Data Structures &
GeoDatabase
NEW!
• In 9.2 the GDBs have significantly
changed
• Mostly for the better
• New names (file, personal, scaleable)
• Easier to move data between GDBs
• Do NOT have to specify the EXTENT
of the GDB – a big problem in 9.1 and
earlier.
The Geodatabase
It is a single container for many
feature classes (FC) (layers,
{themes} of any feature class type)
Quite often the FCs are stored in
Feature Datasets (FDS)
Shapes become Feature Classes (FC)
Data in a FDS can be topologically
linked
GeoDatabase Now
• Three flavors of GDB
– File
– Personal
– Scalable (was called Enterprise)
• Supports a model of topologically
integrated feature classes - 2D & 3D
• Supports Data Models -- ArcHydro
• Use can be simple or very complex!
• In some applications database designers
will be needed to tune the database
operation!
• Can use many different data structures
The possibilities…
From ESRI’s course Learning ArcGIS Desktop
GeoDatabase
• Three flavors of GDB
– File
– Personal
– Scalable (was called Enterprise)
File GDB
• Stored as folders in a file system.
• Can scale up to 1 TB in size.
• This option is the currently
recommended GDB
• Only one user can edit at a time
• Is much faster than other flavors
Personal GDB
• Stored within a Microsoft Access
data file, which is limited in size to 2
GB.
• One editor at a time
Scaleable GDB
• Also called an ArcSDE Geodatabases
• Stored in a relational database using
Oracle, Microsoft SQL Server, IBM
DB2, or IBM Informix.
• These multi-user Geodatabases
require the use of ArcSDE and can be
unlimited in size and numbers of
users.
• Much more complex and require
professional computer types
Scaleable GDB
• Also called an ArcSDE Geodatabases
• Stored in a relational database using
Oracle, Microsoft SQL Server, IBM
DB2, or =
IBM
Informix.
ArcSDE
Spatial
Database Engine
• These multi-user Geodatabases
require the use of ArcSDE and can be
unlimited in size and numbers of
users.
• Much more complex and require
professional computer types
How do they look
• In ArcCatalog
• In Windows Explorer
Catalogof
View
Views
GDB
WE view
Views of GDB
WE view
Catalog View
Advantages of GDBs
• Can be moved as one piece of data
regardless of how much stuff is in it or
where it is!
• Faster (particularly for File GDBs)
• Can use between layer topology for FC in a
FDS
• Can actually get into the Personal GBD
Access database and mess with it (but you
had better know what you are doing!)
Advantages of GDBs
TOPOLOGY?
= one
the piece
arrangement
• Can be moved as
of data that
defines
how point,
line,
and
polygon
features
regardless
of how
much
stuff
is in it
or
where
it is!
share
coincident
geometry.
• Faster (particularly for File GDBs)
examples,
• Can use between layer topology for FC in a
FDS
•Fire hydrants must fall on water mains,
• Can actually get into the Personal GBD
Access database
and mess
it their
(but you
•Adjacent
soil polygons
mustwith
share
had better know what you are doing!)
common boundaries.
Geodatabase
Feature Classes
Feature Dataset
Stand alone
Feature Classes
Source View
Line(arc)
poly
Anno
Table
}
Cover
ArcCatalog view
Display view
point
These are in a
FDS and thus
valves can be
snapped (must
be actually) to
pipes
Cover
}
ArcCatalog view
Display view
More yet: Feature Class (FC)
• Conceptual representation of a category
of geographic features.
• Includes point, line, poly & annotation
• When shapefiles are added to a GDB
their computer representation is
changed
• This is why you cannot drag and drop a
shapefile into a GDB.
• You have to load it or Import it.
Feature Dataset (FDS)
• A collection of feature classes that share
the same spatial reference.
• It is because they share the same spatial
reference that they can participate in
topological relationships with each other.
• Several feature classes with the same
geometry may be stored in the same
feature dataset.
• Object geometry and relationship classes
can also be stored in a feature dataset
GDB
Icons
Feature Dataset
GDB table
GDB
Icons
Feature Dataset
GDB table
GDB
Icons
Feature Dataset
GDB table
Annotation
Vector data: Network
Table Field Properties
• When creating a Feature Class or
table you can specify the number of
fields to be included
• And you can spec settings such as
field type and max. size
• All fields have property default
values, domains, aliases, and null
allowance
Topologies
• Many datasets have features that
could share boundaries or corners
• By creating a Topology you set up
rules defining how features share
their geometries.
• Editing a boundary or vertex shared
by two or more features updates the
shape of all of them.
Topology rules
• Govern the relationships between between
features within a FC or features in
different FCs
• Example: moving a slope boundary in in one
FC could update two slope class polys AND
update a forest stand boundary in another
FC.
• Topology editing tools in ArcMap are used
to create and change the rules
Geometric Networks
• Some vector datasets need to support
connectivity tracing and network
connectivity rules
– Communications
– Pipelines
– Transportation (roads, railroads, canals)
• Geometric networks allow you to turn
simple point and line features into network
edge and junction features
Summary of data types
Name
Range,
length
Size
(bytes)
Applications
Short
Integer
-32,768 to
32,767
2
No fractions
Long
Integer
-2,147,483,648
To
2,147,483,647
4
No fractions
Float
~-34E-38 to
~1.2E38
4
Fractional values
Summary of data types
Name
Range,
length
Double
~ -2.2E-308
~ 1.8E308
Text
<=64,000
char
Date
mm/dd/yy
hh:mm:ss
Size
(bytes)
8
Applications
Fractions OK
varies Names etc.
8
Date and time
Creating a GDB
• In ArcCatalog!
• Point to where you want to put the
new GDB
• Click New>Personal GDB
• Type in a new name
Adding data
• In Catalog…
Right click and select New
• You get
Copying data
• You can copy/paste data between
GDBs
• OR
• You can import shapefiles, coverages,
computer-aided drafting (CAD) data,
and GeoDatabase FCs into a GDB
Importing shapefiles
• feature class that's in another
coordinate system.
– You MUST project to the spatial
definition of the GDB
– Then right click on
GDB and select
Import --------- 
Planning
• What is the problem?
• What data is needed (scale, extent,
etc.0?
• What kinds of relationships are needed
between FC?
• How will the data be organized (FDS)?
SUMMARY
• The new GDB structure is much
improved
• Easier to use
• 3 kinds
• Drop and drag between GDBs
• Extent does not have to be defined
before creating