Hi, > Yeah - I think we had better reserve the fourth bit pattern for > something extensible e.g. another byte or several to specify the > actual method, so that we don't have a hard limit of 4 methods.
TWIMC there is an ongoing discussion [1] of making TOAST pointers extendable since this is a dependency for several patches that are currently in development. TL;DR the consensus so far seems to be using varattrib_1b_e.va_tag as a sign of an alternative / extended TOAST pointer content. For the on-disk values va_tag currently stores a constant 18 (VARTAG_ONDISK). Where 18 is sizeof(varatt_external) + /* header size */ 2, which seems to be not extremely useful anyway. If you are interested in the topic please consider joining the thread. [1]: https://postgr.es/m/CAN-LCVMq2X%3Dfhx7KLxfeDyb3P%2BBXuCkHC0g%3D9GF%2BJD4izfVa0Q%40mail.gmail.com -- Best regards, Aleksander Alekseev
