Hi Flavio, You'll need to add a secondary index to SOMEFIELD (or SOMEFIELD + VALID) to speed that up. You can write it more simply as SELECT COUNT(DISTINCT SOMEFIELD) FROM TEST.MYTABLE WHERE VALID AND SOMEFIELD IS NOT NULL.
Otherwise, you'll end up doing a full table scan (and use a fair amount of memory depending on the cardinality of SOMEFIELD). The above with a secondary index would skip to the distinct values instead. Thanks, James On Fri, Mar 16, 2018 at 8:30 AM, Flavio Pompermaier <pomperma...@okkam.it> wrote: > Hi to all, > I'm running a query like this one on my Phoenix 4.13 (on CDH 5.11.2): > > SELECT COUNT(*) FROM ( > SELECT DISTINCT(SOMEFIELD) > FROM TEST.MYTABLE > WHERE VALID = TRUE AND SOMEFIELD IS NOT NULL > ) > > Unfortunately the query timeouts (timeout is 10 min).... Any suggestion > about how to tune my installation? > > Best, > Flavi >
