The proposed change is reasonable, +1. But is there a plan to make the reader backward compatible with the old format? So the impact to the current deployment is minimum.
Regards, Jacky > 在 2016年11月2日，上午12:38，Kumar Vishal <kumarvishal1...@gmail.com> 写道： > > 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 > <mailto: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 > <mailto: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 > > > > > > > > >
