That is, after exhausing all rows using the fetch methods, the DBAPI cursor is released as before and the object may be safely discarded, but the fetch methods may continue to be called for which they will return an end-of-result object (None for fetchone, empty list for fetchmany and fetchall). Only if :meth:`.ResultProxy.close` is called explicitly will these methods raise the "result is closed" error. fixes #3330 fixes #3329
persistence.py could theoretically hit the limit of the cache (100 items by default) and at some points fail to have a key that we check for, due to the cleanup. This has never been observed so its likely that so far, the total number of INSERT, UPDATE and DELETE statement structures in real apps has not exceeded 100 on a per-mapper basis; this could happen for apps that run a very wide variety of attribute modified combinations into the unit of work, *and* which have very high concurrency going on. This change will be a lot more significant when we open up use of LRUCache + compiled cache with the baked query extension.
The "wrapping" employed by the mssql and oracle dialects using the "iswrapper" argument was not being used intelligently by the compiler, and the result map was being written incorrectly, using *more* columns in the result map than were actually returned by the statement, due to "row number" columns that are inside the subquery. The compiler now writes out result map on the "top level" select in all cases fully, and for the mssql/oracle wrapping case extracts out the "proxied" columns in a second step, which only includes those columns that are proxied outwards to the top level. This change might have implications for 3rd party dialects that might be imitating oracle's approach. They can safely continue to use the "iswrapper" kw which is now ignored, but they may need to also add the _select_wraps argument as well.
such that they are matched to the received result set positionally, rather than by name. Originally, this was seen as a way to handle cases where we had columns returned with difficult-to-predict names, though in modern use that issue has been overcome by anonymous labeling. In this version, the approach basically reduces function call count per-result by a few dozen calls, or more for larger sets of result columns. The approach still degrades into a modern version of the old approach if textual elements modify the result map, or if any discrepancy in size exists between the compiled set of columns versus what was received, so there's no issue for partially or fully textual compilation scenarios where these lists might not line up. fixes #918 - callcounts still need to be adjusted down for this so zoomark tests won't pass at the moment
:meth:`.Connection.invalidate` method, or an invalidation due to a database disconnect, would fail if the ``isolation_level`` parameter had been used with :meth:`.Connection.execution_options`; the "finalizer" that resets the isolation level would be called on the no longer opened connection. fixes #3302
with :meth:`.Connection.execution_options` when a :class:`.Transaction` is in play; DBAPIs and/or SQLAlchemy dialects such as psycopg2, MySQLdb may implicitly rollback or commit the transaction, or not change the setting til next transaction, so this is never safe. - Added new parameter :paramref:`.Session.connection.execution_options` which may be used to set up execution options on a :class:`.Connection` when it is first checked out, before the transaction has begun. This is used to set up options such as isolation level on the connection before the transaction starts. - added new documentation section detailing best practices for setting transaction isolation with sessions. fixes #3296
for a for-loop through an empty tuple. we add one more local flag to handle the logic without repetition of dialect.do_execute() calls.
logic to some degree in DefaultExecutionContext. In particular we are removing post_insert() which doesn't appear to be used based on a survey of prominent third party dialects. Callcounts aren't added to existing execute profiling tests and inserts might be a little better. - simplify the execution_options join in DEC. Callcounts don't appear affected.