Re: BUG #17513: recompressing already-compressed data via VACUUM FULL or CLUSTER does not work

The described behavior didn't even make it into 14.0; and I have no clue where such a thing would be documented to guess if the lack was intentional or not.  I can confirm that as of today the behavior in HEAD is to not decompress and recompress during rewrite.  Frankly, this seems like the expected behavior absent any documentation to the contrary.  Whether there is a use case for someone to code up a way to get a recompression to happen is another matter.  Oddly, I kinda expected that "update cmdata set f1 = f1;" might do it but alas it does not (...set f1 = f1 || ''... works; I'm not quite sure how much worse that, immediately followed by vacuum full, would be compared to whatever it would take to do it all during the full vacuum...especially if one is changing every single row on the table).