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apache / carbondata / 9da42c495e84deb74c277e182e2e4b93bca8c129
commit9da42c495e84deb74c277e182e2e4b93bca8c129[log] [tgz]
authorManhua <kevinjmh@qq.com>Wed Jun 24 16:53:28 2020 +0800
committerQiangCai <qiangcai@qq.com>Tue Jun 30 10:17:53 2020 +0800
tree0cddd30d1a64438004a4b4b0d1707673ac929a7c
parent3908209b693e5bb04c18ca62324388727899d323 [diff]
[CARBONDATA-3871] Optimize performance when getting row from heap

Why is this PR needed?
Currently carbon uses priority queue to sort holders of sorted rows.
It first polls a holder from the heap, and adds it back if holder is not empty.
This will cause two times heap maintainance. We can reduce half of that operation,
and test shows it can save one third of time to get rows .

What changes were proposed in this PR?
What will be done when poll item from priority queue currently is:
1. remove first item.
2. move the last item to the position of first item, siftDown the new first item.
In this patch, we will peek(without removing from heap) the first item and get a row,
and siftDown the holder to a proper position if the holder is not empty.
Since this will affect order of non-sorted columns, it depends on #3813

Does this PR introduce any user interface change?
No

Is any new testcase added?
No

This closes #3804
7 files changed
tree: 0cddd30d1a64438004a4b4b0d1707673ac929a7c
  1. .github/
  2. assembly/
  3. bin/
  4. build/
  5. common/
  6. conf/
  7. core/
  8. dev/
  9. docs/
  10. examples/
  11. format/
  12. geo/
  13. hadoop/
  14. index/
  15. integration/
  16. licenses-binary/
  17. mv/
  18. processing/
  19. python/
  20. sdk/
  21. streaming/
  22. tools/
  23. .gitignore
  24. LICENSE
  25. NOTICE
  26. pom.xml
  27. README.md
README.md

Apache CarbonData is an indexed columnar data store solution for fast analytics on big data platform, e.g.Apache Hadoop, Apache Spark, etc.

You can find the latest CarbonData document and learn more at: http://carbondata.apache.org

CarbonData cwiki

Visit count: HitCount

Status

Spark2.4: Build Status Coverage Status

Features

CarbonData file format is a columnar store in HDFS, it has many features that a modern columnar format has, such as splittable, compression schema ,complex data type etc, and CarbonData has following unique features:

  • Stores data along with index: it can significantly accelerate query performance and reduces the I/O scans and CPU resources, where there are filters in the query. CarbonData index consists of multiple level of indices, a processing framework can leverage this index to reduce the task it needs to schedule and process, and it can also do skip scan in more finer grain unit (called blocklet) in task side scanning instead of scanning the whole file.
  • Operable encoded data :Through supporting efficient compression and global encoding schemes, can query on compressed/encoded data, the data can be converted just before returning the results to the users, which is “late materialized”.
  • Supports for various use cases with one single Data format : like interactive OLAP-style query, Sequential Access (big scan), Random Access (narrow scan).

Building CarbonData

CarbonData is built using Apache Maven, to build CarbonData

Online Documentation

Experimental Features

Some features are marked as experimental because the syntax/implementation might change in the future.

  1. Hybrid format table using Add Segment.
  2. Accelerating performance using MV on parquet/orc.
  3. Merge API for Spark DataFrame.
  4. Hive write for non-transactional table.

Integration

Other Technical Material

Fork and Contribute

This is an active open source project for everyone, and we are always open to people who want to use this system or contribute to it. This guide document introduce how to contribute to CarbonData.

Contact us

To get involved in CarbonData:

About

Apache CarbonData is an open source project of The Apache Software Foundation (ASF).