Update a "point" table with the poly_id the point belongs to

Question

Sorry, I'm re-posting this message as I initially included in my previous question!
Hi,
Dan, thanks for your help on "improving performance in loading spatial data" question.
Yes, after droping the spatial index it worked much quicker!
Now I have another problem with the table I've managed to populate at a decent speed (with your help!)
There is a column, poly_id which is the polygon the point belongs to. There is another table that stores all the polygons.
I tried the following PL/SQL code but again, it takes ages to run, regardless of having the table indexed or not.
So the tables are
Measurements - unit_id, start_time,relative_time,meas_point,meas_type,dv_id,poly_id
and
areas - poly_id,poly_name,polygon,layer
And the code is
PROCEDURE upd_meas
IS
CURSOR pos_cur IS
SELECT * FROM measurements;
BEGIN
FOR pos_rec IN pos_cur LOOP
UPDATE measurements SET poly_id = (select poly_id from areas a WHERE layer='MAR'
and mdsys.sdo_filter(a.polygon,pos_rec.meas_point,'querytype=WINDOW' ) = 'TRUE'
and rownum =1)
WHERE relative_time=pos_rec.relative_time
AND meas_type=pos_rec.meas_type
AND unit_id=pos_rec.unit_id;
COMMIT;
END LOOP;
END;
Any hint on how to improve the performance? I've also tried sdo_relate without any difference in the execution time.
With thanks in advance,
Silvia

Answer 1

Hi Silvia,
Is there an index on the layer column in the areas table? If so, you may want to use the noindex hint
so it doesn't get used instead of the spatial index. For more info on hints check the Oracle doc for
Designing an Tuning for Performance.
I would use SQL*PLUS to prototype getting a fast response from a filter or relate call (only - not in the context
of the update statement), then use that syntax in spatial portion of the pl/sql update statement.
The spatial portion of the query to test might look something like this:
select /*+NO_INDEX(a layer_idx_name) */  poly_id from areas a WHERE layer='MAR'
and mdsys.sdo_filter(a.polygon,pos_rec.meas_point,'querytype=WINDOW' ) = 'TRUE'
and rownum =1;
or
select /*+ index (a polygon_spatial_idx_name) */...
Hope this helps,
Dan