Hi, I'm hitting the default (100) `max_connection` PostgreSQL limit with ~4 users using a QGIS project with ~25 layers/tables. I know that I can raise the limit, but I'm trying to understand how QGIS handles database connections.
I didn't find so much information about it: 1. https://lists.osgeo.org/pipermail/qgis-developer/2008-March/003446.html. Old post against, something like, an internal connection pool in QGIS 2. https://github.com/qgis/QGIS/issues/30373. Feature request to share a single connection between different layers 3. https://stackoverflow.com/a/71557537/930271 an ¿explanation? of how connection works in QGIS. I copy&paste here because this post may be hide for some users: for what I know every single layer creates at least one, possibly two, > connections (one is read only the other one is read-write ), these two > connections have the same lifetime of the layer, the read-write connection > is created on-demand if a read-write operation is requested > (editing/adding/deleting features). Multiple layers using the same DB connection will not share these two > connections. In addition to the two connections above, temporary connections are created > from a connection pool when the features are fetched from the layer(s), > these connections are pooled (shared) and released when the fetching is > finished, there is also a timeout to close them after 60 seconds idle. It would be useful to check PG logs and see in which state these > connections are, from my tests, the read-only connection is kept in > ClientRead | idle. So, - Can someone confirm the previous quote, explain how QGIS handles connections, or point me to relevant code or doc? - An invisible/unchecked layer consumes a connection? - Does make sense a feature request about this topic. Maybe - Reuse connection - a kind of internal pooling - a configurable user limit, so next database access will wait for other connections to close to start operations - ... Many thanks. -- Francisco Puga iCarto | Innovación, Cooperación, Cartografía y Territorio S.L. https://icarto.es
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