TOAST - moving Compression into Toast for oversized Tuples

Hi hackers,
Along with major TOAST improvement with Pluggable TOAST we see the really
important smaller one - moving compression functionality when dealing with
oversized Tuples into Toast, because Toast is meant to deal with how
oversized Tuple is stored and it is logical to make it responsible for
compression too.
Currently it is done in heap_toast_insert_or_update() (file heaptoast.c)
before the attribute is TOASTed, we suggest the TOAST should decide if the
attribute must be compressed before stored externally or not for . Also, it
allows us to make Toasters completely responsible for TOASTed data storage
- how and where these data are stored.
Any advice or suggestion would be welcome.

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Best regards,
Nikita Malakhov.