diff options
Diffstat (limited to 'django/db/models/sql')
| -rw-r--r-- | django/db/models/sql/query.py | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py index e6a3cd2679..e3e3585a8e 100644 --- a/django/db/models/sql/query.py +++ b/django/db/models/sql/query.py @@ -631,8 +631,10 @@ class Query(object): # We have to do the same "final join" optimisation as in # add_filter, since the final column might not otherwise be part of # the select set (so we can't order on it). - join = self.alias_map[alias] - if col == join[RHS_JOIN_COL]: + while 1: + join = self.alias_map[alias] + if col != join[RHS_JOIN_COL]: + break self.unref_alias(alias) alias = join[LHS_ALIAS] col = join[LHS_JOIN_COL] @@ -830,6 +832,10 @@ class Query(object): if not always_create: for alias in self.join_map.get(t_ident, ()): if alias not in exclusions: + if lhs_table and not self.alias_refcount[self.alias_map[alias][LHS_ALIAS]]: + # The LHS of this join tuple is no longer part of the + # query, so skip this possibility. + continue self.ref_alias(alias) if promote: self.promote_alias(alias) @@ -989,20 +995,22 @@ class Query(object): col = target.column alias = join_list[-1] - if final > 1: + while final > 1: # An optimization: if the final join is against the same column as # we are comparing against, we can go back one step in the join - # chain and compare against the lhs of the join instead. The result - # (potentially) involves one less table join. + # chain and compare against the lhs of the join instead (and then + # repeat the optimization). The result, potentially, involves less + # table joins. join = self.alias_map[alias] - if col == join[RHS_JOIN_COL]: - self.unref_alias(alias) - alias = join[LHS_ALIAS] - col = join[LHS_JOIN_COL] - join_list = join_list[:-1] - final -= 1 - if final == penultimate: - penultimate = last.pop() + if col != join[RHS_JOIN_COL]: + break + self.unref_alias(alias) + alias = join[LHS_ALIAS] + col = join[LHS_JOIN_COL] + join_list = join_list[:-1] + final -= 1 + if final == penultimate: + penultimate = last.pop() if (lookup_type == 'isnull' and value is True and not negate and final > 1): |