Several weeks of using the future_select() construct has led to the proposal there be just one select() construct again which features the new join() method, and otherwise accepts both the 1.x and 2.x argument styles. This would make migration simpler and reduce confusion. However, confusion may be increased by the fact that select().join() is different Current thinking is we may be better off with a few hard behavioral changes to old and relatively unknown APIs rather than trying to play both sides within two extremely similar but subtly different APIs. At the moment, the .join() thing seems to be the only behavioral change that occurs without the user taking any explicit steps. Session.execute() will still behave the old way as we are adding a future flag. This change also adds the "future" flag to Session() and session.execute(), so that interpretation of the incoming statement, as well as that the new style result is returned, does not occur for existing applications unless they add the use of this flag. The change in general is moving the "removed in 2.0" system further along where we want the test suite to fully pass even if the SQLALCHEMY_WARN_20 flag is set. Get many tests to pass when SQLALCHEMY_WARN_20 is set; this should be ongoing after this patch merges. Improve the RemovedIn20 warning; these are all deprecated "since" 1.4, so ensure that's what the messages read. Make sure the inforamtion link is on all warnings. Add deprecation warnings for parameters present and add warnings to all FromClause.select() types of methods. Fixes: #5379 Fixes: #5284 Change-Id: I765a0b912b3dcd0e995426427d8bb7997cbffd51 References: #5159
A variety of caching issues found by running all tests with statement caching turned on. The cache system now has a more conservative approach where any subclass of a SQL element will by default invalidate the cache key unless it adds the flag inherit_cache=True at the class level, or if it implements its own caching. Add working caching to a few elements that were omitted previously; fix some caching implementations to suit lesser used edge cases such as json casts and array slices. Refine the way BaseCursorResult and CursorMetaData interact with caching; to suit cases like Alembic modifying table structures, don't cache the cursor metadata if it were created against a cursor.description using non-positional matching, e.g. "select *". if a table re-ordered its columns or added/removed, now that data is obsolete. Additionally we have to adapt the cursor metadata _keymap regardless of if we just processed cursor.description, because if we ran against a cached SQLCompiler we won't have the right columns in _keymap. Other refinements to how and when we do this adaption as some weird cases were exposed in the Postgresql dialect, a text() construct that names just one column that is not actually in the statement. Fixed that also as it looks like a cut-and-paste artifact that doesn't actually affect anything. Various issues with re-use of compiled result maps and cursor metadata in conjunction with tables being changed, such as change in order of columns. mappers can be cleared but the class remains, meaning a mapper has to use itself as the cache key not the class. lots of bound parameter / literal issues, due to Alembic creating a straight subclass of bindparam that renders inline directly. While we can update Alembic to not do this, we have to assume other people might be doing this, so bindparam() implements the inherit_cache=True logic as well that was a bit involved. turn on cache stats in logging. Includes a fix to subqueryloader which moves all setup to the create_row_processor() phase and elminates any storage within the compiled context. This includes some changes to create_row_processor() signature and a revising of the technique used to determine if the loader can participate in polymorphic queries, which is also applied to selectinloading. DML update.values() and ordered_values() now coerces the keys as we have tests that pass an arbitrary class here which only includes __clause_element__(), so the key can't be cached unless it is coerced. this in turn changed how composite attributes support bulk update to use the standard approach of ClauseElement with annotations that are parsed in the ORM context. memory profiling successfully caught that the Session from Query was getting passed into _statement_20() so that was a big win for that test suite. Apparently Compiler had .execute() and .scalar() methods stuck on it, these date back to version 0.4 and there was a single test in the PostgreSQL dialect tests that exercised it for no apparent reason. Removed these methods as well as the concept of a Compiler holding onto a "bind". Fixes: #5386 Change-Id: I990b43aab96b42665af1b2187ad6020bee778784
This commit includes that we've removed the "_orm_query" attribute from compile state as well as query context. The attribute created reference cycles and also added method call overhead. As part of this change, the interface for ORMExecuteState changes a bit, as well as the interface for the horizontal sharding extension which now deprecates the "query_chooser" callable in favor of "execute_chooser", which receives the contextual object. This will also work more nicely when we implement the new execution path for bulk updates and deletes. Pre-merge execution options for statement, connection, arguments all up front in Connection. that way they can be passed to the before_execute / after_execute events, and the ExecutionContext doesn't have to merge as second time. Core execute is pretty close to 1.3 now. baked wasn't using the new one()/first()/one_or_none() methods, fixed that. Convert non-buffered cursor strategy to be a stateless singleton. inline all the paths by which the strategy gets chosen, oracle and SQL Server dialects make use of the already-invoked post_exec() hook to establish the alternate strategies, and this is actually much nicer than it was before. Add caching to mapper instance processor for getters. Identified a reference cycle per query that was showing up as a lot of gc cleanup, fixed that. After all that, performance not budging much. Even test_baked_query now runs with significantly fewer function calls than 1.3, still 40% slower. Basically something about the new patterns just makes this slower and while I've walked a whole bunch of them back, it hardly makes a dent. that said, the performance issues are relatively small, in the 20-40% time increase range, and the new caching feature does provide for regular ORM and Core queries that are cached, and they are faster than non-cached. Change-Id: I7b0b0d8ca550c05f79e82f75cd8eff0bbfade053
