GitHub user manishgupta88 opened a pull request: https://github.com/apache/carbondata/pull/2191
[WIP] Improve compaction performance Problem: Compaction performance is slow as compared to data load Analysis: 1. During compaction result filling is done in row format. Due to this as the number of columns increases the dimension and measure data filling time increases. This happens because in row filling we are not able to take advantage of OS cacheable buffers as we continuously read data for next column. 2. As compaction uses a page level reader flow wherein both IO and uncompression is done at page level, the IO and uncompression time increases in this model. Solution: 1. Implement a columnar format filling data structure for compaction process for filling dimension and measure data. 2. Perform IO at blocklet level and uncompression at page level. **Note:** **This PR contains the solution for point 1** - [ ] Any interfaces changed? No - [ ] Any backward compatibility impacted? No - [ ] Document update required? No - [ ] Testing done Manually verified - [ ] For large changes, please consider breaking it into sub-tasks under an umbrella JIRA. NA You can merge this pull request into a Git repository by running: $ git pull https://github.com/manishgupta88/carbondata compaction_columnar_result_filling Alternatively you can review and apply these changes as the patch at: https://github.com/apache/carbondata/pull/2191.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #2191 ---- commit a27928e81621cfa1acb72f6545f222d55c02c3f4 Author: m00258959 <manish.gupta@...> Date: 2018-04-13T14:45:40Z Problem: Compaction performance is slow as compared to data load Analysis: 1. During compaction result filling is done in row format. Due to this as the number of columns increases the dimension and measure data filling time increases. This happens because in row filling we are not able to take advantage of OS cacheable buffers as we continuously read data for next column. 2. As compaction uses a page level reader flow wherein both IO and uncompression is done at page level, the IO and uncompression time increases in this model. Solution: 1. Implement a columnar format filling data structure for compaction process for filling dimension and measure data. 2. Perform IO at blocklet level and uncompression at page level. ---- ---