georaster - does not store and retrieve statisics values

[ilucena]

The driver is currently swapping mean/median/minimum values when storing it into to the sdo_georaster metadata but after fixing it another problem showed up.

Currently the sdo_georaster metadata does not allow for statistics without median and mode and since the GDAL API does not support those values directly the metadata with "0" on median and mode may create a georaster that does not validate and peopled can't run PL/SQL functions that needs the metadata to be valid or they will get:

ORA-13443: null or invalid values in

The solution would be to look for STATISTICS_MODE and STATISTICS_MEDIAN on the GDAL metadata and validate it. Sometimes the values are just "0" while it is out of range of min and max.

But if that doesn't works the driver should not try to fill the sdo_georaster metadata with incomplete or incorrect statistics values and user would need to enter that information later using sdo_georaster functions on PL/SQL.

[ilucena]

Fixed on revision r26404