render select froms first

The FROM clauses that are established on a :func:`_sql.select` construct
when using the :meth:`_sql.Select.select_from` method will now render first
in the FROM clause of the rendered SELECT, which serves to maintain the
ordering of clauses as was passed to the :meth:`_sql.Select.select_from`
method itself without being affected by the presence of those clauses also
being mentioned in other parts of the query. If other elements of the
:class:`_sql.Select` also generate FROM clauses, such as the columns clause
or WHERE clause, these will render after the clauses delivered by
:meth:`_sql.Select.select_from` assuming they were not explictly passed to
:meth:`_sql.Select.select_from` also. This improvement is useful in those
cases where a particular database generates a desirable query plan based on
a particular ordering of FROM clauses and allows full control over the
ordering of FROM clauses.

Fixes: #7888
Change-Id: I740f262a3841f829239011120a59b5e58452db5b

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index 733def377..53dcf51c7 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -4502,6 +4502,7 @@ class SelectState(util.MemoizedSlots, CompileState):
 
         return self._normalize_froms(
             itertools.chain(
+                self.from_clauses,
                 itertools.chain.from_iterable(
                     [
                         element._from_objects
@@ -4514,7 +4515,6 @@ class SelectState(util.MemoizedSlots, CompileState):
                         for element in statement._where_criteria
                     ]
                 ),
-                self.from_clauses,
             ),
             check_statement=statement,
             ambiguous_table_name_map=ambiguous_table_name_map,