From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sat, 4 Jan 2020 18:34:45 +0000 (-0500)
Subject: Add missing changelog file for #5074
X-Git-Tag: rel_1_4_0b1~568
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d9dda8b94036dd5c76968f3ca0d3400f5d765894;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

Add missing changelog file for #5074

The changelog file was missing from
0a8b11bb6528c38dc441caadc6eb2d25046fc376 /
I00b656eb5ee03d87104257a214214617aacae16c.

Fixes: #5074
Change-Id: Ic69fc6b4fb92ed133a14ba36f878f3f4740c565b
---

diff --git a/doc/build/changelog/unreleased_14/5074.rst b/doc/build/changelog/unreleased_14/5074.rst
new file mode 100644
index 0000000000..3b6b951c46
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/5074.rst
@@ -0,0 +1,23 @@
+.. change::
+    :tags: bug, orm
+    :tickets: 5074
+
+    The :class:`.Session` object no longer initates a
+    :class:`.SessionTransaction` object immediately upon construction or after
+    the previous transaction is closed; instead, "autobegin" logic now
+    initiates the new :class:`.SessionTransaction` on demand when it is next
+    needed.  Rationale includes to remove reference cycles from a
+    :class:`.Session` that has been closed out, as well as to remove the
+    overhead incurred by the creation of :class:`.SessionTransaction` objects
+    that are often discarded immediately. This change affects the behavior of
+    the :meth:`.SessionEvents.after_transaction_create` hook in that the event
+    will be emitted when the :class:`.Session` first requires a
+    :class:`.SessionTransaction` be present, rather than whenever the
+    :class:`.Session` were created or the previous :class:`.SessionTransaction`
+    were closed.   Interactions with the :class:`.Engine` and the database
+    itself remain unaffected.
+
+    .. seealso::
+
+        :ref:`change_5074`
+