Check the index creation has NULLS FIRST (or LAST) on both indexes that are used. Use explain to see what indexes are used
See docs for create index: https://www.postgresql.org/docs/current/sql-createindex.html On Thu, May 11, 2023, 7:30 AM Marc Millas <marc.mil...@mokadb.com> wrote: > Hi, > > I keep on investigating on the "death postgres" subject > but open a new thread as I don't know if it's related to my pb. > > I have 2 different clusters, on 2 different machines, one is prod, the > second test. > Same data volumes. > > On prod if I do > select col_a, count(col_a) from table_a group by col_a order by col_a > desc, > I get the numbers of NULL on top. > To get the number of NULL on top on the test db, I have to > select col_a, count(col_a) from table_a group by col_a order by col_a asc. > > so, it looks like there is something different within the b-tree operator > class of varchar (?!?) > between those 2 clusters. > > What can I check to to explain this difference as, to my understanding, > it's not a postgresql.conf parameter. > > thanks > > Marc MILLAS > Senior Architect > +33607850334 > www.mokadb.com > >
