>>>>> "Tom" == Tom Lane <t...@sss.pgh.pa.us> writes:
Tom> What amcanbackward is about is whether the index can support Tom> reversing direction mid-scan, as would be required to support Tom> FETCH FORWARD followed by FETCH BACKWARD in a cursor. That's Tom> actually independent of whether the index can implement a defined Tom> ordering; see for example the hash AM, which sets amcanbackward Tom> but not amcanorder. Ugh, so the docs for amutils get this wrong, and if I'd looked at this more carefully when doing them to begin with I'd have given the 'backwards_scan' property a better name or omitted it entirely. I'll fix the docs accordingly. I'm referring specifically to this bit: https://www.postgresql.org/docs/current/static/functions-info.html#FUNCTIONS-INFO-INDEX-PROPS which I think should say "Can the scan direction be changed in mid-scan?" in place of the current text (unless anyone has better wording?) -- Andrew (irc:RhodiumToad)
