On Tue, Mar 28, 2017 at 10:35 PM, Pavan Deolasee <pavan.deola...@gmail.com> wrote: > > On Tue, Mar 28, 2017 at 7:04 PM, Amit Kapila <amit.kapil...@gmail.com> > wrote: >> >> >> >> For such an heap insert, we will pass >> the actual value of column to index_form_tuple during index insert. >> However during recheck when we fetch the value of c2 from heap tuple >> and pass it index tuple, the value is already in compressed form and >> index_form_tuple might again try to compress it because the size will >> still be greater than TOAST_INDEX_TARGET and if it does so, it might >> make recheck fail. >> > > Would it? I thought "if > (!VARATT_IS_EXTENDED(DatumGetPointer(untoasted_values[i]))" check should > prevent that. But I could be reading those macros wrong. They are probably > heavily uncommented and it's not clear what each of those VARATT_* macro do. >
That won't handle the case where it is simply compressed. You need check like VARATT_IS_COMPRESSED to take care of compressed heap tuples, but then also it won't work because heap_tuple_fetch_attr() doesn't handle compressed tuples. You need to use heap_tuple_untoast_attr() to handle the compressed case. Also, we probably need to handle other type of var attrs. Now, If we want to do all of that index_form_tuple() might not be the right place, we probably want to handle it in caller or provide an alternate API. -- 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