This patch replaces the ORM execution flow with a single pathway through Session.execute() for all queries, including Core and ORM. Currently included is full support for ORM Query, Query.from_statement(), select(), as well as the baked query and horizontal shard systems. Initial changes have also been made to the dogpile caching example, which like baked query makes use of a new ORM-specific execution hook that replaces the use of both QueryEvents.before_compile() as well as Query._execute_and_instances() as the central ORM interception hooks. select() and Query() constructs alike can be passed to Session.execute() where they will return ORM results in a Results object. This API is currently used internally by Query. Full support for Session.execute()->results to behave in a fully 2.0 fashion will be in later changesets. bulk update/delete with ORM support will also be delivered via the update() and delete() constructs, however these have not yet been adapted to the new system and may follow in a subsequent update. Performance is also beginning to lag as of this commit and some previous ones. It is hoped that a few central functions such as the coercions functions can be rewritten in C to re-gain performance. Additionally, query caching is now available and some subsequent patches will attempt to cache more of the per-execution work from the ORM layer, e.g. column getters and adapters. This patch also contains initial "turn on" of the caching system enginewide via the query_cache_size parameter to create_engine(). Still defaulting at zero for "no caching". The caching system still needs adjustments in order to gain adequate performance. Change-Id: I047a7ebb26aa85dc01f6789fac2bff561dcd555d
Convert Query to do virtually all compile state computation in the _compile_context() phase, and organize it all such that a plain select() construct may also be used as the source of information in order to generate ORM query state. This makes it such that Query is not needed except for its additional methods like from_self() which are all to be deprecated. The construction of ORM state will occur beyond the caching boundary when the new execution model is integrated. future select() gains a working join() and filter_by() method. as we continue to rebase and merge each commit in the steps, callcounts continue to bump around. will have to look at the final result when it's all in. References: #5159 References: #4705 References: #4639 References: #4871 References: #5010 Change-Id: I19e05b3424b07114cce6c439b05198ac47f7ac10
towards the goal of reducing verbosity and repetition in test fixtures as well as that we are moving to connection only for execution, move the insert_data() classmethod to accept a connection and adjust all fixtures to use it. Change-Id: I3bf534acca0d5f4cda1d4da8ae91f1155b829b09
Modified the queries used by subqueryload and selectinload to no longer ORDER BY the primary key of the parent entity; this ordering was there to allow the rows as they come in to be copied into lists directly with a minimal level of Python-side collation. However, these ORDER BY clauses can negatively impact the performance of the query as in many scenarios these columns are derived from a subquery or are otherwise not actual primary key columns such that SQL planners cannot make use of indexes. The Python-side collation uses the native itertools.group_by() to collate the incoming rows, and has been modified to allow multiple row-groups-per-parent to be assembled together using list.extend(), which should still allow for relatively fast Python-side performance. There will still be an ORDER BY present for a relationship that includes an explicit order_by parameter, however this is the only ORDER BY that will be added to the query for both kinds of loading. Fixes: #5162 Change-Id: I8befd1303c1af7cc24cbf005f39bc01c8b2745f3
Enhanced logic that tracks if relationships will be conflicting with each other when they write to the same column to include simple cases of two relationships that should have a "backref" between them. This means that if two relationships are not viewonly, are not linked with back_populates and are not otherwise in an inheriting sibling/overriding arrangement, and will populate the same foreign key column, a warning is emitted at mapper configuration time warning that a conflict may arise. A new parameter :paramref:`.relationship.overlaps` is added to suit those very rare cases where such an overlapping persistence arrangement may be unavoidable. Fixes: #5171 Change-Id: Ifae5998fc1c7e49ce059aec8a67c80cabee768ad
Fixed bug where usage of joined eager loading would not properly wrap the query inside of a subquery when :meth:`.Query.group_by` were used against the query. When any kind of result-limiting approach is used, such as DISTINCT, LIMIT, OFFSET, joined eager loading embeds the row-limited query inside of a subquery so that the collection results are not impacted. For some reason, the presence of GROUP BY was never included in this criterion, even though it has a similar effect as using DISTINCT. Additionally, the bug would prevent using GROUP BY at all for a joined eager load query for most database platforms which forbid non-aggregated, non-grouped columns from being in the query, as the additional columns for the joined eager load would not be accepted by the database. Fixes: #5065 Change-Id: I9a2ed8196f83297ec38012138d1a5acdf9e88155
In the interests of making Query much more lightweight up front, rework the calculations done at the top when the entities are constructed to be much less inolved. Use the new coercion system for _ColumnEntity and stop accepting plain strings, this will need to emit a deprecation warning in 1.3.x. Use annotations and other techniques to reduce the decisionmaking and complexity of Query. For the use case of subquery(), .statement, etc. we would like to do minimal work in order to get the columns clause. Change-Id: I7e459bbd3bb10ec71235f75ef4f3b0a969bec590