How to use the Changeset generator

A step-by-step guide to exporting a changeset from the LINZ Data Service.

Available under the ‘History’ tab of each dataset that supports the Changeset API, the changeset generator allows to you select and export changed data. 

Before you begin, make sure you read through our Changeset API reference documentation (links at end of page).

Timespans 

If you need to keep your copy of LINZ data as up to date as possible and need a track record of all actions that have taken place, we recommend that you access our changesets as regularly as the data is updated, e.g. weekly for property and boundary data.

If you don't always need the latest LINZ data, you can access changesets on a less regular basis by requesting a dataset of the changes that took place spanning multiple revisions.

Changeset exports from the LDS website

Sign in to LDS

The Changeset API uses your API key to generate a WFS request for changeset data. If you haven’t already, sign in to LDS and create an API key.

Dataset revision history

Select the ‘History’ tab for the dataset. The history tab shows you all revisions that have been made to the dataset and sammarises the changes that have occurred between those revisions. As long as the dataset supports changesets you will see change statistics for the number of feature/row additions, modifications and deletions.

Use the checkboxes on the left to select the two revisions you wish to generate a changeset for. 

Selecting a single revision

In the example below we have asked the API to generate a dataset for the changes that occurred between sequential versions of the dataset; from revision 362 to revision 363. In LDS, the FROM timestamp element is exclusive. This means, in effect, we have asked for a changes related to a single revision, those from revision 363.

See our reference guide on dates and timestamps for information about how changeset revisions are managed through timestamps.

If you haven't updated your database in a fortnight or more and need to make sure all data changes are applied to your database, you will need to select revisions that occurred over a greater timespan than a single revision.

Selecting multiple revisions

In this example, the Changeset API will generate a dataset of the changes that took place spanning the five revisions between 7 July 2018 (exclusive) and 18 August 2018 (inclusive).

If multiple changes have been applied to a record over that time, the Changeset API will process these server-side and return to you the latest action for that record.

For example, if a record was inserted at revision 360 then deleted at revision 363, your changeset would only report the DELETE. In addition, if a record was inserted at revision 359, then updated at revisions 360 and 361, your changeset would report this change as an INSERT but with attribute data as at the most recent UPDATE.

See our reference guide on change definition for information on action types.

Access options

Once you’ve selected the two revisions you want to generate a changeset for, the bottom section of the history tab will activate, generating a WFS URL for your requested changeset. 

There are three ways you can access your changeset:

Downloadable file for manual imports or simple data operations

  • Click on the ‘Download’ button to generate a download the changeset in CSV/WKT format

WFS GetCapabilities URL for use in GIS applications

  • Copy the GetCapabilities URL shown in the changeset window and paste it into your GIS client. Your client will read the GetCapabilities document, then fetch the data

WFS GetFeature URL for scripted processes

  • Right click on the ‘Download’ button then copy the GetFeature URL
  • Paste this URL into a text file from which you can alter its syntax, e.g. remove or change the output format, or manually alter the timestamp values. See our reference guide for information on changeset URL syntax.

Keep notified of new revisions

You can track when a new changeset revision for a dataset has been published by subscribing to that dataset’s History feed (found under the History tab for that dataset). This RSS feed will also show you the count of each action type and the total feature count.

Feeds are not available for datasets subject to the LINZ Licence for Personal Data.

Reference Category: Changesets
Reference Tags: RSS feed, Changeset URL, Revision, History
Last Updated: 
2 October 2018