2013/11/8 Tom Lane <t...@sss.pgh.pa.us>: > Albe Laurenz <laurenz.a...@wien.gv.at> writes: >> What I would like to do is add a custom resjunk column >> (e.g. a bytea) in AddForeignUpdateTargets that carries a row identifier >> from the scan state to the modify state. >> Would that be possible? Can I have anything else than a Var >> in a resjunk column? > > [ thinks for awhile... ] Hm. In principle you can put any expression > you want into the tlist during AddForeignUpdateTargets. However, if it's > not a Var then the planner won't understand that it's something that needs > to be supplied by the table scan, so things won't work right in any but > the most trivial cases (maybe not even then :-(). > > What I'd try is creating a Var that has the attno of ctid > (ie, SelfItemPointerAttributeNumber) but the datatype you want, ie bytea. > This won't match what the catalogs say your table's ctid is, but I think > that nothing will care much about that.
Apologies for reinvigorating this thread, but I'm running into a similar wall myself and would like to clarify if this approach will work at all. My foreign data source is returning a fixed-length string as a unique row identifier; in AddForeignUpdateTargets() I can create a Var like this: var = makeVar(parsetree->resultRelation, SelfItemPointerAttributeNumber, BPCHAROID, 32, InvalidOid, 0); but is it possible to store something other than a TIDOID here, and if so how? Regards Ian Barwick -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
