Upgrade to REST API Elasticsearch

Later today (22 September 2025) we will be upgrading Elasticsearch for the REST API. This will happen without any downtime for users and should provide better performance and more accurate query responses.

The database is exactly the same, however in testing we have noticed a few differences in the total-results field for the works endpoint that may be noticeable for a small number of users:

  • Requests containing a query parameter are frequently finding more results than previously. If you track results from the same query over time you might see a jump in the number of responses of up to 0.5%. This isn’t necessarily a reflection of the metadata, but rather an artifact of the upgrade.
  • The filters has-funder and has-funder DOI are picking up about 5% more records than previously. Several other filter results return more results, up to about 0.6% more than previously.
  • The behaviour of the total-results field for the has-update filter has changed: previously it counted the number of relationships but now counts the number of works. This will lead to lower counts, but the same records will be returned by any requests with this filter.

Another difference that you may see is that the results are returned in a different order. If the order is critical for your request you can add a sort parameter, although note that this is resource-heavy and likely to slow down the response time.

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We’ve encountered issues with pagination in the upgraded version: cursors were intermittently not being recognised correctly. We’ve rolled back to the original version while we take a closer look.

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