Performance issue with summary counts in subject table

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Paul Groot

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May 7, 2026, 6:24:41 AM (5 days ago) May 7

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Dear xnat experts,

Our xnat server has a very hard time generating the tables displayed at the project level (such as the subject listing). For some projects with a few thousand subjects and a variety of scans, it took as long as 2 to 3 minutes to load the page. Clicking through to “Next” and “Last” was fast, though. However, for other projects with even slightly higher numbers, the display was extremely fast (max 1 second). What’s interesting is that the slow projects seem to be the ones added most recently. Older projects do not have this issue.

This is our configuration:

XNAT version 1.9.1.1, build: 158 (update pending) in a rootless Podman container
XNAT LDAP Authentication Provider Plugin 1.1.0
XNAT OHIF Viewer Plugin 3.7.0
OS Linux Red Hat 8 running on a very large bare-metal server
PostgreSQL 12.2 (Alpine)
Running since May 2022 (started with version 1.8.x), container file forked from https://github.com/NrgXnat/xnat-docker-compose

Initially, we tried to optimize the PostgreSQL server. We tried virtually all the suggestions available online. Without any effect. Later, we discovered that there is a setting that allows you to disable scan counts via Site administration -> Performance -> Include Summary Counts in Project Data Listings. As soon as we disabled that option, the problem was solved.

What’s striking, of course, is that this issue only occurs in newer projects. For now, this is our workaround, but we’d still like to display the scan counts in the overview. Does anyone have suggestions to solve this?