"Jim C. Nasby" <jnasby@xxxxxxxxxxxxx> writes: > I'd actually been thinking about this recently, and had come up with the > following half-baked ideas: > Allow a transaction to specify exactly what tables it will be touching, > perhaps as an extension to BEGIN. Should any action that transaction > takes attempt to access a table not specified, throw an error. > A possible variant on that would be to automatically determine at > transaction start all the tables that would be accessed by that > transaction. > Once that list is available, vacuum should be able to use it to ignore > any transactions that have promised not to touch whatever table it's > vacuuming. No, you missed my point entirely. The above would help not at all, unless the restrictions were somehow propagated through XMIN calculations, which seems impracticable. (Every backend calculate a separate XMIN with respect to every table that's being mentioned by any other backend? I don't think so...) regards, tom lane
