Dear Gurus, I need some solution for a transaction-based system that may have offline clients. Something like CVS in version management, but SQL-based. I need this because we have a team of 6 people, concurrently updating shared XML files and such. When I leave the corporate network I can keep updating corporate data, along with my colleagues. When I join the corporate network again the data will then be published to a common place. I thought about PostgreSQL for several reasons. First of all, concurrent writes while online will not cause confusion. What I need: - If client is online the data should be stored in master DB with data integrity - if client is offline the data should be stored locally - If data is stored locally and client goes online data should be synced to master. - Way of handling conflicting records e.g. client A goes offline, client B modifies master, client A modifies locally, and when goes online again cannot commit the changes. i.e. I need to insert/update (maybe not delete) records even at times when I cannot access the DB (of course, will be committed later). What I DON'T need: - No need for performance (no massive data) - No need for automatic sync (client-initiated sync is sufficient; automatic is a bonus though) - No need to be generic, just some tables should be monitored. Even if I have to write triggers for each table it's OK. - Don't even need master, if it can be solved without master. Crudely speaking I can imagine it something like: - when client goes offline a "snapshot" is present locally, just like at the beginning of a transaction - when client goes online all the changes are "committed" to the master db, just like at end of transaction. The difference is that I do not know when will the client go offline, even client does not know (e.g. ISP goes down) and, of course, there may be a lot of connections while client is offline. Inserting is piece of cake but updates give me a headache. Is there some addon, contrib, whatever for PostgreSQL that can be used for such purpose? Is there some guide how to implement such a system? (my first guess is helper tables, similar in redo logs, but only for specific changes in the database) -- G. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
