[Geotools-commits] svn - r38656 - trunk/docs/user/library/jdbc

[<svn...@os...>]

Author: aaime
Date: 2012-04-03 03:58:10 -0700 (Tue, 03 Apr 2012)
New Revision: 38656

Modified:
   trunk/docs/user/library/jdbc/oracle.rst
Log:
Docs about the geom metadata table added

Modified: trunk/docs/user/library/jdbc/oracle.rst
===================================================================
--- trunk/docs/user/library/jdbc/oracle.rst	2012-04-03 10:49:34 UTC (rev 38655)
+++ trunk/docs/user/library/jdbc/oracle.rst	2012-04-03 10:58:10 UTC (rev 38656)
@@ -58,11 +58,51 @@
 | "Estimated extends" | Use the spatial index information to quickly   |
 |                     | get an estimate of the data bounds             |
 +---------------------+------------------------------------------------+
+| "Geometry metadata  | An alternative table where geometry            |
+| table"              | metadata information can be looked up          |
++---------------------+------------------------------------------------+
 
+
 Example use::
   
   params.put(PostgisDataStoreFactory.LOOSEBBOX, true );
+  
+  
+Geometry metadata table
+^^^^^^^^^^^^^^^^^^^^^^^
 
+The Oracle data store will, by default, look into the ``MDSYS.USER_SDO*`` and ``MDSYS.ALL_SDO*`` views
+to determine the geometry type and native SRID of each geometry column.
+Those views are automatically populated with information about the geometry columns stored in tables that the current
+user owns (for the ``MDSYS.USER_SDO*`` views) or can otherwise access (for the ``MDSYS.ALL_SDO*`` views).
+
+There are a few hiccups in this process:
+
+  * if the connection pool user cannot access the tables (because impersonation is being used) 
+    the MDSYS views will be empty, making it impossible to determine either the geometry type and the native SRID
+  * the geometry type can be specified only while building the spatial indexes, as a index constraint, however 
+    such information is often not included when creating the indexes
+  * the views are populated dynamically based on the current user, if the database has thousands of tables and users
+    the views can become very slow
+    
+Starting with GeoTools 2.7.5 the database administrator can address the above issues by manually creating a geometry metadata table
+describing each geometry column, and then indicate its presence among the Oracle data store connection parameter named *Geometry metadata table*
+(either as a simple table name, or a schema qualified one).
+The table has the following structure (the table name is free, just indicate the one chosen in the data store connection parameter)::
+
+	CREATE TABLE GEOMETRY_COLUMNS(
+	   F_TABLE_SCHEMA VARCHAR(30) NOT NULL, 
+	   F_TABLE_NAME VARCHAR(30) NOT NULL, 
+	   F_GEOMETRY_COLUMN VARCHAR(30) NOT NULL, 
+	   COORD_DIMENSION INTEGER, 
+	   SRID INTEGER NOT NULL, 
+	   TYPE VARCHAR(30) NOT NULL,
+	   UNIQUE(F_TABLE_SCHEMA, F_TABLE_NAME, F_GEOMETRY_COLUMN),
+	   CHECK(TYPE IN ('POINT','LINE', 'POLYGON', 'COLLECTION', 'MULTIPOINT', 'MULTILINE', 'MULTIPOLYGON', 'GEOMETRY') ));
+	   
+When the table is present the store wil first search it for information about each geometry column
+to be classified, and fall back on the MDSYS views only if such table does not contain any information.
+
 Setup
 ^^^^^