inserting null for any column will generate the tombstone (and you can't have null for clustering column, except case when it's an empty partition with static column). if you're really inserting the new data, not overwriting existing one - use UNSET instead of null
On Fri, Aug 21, 2020 at 10:45 AM Attila Wind <attilaw@swf.technology> wrote: > Thanks a lot! I will process every pointers you gave - appreciated! > > 1. we do have collection column in that table but that is (we have only 1 > column) a frozen Map - so I guess "Tombstones are also implicitly created > any time you insert or update a row which has an (unfrozen) collection > column: list<>, map<> or set<>. This has to be done in order to ensure the > new write replaces any existing collection entries." does not really apply > here > > 2. "Isn’t it so that explicitly setting a column to NULL also result in a > tombstone" > Is this true for all columns? or just clustering key cols? > Because if for all cols (which would make sense maybe to me more) then we > found the possible reason.. :-) > As we do have an Integer coulmn there which is actually NULL often (and so > far in all cases) > > > Attila Wind > > http://www.linkedin.com/in/attilaw > Mobile: +49 176 43556932 > > > 21.08.2020 09:49 keltezéssel, Oleksandr Shulgin írta: > > On Fri, Aug 21, 2020 at 9:43 AM Tobias Eriksson < > tobias.eriks...@qvantel.com> wrote: > >> Isn’t it so that explicitly setting a column to NULL also result in a >> tombstone >> > > True, thanks for pointing that out! > > Then as mentioned the use of list,set,map can also result in tombstones >> >> See >> https://www.instaclustr.com/cassandra-collections-hidden-tombstones-and-how-to-avoid-them/ >> > > And A. Ott has already mentioned both these possible reasons :-) > > -- > Alex > > -- With best wishes, Alex Ott http://alexott.net/ Twitter: alexott_en (English), alexott (Russian)
