http://apache-carbondata-dev-mailing-list-archive.168.s1.nabble.com/Discussion-Please-vote-and-comment-for-carbon-data-file-format-change-tp2491.html
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