[MDEV-14094] benchmark effects of innodb change buffer Created: 2017-10-19  Updated: 2021-07-06  Resolved: 2021-07-06

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - InnoDB
Fix Version/s: N/A

Type: Task Priority: Major
Reporter: Axel Schwenke Assignee: Axel Schwenke
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-515 innodb bulk insert Closed
relates to MDEV-11634 Improve the InnoDB change buffer Closed

 Description   

In order to make an educated decision to drop the change buffer, benchmark suitable workloads and check effect of change buffer turned on vs. off.



 Comments   
Comment by Axel Schwenke [ 2017-11-21 ]

I did a benchmark with 10.2.9 and sysbench OLTP write-only. The workload is 18 updates per transaction, changing the value of an indexed column. I have 3 result sets, restricting the size of the change buffer to 25% (default), 50% and 0% (aka turned off) of the buffer pool.

Numbers (transactions per second, bigger=better)

threads 25%     50%     0%
1       436.93  454.15  414.97
2       1128.5  1108.0  1072.1
4       2179.0  2152.6  2256.9
8       4353.1  4355.5  4169.6
16      7659.4  7623.6  7181.1
32      10250   10415   10317
64      11032   11139   10782
128     11447   11543   11104
256     11424   11452   11161

Conclusion: turning off the change buffer does affect performance, mostly for light to medium load.

Comment by Marko Mäkelä [ 2017-11-21 ]

axel, thank you for running the benchmarks.
I think that we should rerun the benchmark after implementing InnoDB bulk-loading (DML transactions on an empty InnoDB table or partition), some time during the 10.4 development.

Comment by Marko Mäkelä [ 2019-02-04 ]

MDEV-515 will not make it to 10.4, but will hopefully be in 10.5.

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