so you are doing this for partition elimination? it is a tough call whatever you do
Since userid is unique you can try CLUSTERED BY (userid,datetime,customerid) INTO 256 BUCKETS or try creating a new table based on new column partition and insert/select part of data and see it actually improves performance. I much doubt whichever way you go it is really going to have that impact on your performance. Dr Mich Talebzadeh LinkedIn * https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw <https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw>* http://talebzadehmich.wordpress.com On 6 June 2016 at 08:18, raj hive <raj.hiv...@gmail.com> wrote: > Hi Mich, > > table type is external table. Yes, I am doing this for certain queries > where userid as the most significant column. > > On Mon, Jun 6, 2016 at 12:35 PM, Mich Talebzadeh < > mich.talebza...@gmail.com> wrote: > >> That order datetime/userid/customerId looks more natural to me. >> >> Two questions: >> >> What is the type of table in Hive? >> >> Are you doing this for certain queries where you think userid as the most >> significant column is going to help queries better? >> >> HTH >> >> >> >> Dr Mich Talebzadeh >> >> >> >> LinkedIn * >> https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw >> <https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw>* >> >> >> >> http://talebzadehmich.wordpress.com >> >> >> >> On 6 June 2016 at 04:02, raj hive <raj.hiv...@gmail.com> wrote: >> >>> Hi friends, >>> >>> I have created partitions on hive external tables. partitions on >>> datetime/userid/customerId. >>> >>> now i have to change the order of the partitions for the existing data >>> for all the dates. >>> >>> order of the partition is custerid/userid/datetime. >>> >>> Anyone can help me, how to alter the partitions for the existing table. >>> Need a help to write a script to change the partions on existing data. >>> almost 3 months data is there to modify as per new partition so changing >>> each date is difficult. Any expert can help me. >>> >>> Thanks >>> Raj >>> >> >> >
