* 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
> >
> >
> >
> >
>

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