Important Note: This release is being postponed and will go live Monday, November 21, 2022.
PubMed will be moving to an updated version of the E-utilities API on November 15, 2022. As previously announced, this updated version of E-utilities will use the same technology as the web version of PubMed released in 2020. So, search results returned by the updated ESearch E-utility will now match those of the PubMed.gov website.
This update only affects E-utility calls with &db=pubmed. There are no changes to the E-utilities for other databases. You can refer to our previous post or watch our recorded webinar for more details on this update.
Do I need to do anything to prepare?
- If you manage code that creates PubMed E-utility requests, review the changes below to ensure that your code will continue to function after the update.
- Up until launch, you can also verify your code on the public test server.
The test server is available through the following URL:
Test server: https://eutilspreview.ncbi.nlm.nih.gov/entrez/eutils/
To use the test server, replace the standard E-Utilities URL (eutils.ncbi.nlm.nih.gov/entrez/eutils/) in your requests with the URL above.
What will happen to the current version of the PubMed E-utilities after the release?
The current E-utility URLs for PubMed (&db=pubmed) will continue to function after the E-utilities update is released, with only a few exceptions:
- ESearch will only be able to access the first 10,000 records retrieved by the search query (&retmax <= 10,000; &retstart + &retmax <= 10,000).
- EPost will only be able to accept up to 10,000 PMIDs in a single URL request.
- EFetch will no longer support returns in ASN.1 format.
Will the output of PubMed E-utility calls be changing?
Again, in almost all cases, no. Here are the exceptions:
- ESearch will now return exactly the same PubMed IDs (PMIDs) that are currently returned by web PubMed.
- EFetch will now return XML data by default (&retmode is not set) rather than ASN.1. In other words, the default value of &retmode will become “xml”.
How can I keep in touch?
Please write to us if you have any questions or concerns.
You can also follow the NCBI Insights Blog and subscribe to the E-Utilities Announcement Mailing List for updates.