Combining SDO_JOIN with other spatial selections

Question

Hello Forum,
I would like to use SDO_JOIN in combination with other spatial selections on the same set of geometries. e.g. first select a set of lines using SDO_WITHIN_DISTANCE, then joining these upon each other using SDO_JOIN, the latter much like the "cola markets" example
If I do something like this:
select /*+ ordered */ a.shape AS aSHAPE,
b.id as bd,
b.shape AS bSHAPE
from TABLE(SDO_JOIN(table1, shape, tabel1, shape, anyinteract)),
table1 a,
table1 b
WHERE joinrelations,
AND SDO_WITHIN_DISTANCE( b.SHAPE, apoint, adistance)
this works, but is very slow.
I get the impression that sdo_join is performed before selecting the data using sdo_within_distance. As I have very large tables, I would prefer something like:
select /*+ ordered */ a.shape AS aSHAPE,
b.id as bd,
b.shape AS bSHAPE
from TABLE(SDO_JOIN(RESULTSET_OF_SDO_WITHIN_DISTANCE)),
table1 a,
table1 b
WHERE joinrelations
where RESULTSET_OF_SDO_WITHIN_DISTANCE is a query result of the SDO_WITHIN_DISTANCE, however I don't know how to get the syntax right (or if this is even possible)
thanks in advance,
Niels

Answer 1

Hello Bryan,
thanks for your response.
I have a network of segments (all in 1 table) and want to find all segments that are:
- within a certain distance of one segment
- physically linked to this segment
The combination of these should mimic a network trace
To get the distance I plan on using SDO_WITHIN_DISTANCE( b.SHAPE, apoint, adistance)
where b.shape is the geom column of the segments table
Next I plan on joining the result set onto itself using sdo_join, much like the exampe given in the spatial users guide, for the function sdo_join:
SELECT a.name, b.name FROM cola_markets a, cola_markets b,
TABLE(SDO_JOIN('COLA_MARKETS', 'SHAPE', 'COLA_MARKETS', 'SHAPE',
'mask=ANYINTERACT')) c
WHERE c.rowid1 = a.rowid AND c.rowid2 = b.rowid ORDER BY a.name;
The above selects the marktes that have any spatial interaction.
My join releations are very much alike the ones in this example
I need to determine the the spatial interaction as not all segements within the given distance are connected to the selected segment.
As I said before the amount of data is too large to first sdo_join everything, them make the spatial selection, so I was hoping on reversing the prves, first making the spatial selection, then sdo_join'ing the result set.
thanks for any ideas
Niels