On Wed, Mar 29, 2017 at 11:52 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > 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. >
Another related, index_form_tuple() has a check for VARATT_IS_EXTERNAL not VARATT_IS_EXTENDED, so may be that is cause of confusion for you, but as I mentioned even if you change the check heap_tuple_fetch_attr won't suffice the need. -- 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