diff options
Diffstat (limited to 'sqlglot/optimizer/pushdown_predicates.py')
| -rw-r--r-- | sqlglot/optimizer/pushdown_predicates.py | 42 |
1 files changed, 22 insertions, 20 deletions
diff --git a/sqlglot/optimizer/pushdown_predicates.py b/sqlglot/optimizer/pushdown_predicates.py index ba5c8b5..96dda33 100644 --- a/sqlglot/optimizer/pushdown_predicates.py +++ b/sqlglot/optimizer/pushdown_predicates.py @@ -21,26 +21,28 @@ def pushdown_predicates(expression): sqlglot.Expression: optimized expression """ root = build_scope(expression) - scope_ref_count = root.ref_count() - - for scope in reversed(list(root.traverse())): - select = scope.expression - where = select.args.get("where") - if where: - selected_sources = scope.selected_sources - # a right join can only push down to itself and not the source FROM table - for k, (node, source) in selected_sources.items(): - parent = node.find_ancestor(exp.Join, exp.From) - if isinstance(parent, exp.Join) and parent.side == "RIGHT": - selected_sources = {k: (node, source)} - break - pushdown(where.this, selected_sources, scope_ref_count) - - # joins should only pushdown into itself, not to other joins - # so we limit the selected sources to only itself - for join in select.args.get("joins") or []: - name = join.this.alias_or_name - pushdown(join.args.get("on"), {name: scope.selected_sources[name]}, scope_ref_count) + + if root: + scope_ref_count = root.ref_count() + + for scope in reversed(list(root.traverse())): + select = scope.expression + where = select.args.get("where") + if where: + selected_sources = scope.selected_sources + # a right join can only push down to itself and not the source FROM table + for k, (node, source) in selected_sources.items(): + parent = node.find_ancestor(exp.Join, exp.From) + if isinstance(parent, exp.Join) and parent.side == "RIGHT": + selected_sources = {k: (node, source)} + break + pushdown(where.this, selected_sources, scope_ref_count) + + # joins should only pushdown into itself, not to other joins + # so we limit the selected sources to only itself + for join in select.args.get("joins") or []: + name = join.this.alias_or_name + pushdown(join.args.get("on"), {name: scope.selected_sources[name]}, scope_ref_count) return expression |