PostgreSQL performances issue

[tflorac]

Hi,
I have a kind of content management application based on the Pyramid framework and using PostgreSQL+RelStorage which is used to store many documents (actually 2 millions). A large set of documents properties are indexed into a large Hypatia catalog. The PostgreSQL database (using PostgreSQL 13) is using settings as defined in RelStorage documentation.
An external batch process is sometimes used to upload documents using a REST API. I noticed that when I start both the application and the database the performances are OK, but after a while PostgreSQL CPU usage is increasing and requests throughput is decreasing drastically! Restarting the application (without restarting PostgreSQL) is helping to restore performances for a while, but not for a very long time... :/
Any idea about the origin of this behaviour?
Best regards,
Thierry

[tflorac]

Here is a graph of application latency, showing application restarts: