Feature request #16375

Change Way SDO_RELATE is used in QGIS spatial queries

Added by Simon Greener over 2 years ago. Updated almost 2 years ago.

Status:Open
Priority:Normal
Assignee:-
Category:Data Provider/Oracle
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:24285

Description

Background.

I executed an "identify" in QGIS against a single mapped object that comes from an Oracle table with sdo_geometry column.

Using database SQL Trace, I dumped the SQL that QGIS executes and I got the following (which I have compared to the C++ source code):

SELECT "GEOM","ROWID","FID","FID_INT","FID_NUM9","FID_NUM8","FID_NUM7",
"AN_ATTRIBUTE"
FROM
"QGIS"."FOO" "FEATUREREQUEST"
WHERE sdo_filter("GEOM",
mdsys.sdo_geometry(2003,2872,NULL,mdsys.sdo_elem_info_array(1,1003,3),
mdsys.sdo_ordinate_array(5992381.68001308757811785,
2112468.83721287222579122,5992389.06444318685680628,
2112476.22164297243580222)))='TRUE'
AND sdo_relate("GEOM",
mdsys.sdo_geometry(2003,2872,NULL,mdsys.sdo_elem_info_array(1,1003,3),
mdsys.sdo_ordinate_array(5992381.68001308757811785,
2112468.83721287222579122,5992389.06444318685680628,
2112476.22164297243580222)),'mask=ANYINTERACT')='TRUE'

Looking at qgsoracleconn.cpp there's an hasSpatial() method which runs:

"SELECT 1 FROM v$option WHERE parameter='Spatial' AND value='TRUE'"

This is then used at line 96 of qgsoraclefeatureiterator.cpp where it says:

// sdo_relate requires Spatial

If the connection has Spatial, it appends this to the query where clause:

AND sdo_relate(%1,%2,'mask=ANYINTERACT')='TRUE'

Now, SDO_RELATE has always been a Location spatial filter, and so is free for all Oracle users.
Only SDO_GEOM.RELATE requires Spatial in 11g but not 12c.

Additionally, SDO_RELATE is a secondary filter that executes a Primary filter (SDO_FILTER) internally to generate a candidate set of possible objects that are sent to the internal Secondary filter which does the topological analysis.
Even if SDO_RELATE was a licensed filter, it does not need to be used in conjunction with SDO_FILTER.
Additionally, the Oracle Query Optimizer is still not smart enough to realise that the SDO_FILTER is not needed so the use of it with SDO_RELATE doubles the primary filtering.
So the above query should always be running SDO_RELATE… ANYINTERACT and leaving out the SDO_FILTER part.
But, also, the "mask=ANYINTERACT" should be a bind variable as it could be set to "mask=CONTAINS" etc.

In summary (the sentences in bold are the requested functional changes):

1. SDO_RELATE is a free function and not subject to Spatial licensing
- the hasSpatial() test in the C++ is invalid and should be removed;
2. SDO_GEOM.RELATE is a spatial function up till 12c and free afterwards
- AFAIK QGIS currently doesn't use SDO_GEOM.RELATE;
3. Because SDO_RELATE executes its own primary filtering, SDO_FILTER is not needed
- Modify the C++ to remove SDO_FILTER when SDO_RELATE is needed.
4. SDO_FILTER mask parameter should be a bind variable.

regards
Simon

History

#2 Updated by Giovanni Manghi over 2 years ago

  • Easy fix? set to No
  • Regression? set to No

#3 Updated by Giovanni Manghi over 2 years ago

  • Tracker changed from Bug report to Feature request
  • Priority changed from High to Normal
  • Description updated (diff)

#4 Updated by Jürgen Fischer almost 2 years ago

  • Assignee deleted (Jürgen Fischer)

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