* Tom Lane (t...@sss.pgh.pa.us) wrote: > Alvaro Herrera <alvhe...@2ndquadrant.com> writes: > >> I had considered removing those but thought that some users might think > >> that they're only "altering" one table and therefore felt it made sense > >> to keep those explicitly listed. > > > I agree with Stephen; it's not crystal clear from the user's POV that > > the command is altering two tables. It's worth mentioning this > > explicitly; otherwise this is just a documented gotcha. > > Well, it already is shown explicitly in the syntax summary. The text > is simply trying to restate that in an easily remembered fashion, and > the more exceptions, the harder it is to remember. You might as well > forget trying to provide a rule at all and just say something like > "Most forms of ALTER TABLE can be combined, except as shown in the > syntax diagram."
I do wonder if perhaps we should change 'action' to something like 'combinable_action' or something more explicit which we could easily refer to later in a statement along the lines of: Multiple combinable_actions specified in a single ALTER TABLE statement will be applied together in a single pass over the table. > (Of course, maybe the question we ought to be asking here is why > ATTACH/DETACH PARTITION failed to go with the flow and be a > combinable action.) I did wonder that myself but havne't looked at the code. I'm guessing there's a reason it's that way. Thanks! Stephen
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