On Wed, Dec 4, 2013 at 5:28 PM, Peter Geoghegan <p...@heroku.com> wrote: > I'm also curious about the impact on insertion into primary key > indexes. Presently, we hold an exclusive buffer lock for the duration > of a couple of operations when checkUnique != UNIQUE_CHECK_NO. > _bt_binsrch() is one such operation. The other one there, > _bt_check_unique(), is likely to be a lot cheaper than _bt_binsrch() > on average, I think, so I'm cautiously optimistic that it'll be > noticeable. I better go and check it out.
Depending on how well this goes, I might also teach _bt_doinsert() to hint to _bt_binsrch() (or as I'm calling it, _bt_page_search()) that it should look to the end of the page when searching, using a similar mechanism to the mechanism for hinting that the main Datum-compare optimization is applicable (this strategy would be abandoned if it didn't work immediately - as soon as the last item on the page turned out to be greater than or equal to the scankey value). This is something that I think would help with SERIAL columns, where it's possible in principle to pass that kind of insight around -- if you can live with making SERIAL more than mere syntactic sugar. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
