1. DON'T YOU
(FORGET
ABOUT ME)
PHP Meetup Lisboa 2023
Things developers forget to
remember not to forget
Talk by Bernd Alter

2. PHP Meetup Lisboa 2023
Bernd Alter
Co-CTO at Turbine Kreuzberg GmbH
Twitter: @bazoo0815
Experience:
years developer
years PHP
years eCommerce
years Spryker
25+
20+
10+
7+

3. PHP Meetup Lisboa 2023
DEVELOPERS
ONLY CARE ABOUT
FUNCTIONALITY

4. PHP Meetup Lisboa 2023
"WORKS ON MY MACHINE"
DATABASE
Local development
❏ small dataset
❏ queries are fast
❏ no memory issues
❏ no latency
❏ indexes don't really matter
Production system
❏ large(r) dataset
❏ queries are slower
❏ memory/load issues
❏ large(r) latency between services/components
❏ missing indexes (can) slow down queries

5. PHP Meetup Lisboa 2023
"WORKS ON MY MACHINE"
TRAFFIC
Production system
❏ (huge) traffic
❏ concurrency
❏ blocking requests
❏ lack of resources
Local development
❏ no traffic (it's just you!)
❏ single requests/processes
❏ no concurrency
❏ all resources just for you

6. PHP Meetup Lisboa 2023
POSSIBLE SOLUTIONS
❏ SCALING
❏ PERFORMANCE OPTIMIZATION
❏ CACHING

7. PHP Meetup Lisboa 2023
SCALING
Easy solution:
Throw more resources at it!
Downside:
❏ more complex orchestration
❏ increasing infrastructure costs
(resources + devops ⇒ money)

8. PHP Meetup Lisboa 2023
What do you consider a large dataset
in your day-to-day business?
(quick show of hands)
100.000 entries?
1.000.000 entries?
10.000.000 entries?
100.000.000 entries?
more?
DATABASE PERFORMANCE

9. PHP Meetup Lisboa 2023
Consider payload size of query result set
❏ transfer time matters
❏ only fetch data you need
❏ limit columns in SELECT
Example: table with ~1.200 rows, total size 42 MB, avg row size ~40kB
250ms
3.5 s
DATABASE PERFORMANCE
vs
(=14x faster)
select * from myTable;
select id from myTable;
PAYLOAD SIZE

10. PHP Meetup Lisboa 2023
Set proper indexes
❏ analyze your queries, not your tables
(EXPLAIN is your friend!)
❏ use composite indexes
DATABASE PERFORMANCE
INDEX ANALYSIS/OPTIMIZATION
Remember: TANSTAAFL!
❏ 'no free lunch' principle: indexes come at a cost
❏ avoid large/many indexes on tables with many write operations
❏ avoid unnecessary indexes
CREATE INDEX myIndex ON myTable (lastname, firstname);
✔ SELECT * FROM myTable WHERE lastname = ‘Smith’ AND firstname = ‘John’;
✔ SELECT * FROM myTable WHERE lastname = ‘Smith’;
✖ SELECT * FROM myTable WHERE firstname = ‘John’ and lastname = ‘Smith’;
✖ SELECT * FROM myTable WHERE firstname = ‘John’;
Index used for queries:
← size order matters!

11. PHP Meetup Lisboa 2023
Common approach: LIMIT/OFFSET
❏ query performance is bad
Use keyset pagination (or seek pagination)
❏ no read-ahead needed
❏ only required rows are fetched/read
+ constant execution time
+ real pagination (no missed entries)
− only previous/next page (no page jumps)
DATABASE PERFORMANCE
KEYSET/CURSOR PAGINATION

12. PHP Meetup Lisboa 2023
Common approach: LIMIT/OFFSET
❏ query performance is bad
Use keyset pagination (or seek pagination)
❏ no read-ahead needed
❏ only required rows are fetched/read
+ constant execution time
+ real pagination (no missed entries)
− only previous/next page (no page jumps)
DATABASE PERFORMANCE
KEYSET/CURSOR PAGINATION

