Changeset 8853

Timestamp:

09/02/08 08:52:07 (3 months ago)

Author:

mtredinnick

Message:

Fixed #8790 -- Multi-branch join trees that shared tables of the same name were
sometimes also sharing aliases, instead of creating their own. This was
generating incorrect SQL.

No representative test for this fix yet because I haven't had time to write one
that fits in nicely with the test suite. But it works for the monstrous example
in #8790 and a bunch of other complex examples I've created locally. Will write
a test later.

Files:

• django/trunk/django/db/models/sql/query.py (modified) (9 diffs)

django/trunk/django/db/models/sql/query.py

@@ -659 +659 @@
-
-        # Must use left outer joins for nullable fields.
-
-
-
-
+
-
-        # If we get to this point and the field is a relation to another model,
@@ -745 +742 @@
-        return False
-
+    def promote_alias_chain(self, chain, must_promote=False):
+        """
+        Walks along a chain of aliases, promoting the first nullable join and
+        any joins following that. If 'must_promote' is True, all the aliases in
+        the chain are promoted.
+        """
+        for alias in chain:
+            if self.promote_alias(alias, must_promote):
+                must_promote = True
+
+    def promote_unused_aliases(self, initial_refcounts, used_aliases):
+        """
+        Given a "before" copy of the alias_refcounts dictionary (as
+        'initial_refcounts') and a collection of aliases that may have been
+        changed or created, works out which aliases have been created since
+        then and which ones haven't been used and promotes all of those
+        aliases, plus any children of theirs in the alias tree, to outer joins.
+        """
+        # FIXME: There's some (a lot of!) overlap with the similar OR promotion
+        # in add_filter(). It's not quite identical, but is very similar. So
+        # pulling out the common bits is something for later.
+        considered = {}
+        for alias in self.tables:
+            if alias not in used_aliases:
+                continue
+            if (alias not in initial_refcounts or
+                    self.alias_refcount[alias] == initial_refcounts[alias]):
+                parent = self.alias_map[alias][LHS_ALIAS]
+                must_promote = considered.get(parent, False)
+                promoted = self.promote_alias(alias, must_promote)
+                considered[alias] = must_promote or promoted
+
-    def change_aliases(self, change_map):
-        """
@@ -808 +837 @@
-        should not be changed.
-        """
-
-
+
+
+
+
-        change_map = {}
-        prefix = self.alias_prefix
-        for pos, alias in enumerate(self.tables):
-            if alias in exceptions:
@@ -888 +918 @@
-                        # The LHS of this join tuple is no longer part of the
-                        # query, so skip this possibility.
+                        continue
+                    if self.alias_map[alias][LHS_ALIAS] != lhs:
-                        continue
-                    self.ref_alias(alias)
@@ -1121 +1153 @@
-            join_it.next(), table_it.next()
-            table_promote = False
+            join_promote = False
-            for join in join_it:
-                table = table_it.next()
@@ -1129 +1162 @@
-                    table_promote = self.promote_alias(table)
-                break
-
-
-
-
-
-
-
-
+
+
-
-        self.where.add((alias, col, field, lookup_type, value), connector)
-
-        if negate:
-
-
+
-            if lookup_type != 'isnull':
-                if final > 1:
@@ -1202 +1228 @@
-                    # (they shouldn't turn the whole conditional into the empty
-                    # set just because they don't match anything).
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
+
-                connector = q_object.connector
-            if q_object.negated:
@@ -1440 +1451 @@
-        query = Query(self.model, self.connection)
-        query.add_filter(filter_expr, can_reuse=can_reuse)
+        query.bump_prefix()
-        query.set_start(prefix)
-        query.clear_ordering(True)
@@ -1501 +1513 @@
-                        col = join[LHS_JOIN_COL]
-                        joins = joins[:-1]
-
-
-
-
-
-
+
-                self.select.append((final_alias, col))
-                self.select_fields.append(field)