perform coercions into a new class hierarchy based on "roles", each of which identify a syntactical location within a SQL statement. In contrast to the ClauseElement hierarchy that identifies "what" each object is syntactically, the SQLRole hierarchy identifies the "where does it go" of each object syntactically. From this we define a consistent type checking and coercion system that establishes well defined behviors. This is a breakout of the patch that is reorganizing select() constructs to no longer be in the FromClause hierarchy. Also includes a rename of as_scalar() into scalar_subquery(); deprecates automatic coercion to scalar_subquery(). Partially-fixes: #4617 Change-Id: I26f1e78898693c6b99ef7ea2f4e7dfd0e8e1a1bd
* - fix long lineMike Bayer2019-05-091-1/+2
| | | | Change-Id: If44d364ae02da447169a3dc51b6514225578cf82
* Add documentation for MySQL optimizer hints using prefix_withMike Bayer2019-05-081-0/+7
| | | | | Fixes: #4667 Change-Id: Iac3345319dc7c5a20bc7a6520492d2f341b64807
* Add _cache_key implementation.Mike Bayer2019-04-291-0/+98
| | | | | | | This leverages the work started in #4336 to allow ClauseElement structures to be cachable based on structure, not just identity. Change-Id: Ia99ddeb5353496dd7d61243245685f02b98d8100
* Reimplement .compare() in terms of a visitorMike Bayer2019-04-291-0/+9
| | | | | | | | | | | | Reworked the :meth:`.ClauseElement.compare` methods in terms of a new visitor-based approach, and additionally added test coverage ensuring that all :class:`.ClauseElement` subclasses can be accurately compared against each other in terms of structure. Structural comparison capability is used to a small degree within the ORM currently, however it also may form the basis for new caching features. Fixes: #4336 Change-Id: I581b667d8e1642a6c27165cc9f4aded1c66effc6
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