* Hi Xiaoqiao He*, Please find the *attachment.*
*-Regards* *Kumar Vishal* On Tue, Nov 1, 2016 at 9:27 PM, Xiaoqiao He <xq.he2...@gmail.com> wrote: > Hi Kumar Vishal, > > I couldn't get Fig. of the file format, could you re-upload them? > Thanks. > > Best Regards > > On Tue, Nov 1, 2016 at 7:12 PM, Kumar Vishal <kumarvishal1...@gmail.com> > wrote: > > > > > Hello All, > > > > Improving carbon first time query performance > > > > Reason: > > 1. As file system cache is cleared file reading will make it slower to > > read and cache > > 2. In first time query carbon will have to read the footer from file data > > file to form the btree > > 3. Carbon reading more footer data than its required(data chunk) > > 4. There are lots of random seek is happening in carbon as column > > data(data page, rle, inverted index) are not stored together. > > > > Solution: > > 1. Improve block loading time. This can be done by removing data chunk > > from blockletInfo and storing only offset and length of data chunk > > 2. compress presence meta bitset stored for null values for measure > column > > using snappy > > 3. Store the metadata and data of a column together and read together > this > > reduces random seek and improve IO > > > > For this I am planing to change the carbondata thrift format > > > > *Old format* > > > > > > > > *New format* > > > > > > > > ** > > > > Please vote and comment for this new format change > > > > -Regards > > Kumar Vishal > > > > > > > > >