Speed up query logic

Author: webb-ben

pygeoapi/provider/mvt_postgresql.py

@@ -141,29 +141,35 @@ def get_tiles(self, layer='default', tileset=None,
             LOGGER.warning(f'Tile {z}/{x}/{y} not found')
             return ProviderTileNotFoundError
 
-        geom_column = func.ST_CurveToLine(getattr(self.table_model, self.geom))
+        storage_srid = get_crs_from_uri(self.storage_crs).to_string()
+        out_srid = get_crs_from_uri(tileset_schema.crs).to_string()
+
         tile_envelope = func.ST_TileEnvelope(z, x, y)
-        if tileset_schema.crs != self.storage_crs:
-            target_srid = get_crs_from_uri(tileset_schema.crs).to_string()
-            LOGGER.debug(f'Transforming geometry to {target_srid}')
+        envelope = (
+            select(tile_envelope.label('bounds'))
+            .cte('envelope')
+        )
 
-            geom_column = func.ST_Transform(geom_column, target_srid)
-            tile_envelope = func.ST_Transform(tile_envelope, target_srid)
+        geom_column = getattr(self.table_model, self.geom)
+        mvtgeom = (
+            func.ST_AsMVTGeom(
+                func.ST_Transform(geom_column, out_srid),
+                func.ST_Transform(envelope.c.bounds, out_srid))
+            .label('mvtgeom')
+        )
 
-        mvt_columns = [
-            *self.get_fields(),
-            func.ST_AsMVTGeom(geom_column, tile_envelope)
-        ]
-        mvt_query = select(
-            func.ST_AsMVT(
-                select(*mvt_columns)
-                .select_from(self.table_model)
-                .cte('mvt')
-                .table_valued(),
-                layer
-            )
+        geom_filter = geom_column.intersects(
+            func.ST_Transform(tile_envelope, storage_srid))
+        mvtrow = (
+            select(*self.get_fields(), mvtgeom)
+            .filter(geom_filter)
+            .select_from(self.table_model)
+            .cte('mvtrow')
+            .table_valued()
         )
 
+        mvt_query = select(func.ST_AsMVT(mvtrow, layer))
+
         with Session(self._engine) as session:
             result = session.execute(mvt_query).scalar()