System Category	Addressing
Source	Corporate Land & Property Gazetteer
Available since	2010
Organisation

Overview

Astun have written the NLPG (National Land & Property Gazetteer) Importer to import NLPG csv files which are eventually converted to SQL records. The NLPG Importer allows for the importing of NLPG supplied files in DTF 7.3 format which may then be used in iShare as an address lookup. As iShare will only be performing an address lookup (with property easting and northing) we only need to process the STREET (11), STREET DESCRIPTOR (15), BLPU (21) and LPI (24) records.

As well as importing new files supplied by the NLPG, either Full or COU, the NLPG Importer has a “Refresh all / Reset” function where the whole history is loaded in and the scripts work off the age of the files.

When the NLPG Importer runs a log file will be written to the Logs sub folder where the Python script resides e.g. C:\Python\NLPG Importer\Logs.

The Import Process

In order to import your NLPG data into Data Share and keep it up-to-date you will need to do the following:

Process the NLPG data files

Files received from the NLPG hub will be copied, by the customer, into a processing folder (Pending) and an archive folder (Archive). The importer will then process each file in order of datestamp (oldest first). Once a file has been successfully processed it will be placed into a Completed folder.

The NLPG Importer will iterate through the file line by line and will copy the contents of the line into one of four separate csv files.

This will be done for the following record types:

REC_ID	Description
11	Street
15	Street Descriptor
21	BLPU
24	LPI

Once the file processing has finished, the importer will then attempt to copy the files into their respective tables using the Postgres 'COPY INTO' command. Each imported row will be given its own sequence number column in the database table. There will be four tables created, one for each of the record identifiers above. For details of the database view please see National Land & Property Gazetteer (NLPG).

Import them into Data Share

A View of the latest data will be created in the NLPG Importer database for each of the four tables.

The view for each table will be created by selecting the records with the highest sequence number per Unique Identifier. If the change type is deleted, then the record will not be included in the view.

The Unique Identifiers for each record type are as follows:-

Record Type	Unique Identifier Field(s)
Street (11)	USRN
Street Descriptor (15)	USRN+LANGUAGE
BLPU (21)	UPRN
LPI (24)	LPI_KEY

A Data Share connection to each of the four views in the NLPG Postgres database will need to be created in iShare Studio.

Automate the NLPG Import process

In order to automate the NLPG Import process a Workflow Job will need to be created along with several Tasks. Once the Job has been defined you can schedule the Job to run at a particular time.

Please see the NLPG Importer Installation & Configuration topic for details.

If there is a problem with the import, it will be possible to restart the import again, starting from the first file received using the Archive folder. The process will be as follows:-

All records are deleted from each of the four tables
All files in the Pending folder will be deleted
All files are copied from the Archive folder to the Pending folder

The process will then continue as normal until all files have been processed.

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