On Mon, 26 Apr 2021 at 15:55, Tom Lane <t...@sss.pgh.pa.us> wrote: > > I checked into the commit history (how'd we ever survive without "git > blame"?) and found that my argument above is actually wrong in detail. > Before cab5dc5da of 2013-10-18, rewriteTargetListIU expanded non-updated > columns for all views not only trigger-updatable ones. However, that > behavior itself goes back only to 2ec993a7c of 2010-10-10, which added > triggers on views; before that there was indeed no such expansion.
Ah, that makes sense. Before cab5dc5da, expanding non-updated columns of auto-updatable views was safe because until then a view was only auto-updatable if all it's columns were. It was still unnecessary work though, and with 20/20 hindsight, when triggers on views were first added in 2ec993a7c, it probably should have only expanded the targetlist for trigger-updatable views. > Of course the view rewrite mechanisms are ten or so years older than > that, so the conclusion that they weren't designed to need this still > stands. Yeah, I think that conclusion is right. The trickiest part I found was deciding whether any product queries from conditional rules would do the right thing if the main trigger-updatable query no longer expands its targetlist. But I think that has to be OK, because even before trigger-updatable views were added, it was possible to have product queries from conditional rules together with an unconditional do-nothing rule, so the product queries don't rely on the expanded targetlist, and never have. Regards, Dean
