The primary supply mechanism of AddressBase Premium data is referred to as non-geographic chunks. This is a way of dividing up the data into chunks that are supplied in separate volumes, which have a fixed maximum amount of records. The supply is not supplied with any reference to the geographic position of records.
Public Sector Geospatial Agreement (PSGA) customers are able to order geographic chunks (5km tiles) as well as non-geographic chunks, although geographic chunks are not considered the main form of supply.
All customers are also able to take a complete supply (referred to as a Managed Great Britain Set: MGBS) or an area of interest (AOI) as a full supply or change-only update (COU) supply.
The filename for non-geographic chunks is constructed as follows:
ProductName_supply_ccyy-mm-dd_vvv.format:
ProductName: AddressBasePremium
supply: FULL or COU
ccyy-mm-dd: the date the file was generated
vvv: the volume number of the file
format: the format of the files, for example, csv, gmlor gpkg
For example:
AddressBasePremium_FULL_2013-05-28_001.gml (GML full supply)
AddressBasePremium_FULL_2013-05-28_001.gpkg (GeoPackage full supply)
AddressBasePremium_COU_2013-05-28_001.csv (CSV COU supply)
A file size limit might be imposed by the file system to which the file is written.
If the data has been provided in a ZIP file, the filename is constructed as follows:
productName_supply_ccyy-mm-dd_vvv_format.zip
For example:
AddressBasePremium_FULL_2013-05-28_001_gml.zip (GML full supply zipped)
If you receive your data as geographic chunks (PSGA customers only), the filename for geographic chunks (PSGA customers only) is constructed as follows:
ngxxyy.format
ngxxyy: The four-digit grid reference belonging to the 1 km south-west corner of the 5 km chunk.
format: The format of the files received, for example, csv or gml.
For example:
NC4040.gml (GML geographic supply)
NC4040.csv (CSV geographic supply)
When you receive your geo-chunked download data for GKPG, you will see a single folder on opening the data.
For example:
AddressBasePremium_FULL_2013-05-28_001_gpkg (GPKG full supply)
If the data has been provided in a ZIP file, the following file naming convention will be used for CSV and GML:
ngxxyy.zip
For example:
NC4040.zip (geographic supply zipped)
For GeoPackage supply, you will see a single zipped folder on downloading the data. For example:
AddressBasePremium_FULL_2013-05-28_001_gpkg.zip (GeoPackage full supply)
AddressBase Premium is available as a change-only update (COU) supply for CSV and GML formats. COU supplies are not available for GPKG format.
A COU supply of data contains records or files that have changed between product refresh cycles. The primary benefit in supplying data in this way is that data volumes are smaller, reducing the amount of data that requires processing when compared to a full supply.
COU data enables a user to identify three types of change:
Deletes (CHANGE_TYPE ‘D’) are objects that have ceased to exist in your areas of interest (AOI) since the last product refresh.
Inserts (CHANGE_TYPE ‘I’) are objects that have been newly inserted into your AOI since the last product refresh.
Updates (CHANGE_TYPE ‘U’) are objects that have been updated in your AOI since the last product refresh.
A COU file for non-geographic chunked data can be identified by its naming convention as highlighted above. Any change record will be provided as a full record with the appropriate change type, as listed above.
A geographic chunked COU is not supplied as per the non-geographic chunked COU outlined above. Its file naming convention can be found above. If a single record has changed within a specified 5km tile, the entire 5km tile containing all features will be supplied. This means the user will need to remove all features that previously existed in the provided tile(s) and insert the entire new tile(s) in its place.
When users are deleting, inserting or updating features, it is up to the user to consider their archiving requirements. If deleted records are important to your business requirements, you must take appropriate action to archive previous records.