On Tue, Jan 20, 2015 at 7:07 PM, Peter Geoghegan <p...@heroku.com> wrote: > On Tue, Jan 20, 2015 at 3:57 PM, Peter Geoghegan <p...@heroku.com> wrote: >> It's certainly possible to fix Andrew's test case with the attached. >> I'm not sure that that's the appropriate fix, though: there is >> probably a case to be made for not bothering with abbreviation once >> we've read tuples in for the final merge run. More likely, the >> strongest case is for storing the abbreviated keys on disk too, and >> reading those back. > > Maybe not, though: An extra 8 bytes per tuple on disk is not free. > OTOH, if we're I/O bound on the final merge, as we ought to be, then > recomputing the abbreviated keys could make sense, since there may > well be an idle CPU core anyway.
I was assuming we were going to fix this by undoing the abbreviation (as in the abort case) when we spill to disk, and not bothering with it thereafter. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
