@Binu Mathew Hey, In my case lot of mappers are launched when I run a select query on ORC file. Also, are there some particular settings of hive to be turned on so that read operations in ORC use ppd. I have tried a lot but almost all my queries read the same as size(of my ORC table), which means reader is reading the whole ORC file. I run Hive 0.13. ... View more

Will usage of DISTRIBUTE BY or SORT BY be helpful? ... View more

@owen My number of mapper and reducers are almost down to half in ORC for a query. bytes read from HDFS is also reduced significantly. But still the time taken by ORC query is almost same as sequence file query. ... View more

Yup @Michael Young. Another way I found was through hadoop fs -text <file-location> On the top of results, INFO compress.CodecPool: Got brand-new decompressor [.snappy] is written which I think is a confirmation that snappy compression is applied. ... View more

I am using Hive 0.13 I didn't try turning on vectorization yet. It was sum of entire column (of a partition in my table). ... View more

Hey, I am pretty much confused which storage format is suited for which type of data. You said "Parquet is well suited for data warehouse kind of solutions where aggregations are required on certain column over a huge set of data.", But I think its true for ORC too. And As @owen said, ORC contains indexes at 3 levels (2 levels in parquet), shouldn't ORC be faster than Parquet for aggregations. ... View more