Forcing one particular query to be rewritten to custom SQL

Question

Hi everyone,
MapBuilder produces Queries that look like this
SELECT ROWID, GEOM, 'C.AT_1410_GW_ROAD', null, 'null', -1, 'rule#0'
FROM MYTABLE
WHERE MDSYS.SDO_FILTER(GEOM, MDSYS.SDO_GEOMETRY(2003, 31468, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 1003, 3), MDSYS.SDO_ORDINATE_ARRAY(:mvqboxxl, :mvqboxyl, :mvqboxxh, :mvqboxyh)), 'querytype=WINDOW') = 'TRUE' AND (areatype = 'ROAD') UNION ALL
SELECT ROWID, GEOM, 'C.AT_1410_GW_RIVER', null, 'null', -1, 'rule#1'
FROM MYTABLE
WHERE MDSYS.SDO_FILTER(GEOM, MDSYS.SDO_GEOMETRY(2003, 31468, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 1003, 3), MDSYS.SDO_ORDINATE_ARRAY(:mvqboxxl, :mvqboxyl, :mvqboxxh, :mvqboxyh)), 'querytype=WINDOW') = 'TRUE' AND (areatype = 'RIVER') UNION ALL
SELECT ROWID, GEOM, 'C.AT_1410_GW_FOREST', null, 'null', -1, 'rule#2'
FROM MYTABLE
WHERE MDSYS.SDO_FILTER(GEOM, MDSYS.SDO_GEOMETRY(2003, 31468, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 1003, 3), MDSYS.SDO_ORDINATE_ARRAY(:mvqboxxl, :mvqboxyl, :mvqboxxh, :mvqboxyh)), 'querytype=WINDOW') = 'TRUE' AND (areatype = 'FOREST') UNION ALL
...Where geom is the sdo_geometry to be drawn and areatype determines the type of which a polygon is (for example a river or forest). As you can see there multiple queries to the same table, union-all'd together. This is unnecessary. It causes a lot of expensive spatial queries when it really only serves to create the literal strings like 'C.AT_1410_GW_ROAD' that MapBuilder needs to distinguish for example forests and rivers.
I was thinking of making a materialized view that contains the literals 'C.AT_1410_GW_ROAD' and so on which MapBuilder/Viewer needs, plus the geometries. That would allow to get the same result in just one simple
SELECT rowid, geom, layertype, null, null, rule
FROM mymatview
WHERE MDSYS.SDO_ORDINATE_ARRAY(:mvqboxxl, :mvqboxyl, :mvqboxxh, :mvqboxyh)), 'querytype=WINDOW') = 'TRUE'Where layertype would contain the 'C.AT_1410_GW_ROAD' and rule the 'rule#0'. Basically the result of the huge union-all-query above, without the bounding box, in an MV. That part works, but now I need Oracle to actually use this MV instead of running the query that MapBuilder sends. How do I do this? I don't think Oracle can realize that the MV has a column containing the literals MapBuilder sends in its SELECT. Basically I need a "query search and replace" in Oracle 11g, or a "custom query rewrite" if that's what you want to call it.
Kind of hard to explain, I hope it is understandable, any help would be very very much appreciated,
Christian
Edited by: Christian Menke on 02.09.2010 07:26
Edited by: Christian Menke on 02.09.2010 07:27

Answer 1

Use the case statement to determine two of the columns, which means you can remove the UNION ALL since there is no difference in the WHERE clause apart from the areatype;
something like this:
SELECT ROWID
      ,GEOM                 as Geom
      ,null                 as Null_value
      ,'null'               as Literal_Null_String
      ,case
          when area_type = 'ROAD' then
            'C.AT_1410_GW_ROAD'
          when area_type = 'RIVER' then
            'C.AT_1410_GW_RIVER'
          when area_type = 'FOREST' then
            'C.AT_1410_GW_FOREST'
       end as location_literal
      ,-1                   as Negative_One
      ,case
          when area_type = 'ROAD' then
            'rule#0'
          when area_type = 'RIVER' then
            'rule#1'
          when area_type = 'FOREST' then
            'rule#2'
       end as rule_string
FROM  MYTABLE
WHERE MDSYS.SDO_FILTER(GEOM, MDSYS.SDO_GEOMETRY(2003, 31468, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 1003, 3), MDSYS.SDO_ORDINATE_ARRAY(:mvqboxxl, :mvqboxyl, :mvqboxxh, :mvqboxyh)), 'querytype=WINDOW') = 'TRUE'