On Wed, Aug 4, 2010 at 12:15 PM, lei liu <liulei...@gmail.com> wrote: > Hello Edward Capriolo, > > Thank you for your reply. Are you sure that if you string enough 'or' > together (say 8000) the query parser which uses java beans serialization > will OOM? How many memory you assign to hive? > > 2010/8/4 Edward Capriolo <edlinuxg...@gmail.com> >> >> On Wed, Aug 4, 2010 at 6:10 AM, lei liu <liulei...@gmail.com> wrote: >> > Because my company reuire we use 0.4.1 version, the version don't >> > support IN >> > clause. I want to use the OR clause(example:where id=1 or id=2 or id=3) >> > to >> > implement the IN clause(example: id in(1,2,3) ). I know it will be >> > slower >> > especially when the list after "in" is very long. Could anybody can >> > tell me >> > why is slow when use OR clause to implement In clause? >> > >> > >> > Thanks, >> > >> > >> > LiuLei >> > >> >> I can not imagine the performance difference between 'or' or 'in' >> would be that great but I never benchmarked it. The big looming >> problems is that if you string enough 'or' together (say 8000) the >> query parser which uses java beans serialization will OOM. >> >> Edward > >
That is exactly what I am saying. I tested with 4GB and 8GB. I am not exactly sure how many OR's you can get away with for your memory size, but some upper limit exists currently. Most people never hit it. (I did because my middle name is "edge case" )
