MySQL Data Redistribution

Motivation

While B-Tree is a ubiquitous index structure used in managing data, it is well known for its low space utilization in nodes. Such space under-utilization is detrimental to flash storage in terms of cost and performance. In particular, the logical space waste in B-tree will amplify physical writes inside flash storage, worsening the transaction throughput.

Contribution

Our evaluation results from running OLTP benchmarks(TPC-C) using the data redistribution MySQL clearly show that those optimizations improve transaction throughput (i.e., more than 50%) with less space and cost (i.e., less than 40%) in flash storage. Also the overall index space utilization is improved.

Experiment Result

• TPCC-Result

• Index Space Utilization

Prerequisites & Installation Guide

1. Install prerequisites of mysql-5.6.26. Follow the instructions in the site.
2. Clone this repository.

$ git clone https://github.com/FlashSQL/MySQL-Data-Redistribution.git

3. Run mysqld server to run MySQL.
4. Compare with Vanilla MySQL and see how table size changes

Modified files compared to Vanilla MySQL

• storage/innobase/btr/btr0btr.cc
• storage/innobase/fil/fil0fil.cc
• storage/innobase/srv/srv0srv.cc
• storage/innobase/include/btr0btr.h
• storage/innobase/include/srv0srv.h
• storage/innobase/include/fil0fil.h

Implementation Details about Data Redistritbution

• added a new function in btr0btr.cc: btr_page_redistribute_before_split()
• returns the inserted record
• btr_page_redistribute_before_split() is called during btr_page_split_and_insert()(btr0btr.cc) before split is performed
• modifications in srv0srv and fil0fil are for adding table id and table name

References

• https://dev.mysql.com/