Node back-end: ensure that Z filtering on regular BB query is materia…

…lized

This materialization is required since Postgres 12. Unfortunately,
inlining this part of the query destroys some estimates and leads to
less ideal plans.

django/applications/catmaid/control/node.py

@@ -1080,8 +1080,10 @@ class Postgis2dNodeProvider(PostgisNodeProvider):
     """
 
     TREENODE_STATEMENT_NAME = PostgisNodeProvider.TREENODE_STATEMENT_NAME + '_2d'
+    # MATERIALIZED seems to be needed at the moment, at least for large queries.
+    # For smaller FOVs, the NOT MATERIALIZED version seems to do better.
     treenode_query = """
-          WITH z_filtered_edge AS (
+          WITH z_filtered_edge AS MATERIALIZED (
             SELECT te.id, te.parent_id, te.edge
             FROM treenode_edge te
             WHERE floatrange(ST_ZMin(te.edge),
@@ -1264,7 +1266,7 @@ class Postgis2dBlurryNodeProvider(PostgisNodeProvider):
 
     TREENODE_STATEMENT_NAME = PostgisNodeProvider.TREENODE_STATEMENT_NAME + '_2d_blurry'
     treenode_query = """
-          WITH z_filtered_edge AS (
+          WITH z_filtered_edge AS MATERIALIZED (
               SELECT te.id, te.parent_id, te.edge
               FROM treenode_edge te
               WHERE floatrange(ST_ZMin(te.edge), ST_ZMax(te.edge), '[]') && floatrange({z1}, {z2}, '[)')