On Nov 1, 2011, at 7:23 AM, Paul wrote: > What's the cleanest way to perform a multiple insert or update? ie, if the > record > already exists an update operation is performed or if not an insert is > performed.
that's a funny usage of terminology - a "multiple" insert would normally be construed as meaning an INSERT that has many rows at once, which is a different issue. As I read this I wasn't clear what you were asking for, the "MERGE" SQL construct, or just asking about ORM merge. After I wrote a whole reply here based on the SQL construct I realized you were talking about the ORM. If you have a bunch of objects, all of which you can populate with their primary key, and you'd like some to result in INSERTS and others in UPDATE, then yes you can use Session.merge() in a loop. I would try to pre-load all the existing rows, if possible, into a temporary collection - ideally limited to those rows you know you're operating upon. That would make the operation of Session.merge() much faster as it can locate each object in the local identity map rather than emitting a SELECT for each one. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
