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.
Hello, now that you’re only returning results as XML by default, can you look into publishing XSD schemas of the XML, instead of DTDs?
Thank you for your feedback. I’ll pass your suggestions along to the PubMed team.
Has EDirect been updated yet to provide a workaround for the new 10k limit in the E-Utilities?
Yes, EDirect does have the workaround for the 10K limit. You currently need to run:
export EDIRECT_PREVIEW=true
This will be the case until the new API is the default for PubMed.