Hi, I have the following table in Hive Posts(Id, UserId, PostDate, ...) CLUSTERED BY (UserId) SORTED BY (PostDate) INTO 256 BUCKETS;
Since the data is hash partitioned based on the 'UserId' column, buckets were created based on the hash value of 'UserId'. Now, when I issue a Select query to fetch all the posts by a particular 'UserId ' (say, Select count(Id) from Posts where UserId=1), does it scan only the bucket to which 'UserId' is hashed to?. But, when I run this query, I could see all the buckets being searched for the UserId. Moreover, I see that's there is a way to sample the table based on the buckets. Why can't hive automatically figure out the bucket to which UserId is hashed to and search only in that bucket? Can someone clarify me on this? Thanks, Deepak
