diff options
Diffstat (limited to 'django/db/models/sql')
| -rw-r--r-- | django/db/models/sql/query.py | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py index fd2e7a6d9a..e5e11f472a 100644 --- a/django/db/models/sql/query.py +++ b/django/db/models/sql/query.py @@ -1105,7 +1105,10 @@ class Query(object): # Process the join list to see if we can remove any inner joins from # the far end (fewer tables in a query is better). - col, alias, join_list = self.trim_joins(target, join_list, last, trim) + nonnull_comparison = (lookup_type == 'isnull' and value is False) + col, alias, join_list = self.trim_joins(target, join_list, last, trim, + nonnull_comparison) + if connector == OR: # Some joins may need to be promoted when adding a new filter to a # disjunction. We walk the list of new joins and where it diverges @@ -1442,7 +1445,7 @@ class Query(object): return field, target, opts, joins, last, extra_filters - def trim_joins(self, target, join_list, last, trim): + def trim_joins(self, target, join_list, last, trim, nonnull_check=False): """ Sometimes joins at the end of a multi-table sequence can be trimmed. If the final join is against the same column as we are comparing against, @@ -1463,6 +1466,11 @@ class Query(object): trimmed before anything. See the documentation of add_filter() for details about this. + The 'nonnull_check' parameter is True when we are using inner joins + between tables explicitly to exclude NULL entries. In that case, the + tables shouldn't be trimmed, because the very action of joining to them + alters the result set. + Returns the final active column and table alias and the new active join_list. """ @@ -1470,7 +1478,7 @@ class Query(object): penultimate = last.pop() if penultimate == final: penultimate = last.pop() - if trim and len(join_list) > 1: + if trim and final > 1: extra = join_list[penultimate:] join_list = join_list[:penultimate] final = penultimate @@ -1483,12 +1491,13 @@ class Query(object): alias = join_list[-1] while final > 1: join = self.alias_map[alias] - if col != join[RHS_JOIN_COL] or join[JOIN_TYPE] != self.INNER: + if (col != join[RHS_JOIN_COL] or join[JOIN_TYPE] != self.INNER or + nonnull_check): break self.unref_alias(alias) alias = join[LHS_ALIAS] col = join[LHS_JOIN_COL] - join_list = join_list[:-1] + join_list.pop() final -= 1 if final == penultimate: penultimate = last.pop() |