3.0 Database Organisation

Within VISION* the schema definition of a database refers to the format and organisation of the user attribute tables as well as the specification of any topological structures such as layers and networks.

The database schema used for DCDB allows us to organise our data in a logical manner which will help simplify and clarify data relationships, and facilitate the users understanding and analysis of the data.

The database schema provides the specification for layers, networks and the definition of feature codes and the user attributes associated with them.

3.1. Explanation of Schema

3.1.1. Layers

The DCDB schema consists of six data layers as outlined under List of User Defined Layers

These layers are used to group features, and networks, which are associated by the type of information they portray, for example, the Stats/Admin Layer only contains feature codes and networks related to statistical and administrative information.

Layers are the second level of the database structure with the map or database being the first level.

The layer structure can be used to assist the management of information in the database. For example, the Content Maintenance facility (cdm) enables various controls to be placed upon the use of information in the database at a layer level. Other programs like gina_out enable data processing to be restricted to selected layers of information.

Symbolisation of data within VISION* can also be controlled at a layer level.

List of User Defined Layers

Layers: Layer number:	Cadastral 100	District 101	Strata 102	Statute 103	Stats/Admin 104	Plan Reference 106
Layer Description:	Cadastral information	Land District Information	Strata Information	Statutory Restrictions	Statistical and Administration Polygons	Plan Reference Information
Comments	All cadastral boundary and Road Information	-	To store a definition of Strata plans	Proclamations of central government importance	Meshblock boundary and identifier information	All Plan references and provisional plans

3.1.2. Networks

These are the next level of the structure below the layers and are further subdivision of the features, contained on a layer, into sub-groups. For example, the Cadastral Layer is divided into seven networks. Networks exist as outlined under List of User Defined Networks.

Each network enables the grouping of features which have some geometrical connectivity or geometrical relationships. Which features are physically connected to other features or which features are next to other features, is known as topology.

Networks may be of two types: Polygon or Linear.

Polygon networks are networks that topology can be created within. A polygon is a closed feature, for example, a parcel of land with topology formed. To form topology and hence create a polygon, a centroid identifier must be placed within the parcel's boundaries, then a relationship between the centroid identifier and the boundaries can be established (topology formation).

Linear networks are networks that only store line or point features which are not intended to form polygons. The lines within these networks may be inter-connected such as on the centrelines network or they may be randomly scattered such as private road boundaries on the private roads network. The relationship between networks and layers is shown in the following diagram.

List of User Defined Networks.

Layers	Cadastral 100	District 101	Strata 102	Statute 103	Stats/Admin 104	Plan Reference 106
Networks	Survey 1000	Land 1011	Parcel Strata 1020	Proclamation 1032	Meshblock 1040	Plan 1060
	Partition 1002				Ward 1043
	Centreline 1005				TA 1044
	Road Legality 1006				Region 1045
	Address 1007				Constituency 1046
	Survey Maint 1008				General 1047
	EMF 1009				Maori 1048
					No Licence 1049

NOTE - The Statute layer (103) and Survey Maint network (1008) are not available for client supply.

3.2. Schema Features

The fundamental database spatial entity is called a feature. A feature has one or more coordinates, an optional graphic text string, optional graphic parameters, (text size and justification for example), system attributes, (feature code, layer and network number, length for example), and optional user defined attributes (appellation, plan number and street address for example). The feature code determines which symbolisation is to be used for a feature, and also determines which attribute table is used for the user defined attributes directly associated with the feature.

The DCDB schema uses three types of features namely: Polygon, Linear, and Point.

The list below shows the features defined in the schema, their type and definition:

