Kindly provide an example where one can see EXPLAIN SELECT .....shows external index usage? That will be great. Choose your table and block size
Thanks 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 21 April 2016 at 12:34, Jörn Franke <jornfra...@gmail.com> wrote: > I am still not sure why you think they are not used. The main issue is > that the block size is usually very large (eg 256 MB compared to kilobytes > / sometimes few megabytes in traditional databases) and the indexes refer > to blocks. This makes it less likely that you can leverage it for small > datasets in the area of GBs, they make more sense for TB, PB, except if you > reduce the blocksize. However, given ORC, the traditional indexes make > probably less sense. I tried to give an overview here: > https://t.co/DtkjKWOM7G > However comments to improve it are very welcome. > > > > Sent from my iPhone > On 21 Apr 2016, at 12:02, Mich Talebzadeh <mich.talebza...@gmail.com> > wrote: > > > Hi, > > As we have discussed this few times, Hive external indexes (as opposed to > Store Indexes in ORC tables) are there but are not currently utilised. > > For Hive to be effective it needs to use these indexes for a variety of > reasons and the CBO should leverage these indexes. > > I am not sure how far we are down the road with Work In Progress on this. > However, I am happy to help with this. > > 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 > > > >
