Presented at MariaDB Roadshow Hannover in March 2018

1. Maximizing
Performance via Tuning
and Optimization
Getting the most from MariaDB
Server
Jens Bollmann Consultant/Instructor
Ulrich Moser Consultant/Instructor

2. Agenda • General Best Practices
• Server, Storage, Network and O/S
• Connections & Pooling
• MariaDB Config Settings
• Query Tuning
• Q&A

3. MariaDB Server + InnoDB

4. General Best Practices
Maybe obvious, but worth repeating

5. • Service Level Agreements (SLAs)
– Individual Biz/App Transactions
– Throughput
– Latency (at percentile)
– Peaks of peaks or favorable scheduling?
• Translate to Database Transactions
Define Target

6. Capture Metrics
• Biz/App Transactions
– Code Instrumentation
– Synthetic Transactions
– Compare to defined SLAs
• Database Transactions
• Sub-system level
– Servers (Web, App, DB, etc…)
– Storage
– Network
– Database

7. History
Alerts
Leverage your Metrics

8. Avoiding Cliffs • Understand expected business volumes
• Watch system-level stats for saturation
• Stress testing
– Sysbench
– HammerDB
– TPC
– Many others….
– Custom

9. Server, Storage, Network and O/S
Core Infrastructure

10. • Dedicated Server
• Memory
– More usually helps (up to ~dataset size)
– Important with read-heavy + slow disk
• More CPUs
– Highly concurrent use cases
– Usually favored over faster CPUs
• Faster CPUs
– Less concurrent use cases
– Dataset fits in memory
Database Server

11. • Local or SAN over NAS
– Performance
• SSD over HHD
– Performance and MTBF
– SSD wear not usually a factor
• SSDs
– Consumer
– Prosumer
– PCIe
– NVMe
Storage

12. • Can be Bandwidth Hungry
– Regular client traffic
– Replication Traffic
– Rebuilding replicas from snapshots
• Stability matters for Replication
• Sometimes overlooked as potential bottleneck
• Efficient DNS setup*
Network

13. • vm.swappiness = 10
• ext4 or xfs for data files
• noatime for filesystem mounts
• ulimit changes
OS (Linux)
mariadb.com/kb/en/library/operating-system-optimizations/

14. Connections & Pooling
Applying Back Pressure

15. Back Pressure in the Full Stack
Firewall/LB Web Servers App Servers MaxScale MariaDB Server(s)

16. MariaDB Connection Controls
App Servers MaxScale
MariaDB Server(s)
max_connections
wait_timeout
thread_handling
thread_pool_max_threads
thread_pool_min_threads
thread_pool_idle_timeout
...
MariaDBDataSource
MariaDBPoolDataSource
maxPoolSize
minPoolSize
...
Outbound
persistpoolmax
persistmaxtime
Inbound
max_connections
connection_timeout

17. Further Reading
• Java Connector Pooling
mariadb.com/kb/en/library/pool-datasource-implementation/
• MaxScale
mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22/maxscale-configuration-
usage-scenarios/#server
mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22/maxscale-configuration-
usage-scenarios/#server
• Server Thread Pools
mariadb.com/kb/en/library/thread-pool-in-mariadb/
mariadb.com/kb/en/library/thread-pool-system-and-status-variables/

18. Configuration Settings
Common Settings with Performance Impact

19. • Runtime changes via SET GLOBAL
• Make permanent with changes to my.cnf
– Make sure you have right my.cnf
– Verify with SHOW GLOBAL
• One change at a time
• Production changes
– tested, reviewed, version controlled
Changing Config
Settings
my.cnf

20. Config Settings (1 of 2)
innodb_buffer_pool_size
innodb_log_file_size
innodb_file_per_table
query_cache_size
max_connections

21. Config Settings (2 of 2)
tmp_table_size
max_heap_table_size
join_buffer_size
sort_buffer_size

22. Query Tuning
There are always more queries to tune

23. Finding Slow
Queries
slow_query_log = 1
slow_query_log-file = /var/lib/mysql/myslow.log
long_query_time = 10
Pay attention to similar queries and the
query count

24. Analyzing Slow
Queries
EXPLAIN
SELECT *
FROM employees
WHERE MONTH(birth_date) = 8 G
id: 1
select_type: SIMPLE
table: employees
type: ALL
possible_keys: NULL
key: NULL
key_len: NULL
ref: NULL
rows: 299587
Extra: Using where

25. • Poor Indexing #1 Reason for poor
performance
• Basics of B-Tree Indexing same across
relational systems
• Space/Performance Tradeoff
• Write/Read Tradeoff
Indexing

26. • PRIMARY KEY = Clustered Index
• Secondary Indexes reference hold primary key
– keep PRIMARY KEY small
• InnoDB Table Stats
• Optimizer Hints
– https://mariadb.com/kb/en/library/optimizer-hints/
InnoDB
Indexing Tips

27. Query Tuning
SHOW STATUS
Global or Session
● Returns List of Internal Counters
● GLOBAL for System-Wide Status — Since Start-Up
● SESSION for Local to Client Connection
● FLUSH STATUS Resets Local Counters
● Monitor Changes to Counters to Identify Hot Spots
● Collect Periodically Status Snapshots to Profile
Traffic

28. Query Tuning
PERFORMANCE_SCHEMA
● Similar to INFORMATION_SCHEMA , but
Performance Tuning
● Monitors MariaDB Server Events
● Function Calls, Operating System Waits, Internal
Mutexes, I/O Calls
● Detailed Query Execution Stages (Parsing,
Statistics, Sorting)
● Some Features Storage Engine Specific
● Monitoring Lightweight and Requires No
Dedicated Thread
● Designed to be Used Iteratively with Successive
Refinement

29. Q&A

30. Thank you
jens@mariadb.com
ulrich.moser@mariadb.com

31. Appendix
Backup Slides and More