On Mon, Aug 24, 2020 at 3:35 PM Andres Freund <and...@anarazel.de> wrote: > To avoid unnecessary backward compat pains it seems best to first > introduce compat wrappers using the current signature, and then > subsequently replace in-core callers with the direct calls.
I like the idea of doing this, purely to make profiler output easier to interpret. Passing a shared-or-exclusive flag is kind of a natural thing to do within code like _bt_search(), where we sometimes want to exclusive-lock the leaf level page but not the internal pages that we descend through first. Fortunately we can handle the flag inside the existing nbtree wrapper functions quite easily -- the recently added _bt_lockbuf() can test the flag directly. We already have nbtree-private flags (BT_READ and BT_WRITE) that we can continue to use after the old interface is fully deprecated. More generally, it probably is kind of natural to have a flag like BUFFER_LOCK_SHARE/BUFFER_LOCK_EXCLUSIVE (though not like BUFFER_LOCK_UNLOCK) within index access methods. But I think that there are several good reasons to add something equivalent to _bt_lockbuf() to all index access methods. -- Peter Geoghegan
