Database FAQ's
|
 |
This
document contains the answers to frequently asked questions (FAQ)
about Databases.
Questions in this FAQ:
- What is the data structure used
inside Oracle by Cadcorp?
- What do I need to run Oracle and
Cadcorp?
- Why can I not see tables that
I want to connect to with Oracle?
1)
Question: What is the data structure used inside Oracle by Cadcorp?
Answer: Spatial
data can be stored in Oracle in one of the following structures:
Oracle spatial/locator: Spatial
data is stored using the Oracle SDO_Geometry data type. The data
is spatially indexed. Cadcorp SIS reads this data in either a dynamic
mode (with edit capability) or in a cached mode. Oracle supports
the simple features specification for spatial data storage. The
benefit of this data structure is that this is the most widely used
storage mechanism, built around the Open GeoSpatial Consortium specification.
SIS Proprietary Format:
The editable Blobs data format can be used to store data in Oracle.
The format is proprietary to Cadcorp. This format supports: topology
& multi user access. (Note: attribute data cannot be accessed
using SQL). The format of the geometry object can be either+
ASC11 – SIS format for storing topology
WKT – Well Known Text
WKB – Well Known Binary
Open GIS SQL92: This
format uses a database structure stimulated by the Open GIS consortium
to promote interoperability. Attribute data is kept separate from
the geometry data (this allows access to the data using SQL).
2)
Question: What do I need to run Oracle and Cadcorp?
Answer: Using
Oracle Spatial/Locator (sdo_geometry):
To store spatial data in Oracle you must have access to an Oracle
database 9.2.0.5 (standard or enterprise edition). SIS will also need
an Oracle client (version 9.2).
Always ensure that the SIS map window is focused on your geographic
area of interest before reading data from Oracle.
Dynamic connection - to make use of dynamic panning make sure that
a spatial index has been built for your table.
When opening data in a cached mode make sure that a spatial filter
is used, alternatively make sure a suitable ‘WHERE’ clause
is used. If this is not done SIS will attempt to cache the entire
table onto your PC!
Editable Database/View Points/Named tables/Oracle 8i plugin/Open GIS
SQL92;
The datasets mentioned above can be used with either Oracle 8i or
oracle 9i. In either case you must have Oracle installed on the client
and as a database.
Oracle Set up
The database administrator should set up the system to allow the client
to connect to the Oracle database using Oracle net. When connecting
from SIS to Oracle a user will be prompted for the following information:
Username – this is assigned by the database
administrator
Password – this is assigned by the database administrator
Server – The database administrator will set up a connection
name for the Oracle database.
3)
Question: Why can I not see tables that I want to connect to with
Oracle?
Answer: The
option will be greyed out if the table has not been spatially indexed.
If you loaded the data into Oracle using Cadcorp SIS, ensure that
you ticked the ‘Create a Spatial Index’ option when using
the File – Export to Server command. Alternatively, ask your
Oracle DBA to build the spatial index from inside Oracle.
|
|
|
|
|
Technical
FAQ's |
 |
Not what you are looking for, check out frequently
asked questions (FAQ) about:
More information?
Guide
to Transparency in Cadcorp SIS
Cadcorp
SIS Control Development Modules (CDM) - Questions & Answers
Cadcorp
Positional Accuracy Manager
|
