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After considering a few options, I'm trying to give my 15-20 QGIS 2.2 users the ability to concurrently view/edit one or two basic point PostGIS layers, largest one has just 16,000 records. I've installed PostgreSQL 9.1 / PostGIS 2.0 and basic testing seems to work ok but haven't unleashed it to the masses yet.

We'll typically only have 2-3 editors at a time, but possibly 15 viewers. Edits will all be in QGIS, viewers will be QGIS and ArcGIS (but we don't have SDE).

As I said, these are just basic point files, and edits will just be adding/deleting points and some table edits. I am not worried about editing the same features at the same time.

Can the combination provide dependable multi-user editing for two basic point files?

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Since you're not worried about simultaneous edits on features, I'd say that in theory you have nothing to worry about. The main danger w/ QGIS is that simultaneous editors can stomp on each other's edits without noticing ("last edit wins").

For data under active editing with multiple users you might want to at least keep track of history, which you can do w/o changing anything about QGIS, just adding some triggers and a history table to your active tables.

http://postgis.net/workshops/postgis-intro/history_tracking.html

That way if you ever want to revert changes you'll have a place to go that's easier to access than the database backups and point-in-time recovery.

  • Thanks for your reply @Paul, seems like concurrent PostGIS multi-user editing via QGIS is safe for making table updates and moving existing points around. My main concern is with INSERTS and DELETES. If two users have open editing sessions going, User A adds a point and User B deletes a point. User A saves first. When User B saves, will User A's point be removed since it wasn't part of the DB when User B started editing? I'm going to do some testing today, but that's my main concern (losing edits). – mike Sep 28 '14 at 18:30
  • Do test, but my understanding of QGIS editing is that it's feature by feature, so it will only be saving the particular actions of the user, not the entire state of their view of the data, when they hit save. So in your example A's point will be added and B's deleted, just as you would like. – Paul Ramsey Sep 29 '14 at 4:14
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    Spent a few hours testing today. You're right, it does just what I hoped. Only thing to watch is when a user deletes a record and saves, it's gone, regardless of other users' open sessions. Thanks for your help @Paul! Now I have to get that history tracking set up..... – mike Sep 29 '14 at 4:26

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