Feature	Primary Table	Type	Definition
access_cl	road_cl	Linear	Centreline defining accessways
address	address	Point	Address feature (Road name and property number)
constituency	constituency	Polygon	Regional Constituency polygon centroid
constit_bdy	p_sufi	Linear	Boundary defining Regional Constituency derived from meshblocks.
easement_cl	covenant	Linear	Centreline defining easement in gross
emf	emf	Point	End point marker feature defining source of data
emf1008	emf	Point	Maintenance end point marker feature defining source of data - Not for client supply
general	general	Polygon	General Electorate polygon centroid
general_bdy	p_sufi	Linear	Boundary for General Electorate derived from meshblocks.
hyd_segment	hyd_segment	Polygon	Hydrographic polygon centroid
h_line	p_sufi	Linear	Line used to close off cadastral hydrographic features to ensure polygons are formed. eg. river confluence, river mouth.
land_dist	land_district	Polygon	Land district polygon centroid
ld_bdy	p_sufi	Linear	Land district polygon boundary
m_part_bdy	p_sufi	Linear	Parcel boundaries derived from unsurveyed Maori partitions.
maori	maori	Polygon	Maori Electorate polygon centroid.
maori_bdy	p_sufi	Linear	Boundary for Maori Electorate derived from meshblocks.
maint_bdy	p_sufi	Linear	Maintenance data - Not for client supply
mesh_bdy	p_sufi	Linear	Meshblock boundary feature code cloned from current cadastral boundaries or centrelines. This feature code is used in all client supply.
mesh_cad	p_sufi	Linear	Meshblock boundary following, or derived from, current cadastral boundaries.
mesh_topo	p_sufi	Linear	Meshblock boundary following, or derived from, current topographic features.
mesh_other	p_sufi	Linear	Meshblock boundary following, or derived from, features which are unknown, poorly defined or no longer current.
meshblock	meshblock	Polygon	Meshblock polygon centroid.
no_licence	no_licence	Polygon	Alcohol No Licence District Polygon centroid derived from meshblocks.
no_lic_bdy	p_sufi	Linear	Boundary for Alcohol No Licence District.
parcel	parcel	Polygon	Parcel polygon centroid
parcel02	parcel	Polygon	Maori partition parcel polygon centroid
parcel20	parcel	Polygon	Strata parcel polygon centroid
parcel32	parcel	Polygon	Proclamation parcel polygon centroid
parcel1008	parcel	Polygon	Maintenance parcel polygon centroid - Not for client supply
parcel_arc	p_sufi	Linear	Parcel Arc boundaries. Parcel boundaries which are also arcs.
parcel_arc02	p_sufi	Linear	Maori partition parcel Arc boundaries. Parcel boundaries which are also arcs. Cloned from parcel_arc
parcel_arc20	p_sufi	Linear	Strata parcel Arc boundaries. Parcel boundaries which are also arcs. May be cloned from parcel_arc
parcel_bdy	p_sufi	Linear	Parcel boundaries derived from survey plans.
parcel_bdy02	p_sufi	Linear	Maori partition parcel boundaries derived from survey plans. Cloned from parcel_bdy
parcel_bdy20	p_sufi	Linear	Strata parcel boundaries derived from survey plans. Maybe cloned from parcel_bdy
parcel_hyd	p_sufi	Linear	Surveyed stream/river/lake/coastline edges which are also legal parcel boundaries.
parcel_hyd02	p_sufi	Linear	Surveyed stream/river/lake/coastline edges which are also legal Maori partition parcel boundaries. Cloned from parcel_hyd
plan	surv_plan	Point	Plan feature
plan_prov	surv_plan	Point	Provisional plan feature
proc_bdy	p_sufi	Linear	Boundary defining proclamation
pte_road_cl	road_cl	Linear	Private road centreline.
pte_route_cl	road_cl	Linear	Private route centreline.
r_line	p_sufi	Linear	Boundary to close off road/rail polygons at intersections. Boundary does not coincide with cadastral bdy.
r_line20	p_sufi	Linear	Boundary to close off strata road/rail polygons at intersections. Boundary does not coincide with cadastral bdy.
r_legal_bdy	p_sufi	Linear	Road legality boundary - used internal to road/rail parcel.
r_legal_arc	p_sufi	Linear	Road legality arc boundary - used internal to road/rail parcel.
r_r_arc	p_sufi	Linear	Road/Railway Arc boundaries.
r_r_arc02	p_sufi	Linear	Maori partition Road/Railway Arc boundaries. Cloned from r_r_arc
r_r_arc20	p_sufi	Linear	Strata Road/Railway Arc boundaries. Maybe cloned from r_r_arc
r_r_bdy	p_sufi	Linear	Road/Railway boundaries. Road and/or Railway boundaries derived from survey plans.
r_r_bdy02	p_sufi	Linear	Maori partition Road/Railway boundaries. Road and/or Railway boundaries derived from survey plans. Cloned from r_r_bdy
r_r_bdy20	p_sufi	Linear	Strata Road/Railway boundaries. Road and/or Railway boundaries derived from survey plans. Maybe cloned from r_r_bdy
r_r_hyd	p_sufi	Linear	Surveyed stream/river/lake/coastline edges which are also legal road/rail boundaries.
r_r_hyd02	p_sufi	Linear	Surveyed stream/river/lake/coastline edges which are also legal maori partition road/rail boundaries. Cloned from parcel_hyd
rail_segment	railway	Polygon	Centroid feature used for rail polygon formation
rail_seg20	railway	Polygon	Strata centroid feature used for rail polygon formation
railway_cl	railway	Linear	Railway centreline
region	region	Polygon	Regional Council polygon centroid
region_bdy	p_sufi	Linear	Boundary for Regional Council derived from meshblocks.
road_cl	road_cl	Linear	Road centreline
road_legal	road_legal	Point	Road legality information
road_legal08	road_legal	Point	Maintenance road legality information - Not for client supply
road_segment	road_segment	Polygon	Centroid feature used for road polygon formation
road_seg20	road_segment	Polygon	Centroid feature used for road strata polygon formation
road_inter	road_inter	Polygon	Centroid feature used for road intersection polygon formation
road_inter20	road_inter	Polygon	Centroid feature used for strata road intersection polygon formation
ta	ta	Polygon	Territorial Authority centroid
ta_bdy	p_sufi	Linear	Boundary for Territorial Authority derived from meshblocks.
ward	ward	Polygon	Territorial Authority Ward centroid
ward_bdy	p_sufi	Linear	Boundary for Territorial Authority Ward derived from meshblocks.
walkway_cl	road_cl	Linear	Centreline defining walkways

The relationship between the various features and the networks (or layers) is shown in the following diagram.

