On 2018-Jul-12, Heikki Linnakangas wrote: > > > Thanks for the pointer. My tap test has been covering two out of > > > the three scenarios you have in your script. I have been able to > > > convert the extra as the attached, and I have added as well an > > > extra test with TRUNCATE triggers. So it seems to me that we want > > > to disable the optimization if any type of trigger are defined on > > > the relation copied to as it could be possible that these triggers > > > work on the blocks copied as well, for any BEFORE/AFTER and > > > STATEMENT/ROW triggers. What do you think? > > > > Yeah, this seems like the only sane approach. > > Doesn't have to be a trigger, could be a CHECK constraint, datatype > input function, etc. Admittedly, having a datatype input function that > inserts to the table is worth a "huh?", but I'm feeling very confident > that we can catch all such cases, and some of them might even be > sensible.
A counterexample could be a a JSON compresion scheme that uses a catalog for a dictionary of keys. Hasn't this been described already? Also not completely out of the question for GIS data, I think (Not sure if PostGIS does this already.) -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
