On Sat, Mar 25, 2017 at 11:24 PM, Pavan Deolasee <pavan.deola...@gmail.com> wrote: > > On Sat, 25 Mar 2017 at 11:03 PM, Peter Geoghegan <p...@bowt.ie> wrote: >> >> On Sat, Mar 25, 2017 at 12:54 AM, Amit Kapila <amit.kapil...@gmail.com> >> wrote: >> > I am not sure how do you want to binary compare two datums, if you are >> > thinking datumIsEqual(), that won't work. I think you need to use >> > datatype specific compare function something like what we do in >> > _bt_compare(). >> >> How will that interact with types like numeric, that have display >> scale or similar? >> > I wonder why Amit thinks that datumIsEqual won't work once we convert the > heap values to index tuple and then fetch using index_get_attr. After all > that's how the current index tuple was constructed when it was inserted.
I think for toasted values you need to detoast before comparison and it seems datamIsEqual won't do that job. Am I missing something which makes you think that datumIsEqual will work in this context. > In > fact, we must not rely on _bt_compare because that might return "false > positive" even for two different heap binary values (I think). I am not telling to rely on _bt_compare, what I was trying to hint at it was that I think we might need to use some column type specific information for comparison. I am not sure at this stage what is the best way to deal with this problem without incurring non trivial cost. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