Database/Map

Cadastral Layer 100

Networks	Survey 1000	Partition 1002	Centreline 1005	Road Legality 1006
	h_line hyd_segment parcel parcel_arc parcel_bdy parcel_hyd r_line r_r_arc r_r_bdy r_r_hyd rail_segment road_inter road_segment	m_part_bdy parcel02 parcel_arc02 parcel_bdy02 parcel_hyd02 r_r_arc02 r_r_bdy02 r_r_hyd02	access_cl easement_cl pte_road_cl pte_route_cl railway_cl road_cl walkway_cl	r_legal_arc r_legal_bdy road_legal
Networks	Address 1007	Survey Maint 1008	EMF 1009
	address	parcel1008 emf1008 maint_bdy road_legal08	emf

NOTE - The Survey Maint network (1008) is not available for client supply.

District Layer 101

Networks	Land 1011
	land_dist ld_bdy

Strata Layer 102

Networks	Parcel Strata 1020
	parcel20 parcel_arc20 parcel_bdy20 r_line20 r_r_arc20 r_r_bdy20 rail_seg20 road_inter20 road_seg20

Statute Layer 103

Networks	Proclamation 1032
	parcel32 proc_bdy

NOTE - The Proclamation network (1032) is not available for client supply.

Stats/Admin Layer 104

Networks	Meshblock 1040	Ward 1043	TA 1044	Region 1045	Constituency 1046
	mesh_bdy mesh_cad mesh_other mesh_topo meshblock	ward ward_bdy	ta ta_bdy	region region_bdy	constituency constit_bdy
Networks	General 1047	Maori 1048	No Licence 1049
	general general_bdy	maori maori_bdy	no_licence no_lic_bdy

Plan Reference Layer 106

Networks	Plan 1060
	plan plan_prov

3.3. Tables

3.3.1. Primary Tables

The DCDB database schema has 21 user defined primary tables for storing attribute data. Attributes are stored within these tables via user attribute forms associated with certain feature codes, eg. the feature code "road_cl" (road centreline) has the table "road_cl" associated with it.

The user table definitions show the layout of these tables, what columns each table has, what type the column is, the maximum number of characters allowed in each column (size), whether or not a null value is permitted, whether there is an index on the column, if the column contains unique values and the range of feature codes associated with the table.

The emf, land_district and temp_query primary tables are not expanded on in the Data Characteristics manual as they are specific to Land Information NZ internal operations only.

3.3.2. Indirect Tables

Indirect tables contain information not directly associated with a database feature. There are two types of indirect tables - lookup and association. See Appendix 4

The lookup tables are used to resolve data redundancy issues. This means a field need only be entered once but can be accessed via multiple primary tables.

The association tables are used to resolve many to many relationships between primary tables.

There are 5 indirect (2 lookup and 3 association) tables defined within the DCDB database schema - they are:

ROAD_LOOKUP:

Attributes: sufi, created_date, modified_date, road_name, road_type, road_suffix, unofficial flag, asp_location
Description: This lookup table holds entries that would otherwise be replicated in the ADDRESS table, ROAD_CL table and ROAD_SEGMENT table. The only way road names can be entered into the DCDB is via a valid entry in the Authoritative Streets and Places (ASP) database. See Appendix 4.

RD_NAME_SEGMENT:

Attributes: road_lookup sufi and road_segment sufi.
Description: This association table resolves the many to many relationship between the ROAD_LOOKUP table and the ROAD_SEGMENT table. See Appendix 4.

RD_NAME_CL:

Attributes: road_lookup_sufi and road_cl_sufi.
Description: This association table resolves the many to many relationship between the ROAD_CL table and the ROAD_LOOKUP table. See Appendix 4.

ADDRESS_RELATIONS:

Attributes: address_sufi and parcel_sufi.
Description: This association table resolves the many to many relationship between the PARCEL table and the ADDRESS table to allow for multiple addresses. See Appendix 4.

PLAN_LOOKUP:

Attributes: sufi, created_date, modified_date, plan_type, plan_no, plan_suffix, datum, plan_description.
Description: This lookup table holds plan reference entries that would otherwise be replicated in the COVENANT table, PARCEL table and SURV_PLAN table. See Appendix 4.

Back to DCDB Data Characteristics menu