13. PHP Meetup Lisboa 2023
DATABASE PERFORMANCE
KEYSET/CURSOR PAGINATION

14. PHP Meetup Lisboa 2023
Don't hit the database at all (or at least less)
❏ use bulk operations over single operations
❏ select as much data at once as possible
❏ Common Table Expressions (CTE)
❏ UPSERTs for write operations
❏ avoid unnecessary queries
DATABASE PERFORMANCE
INSERT INTO myTable (...) VALUES (...) ON DUPLICATE KEY UPDATE SET ...; (MySQL)
ON CONFLICT (...) DO UPDATE SET ...; (Postgres)

15. PHP Meetup Lisboa 2023
CACHING
For how long? ❏ as long as possible
❏ usually trade-off between up-to-dateness and performance
How? ❏ prepare data (aggregate/transform)
❏ in-process caching (in PHP: static (member) variables)
❏ browser-caching
❏ key-value storage (e.g. Memcache, Redis)
❏ reverse proxy (e.g. Varnish)
What? ❏ time-/resource-consuming operations
❏ often used/requested data

16. PHP Meetup Lisboa 2023
5 days?
5 hours?
5 min?
5 sec?
CACHING
What would you consider a reasonable
amount of time to cache for?
(quick show of hands)

17. PHP Meetup Lisboa 2023
Even short caching periods (TTL) can boost your application’s performance significantly
CACHING
HOW LONG?
Example: Universal Music community chat (~2008)
❏ simple iframe with latest 50 messages
❏ ajax-reload every 10s
❏ ~1.000 concurrent users
⟶ ~6.000 req/min

18. PHP Meetup Lisboa 2023
Even short caching periods (TTL) can boost your application’s performance significantly
CACHING
HOW LONG?
Solution:
❏ local file cache with TTL of 5s
Example: Universal Music community chat (~2008)
❏ simple iframe with latest 50 messages
❏ ajax-reload every 10s
❏ ~1.000 concurrent users
⟶ ~6.000 req/min
—> 12 req/min (500x less)

19. PHP Meetup Lisboa 2023
CACHING
❏ ensure fast, responsive experience for all users
❏ use stale-while-revalidate mechanism
(supported by all modern browsers)
❏ after first caching, all users get always
(sufficiently) up-to-date data
ADVANCED TECHNIQUES

20. PHP Meetup Lisboa 2023
Try to make all your non-production environments as production-like as possible:
DEVELOP PRODUCTION-LIKE
❏ replicate infrastructure in development, testing and staging environments
❏ use Docker
❏ ideal: use same components/services in exactly same version and resources (CPU, memory, etc.)
❏ at least: use same components/services in same major version and similar resources
❏ use production-like dataset for development and staging/testing
❏ ideal: complete anonymized/pseudonymized production dump (-->GDPR!)
❏ at least: similar amount of data for crucial entities, e.g. products, prices, customers in ecommerce

21. PHP Meetup Lisboa 2023
There is no such thing as 'another production system'
DEVELOP PRODUCTION-LIKE
DISCLAIMER
You cannot duplicate your production system.
Period.
Live with it …
❏ traffic is different
❏ state of data is different
❏ services/components have different versions
❏ …

22. PHP Meetup Lisboa 2023
FEATURE TRAP
❏ also work on:
❏ tech debt
❏ updates
❏ refactoring
❏ maintenance tasks
❏ no immediate, but long-term business value
❏ stand up to your PO or stakeholders!
"WE HAVE TO BUILD FEATURES,
WE DON'T HAVE TIME FOR OTHER STUFF"

23. PHP Meetup Lisboa 2023
LINKS
❏ Use The Index, Luke
❏ No offset: We need tool support for keyset pagination
❏ SQL CTE (WITH Clause): The Ultimate Guide - Database Star
❏ Staleness and revalidation
❏ GitHub - DivanteLtd/anonymizer: Universal tool to anonymize database
❏ Blackfire.io - PHP profiling tool

24. PHP Meetup Lisboa 2023
QUESTIONS?

25. PHP Meetup Lisboa 2023
FOR LISTENING!