This document discusses techniques for continuously delivering database changes, including database refactoring. It describes strategies like splitting tables and columns, adding transition periods, using versioning, automation with testing, and making changes incrementally and reversibly. Database refactoring includes structural, data quality, referential integrity, and transformation changes. Tools, strategies for low risk releases, and patterns like branch by abstraction and strangler are recommended to support evolutionary development and continuous delivery of database changes.

1. Expand Contract Pattern
for Continuous Delivery of Databases

2. https://pixabay.com/en/hands-hand-raised-hands-raised-220163/

3. Good Karma
Story-telling CRM because Facts Tell but Stories Sell http://goodkarmayoga.in/

4. Iterations https://pixabay.com/illustrations/recursion-icon-iteration-icon-2865934/

5. Evolvability https://www.dreamstime.com/

6. Sacrificial Architecture
https://www.martinfowler.com/bliki/SacrificialArchitecture.html

7. Move fast and break nothing
https://github.blog/2015-12-15-move-fast/

8. Upgrading Rails
https://github.blog/2018-09-28-upgrading-github-from-rails-3-2-to-5-2/

9. Techniques https://pixabay.com/photos/watercolor-tusche-indian-ink-wet-384873
/

10. Incremental https://pixabay.com/vectors/arrow-business-financial-graph-1295953/

11. Parallel Implementation https://www.martinfowler.com/bliki/ParallelChange.html

12. https://martinfowler.com/bliki/BranchByAbstraction.html
Branch by Abstraction

13. https://continuousdelivery.com/implementing/architecture/
Strangler Pattern

14. https://pixabay.com/vectors/abc-alphabet-blocks-toy-148517/Basics

15. https://martinfowler.com/books/refactoring.html
Refactoring is a controlled technique for improving the design of
an existing code base. Its essence is applying a series of small
behavior-preserving transformations, each of which "too small to
be worth doing".
However the cumulative effect of each of these transformations
is quite significant.
Refactoring

16. https://continuousdelivery.com/
Ability to get changes of all types—including new features,
configuration changes, bug fixes and experiments—into
production, or into the hands of users, safely and quickly in a
sustainable way.
Continuous Delivery

17. Database? https://pixabay.com/illustrations/question-help-question-mark-answer-1127660/

18. A database refactoring is a small change to your
database schema (the table structures, data itself,
stored procedures, and triggers) which improves its
design without changing its semantics.
http://databaserefactoring.com/

19. • Enables Continuous Delivery
• Supports evolutionary development
http://databaserefactoring.com/

20. https://www.dreamstime.com/stock-photos-example-stamp-image28420393

21. Split Column

22. customer_id
booking_date
status
trial_bookings

23. Transition
customer_id
status[old field]
booking_date
attendance_status
membership_status
trial_bookings

24. Initial sync https://git-scm.com/downloads/logos
UPDATE trial_bookings
SET attendance_status = 1, membership_status = 0
WHERE status = 1
UPDATE trial_bookings
SET attendance_status = 0, membership_status = 1
WHERE status = 2
UPDATE trial_bookings
SET attendance_status = 1, membership_status = 1
WHERE status = 3

25. Sync https://git-scm.com/downloads/logos

26. Transition https://git-scm.com/downloads/logos
customer_id status booking_date attendance_status membership_status
10001 1 2017-01-01 1 0
10002 2 2017-01-01 0 1
10003 3 2017-01-01 1 1

27. New Schema
customer_id
booking_date
attendance_status
membership_status
trial_bookings

28. New SchemaTransition PeriodOld Schema
customer_id
booking_date
attendance_status
membership_status
trial_bookings
customer_id
booking_date
attendance_status
membership_status
trial_bookings
customer_id
status[old field]
booking_date
attendance_status
membership_status
trial_bookings

29. Split Table

30. billing_cycles
customer_id
validity_starts_at
valid_until
payment_mode
Payment_made_at
amount_paid

31. payments
billing_cycle_id
payment_mode
payment_made_at
amount_paid
Transition
billing_cycles
customer_id
validity_starts_at
valid_until
billable_amount
payment_mode
payment_made_at
amount_paid
* 1

32. Initial sync https://git-scm.com/downloads/logos
INSERT INTO payments (
billing_cycle_id, payment_mode, payment_made_at, amount_paid
)
SELECT id, payment_mode, payment_made_at, amount_paid
FROM billing_cycles

33. Sync https://git-scm.com/downloads/logos

34. Transition https://git-scm.com/downloads/logos
customer_id validity_starts_at validity_until billable_amount payment_mode payment_made_at amount_paid
10001 2017-01-01 2017-03-01 10000 1 2017-01-01 10000
10002 2017-04-01 2017-05-01 5000 0 2017-04-01 5000
10003 2017-06-01 2017-12-31 15000 1 2017-06-01 10000
billing_cycle_id payment_mode payment_made_at amount_paid
15001 1 2017-01-01 10000
15002 0 2017-04-01 5000
15003 1 2017-06-01 10000
billing_cycles
payments

35. payments
billing_cycle_id
payment_mode
payment_made_at
amount_paid
New Schema
billing_cycles
customer_id
validity_starts_at
valid_until * 1

36. New Schema
Transition Period
Old Schema
payments
billing_cycle_id
payment_mode
payment_made_at
amount_paid
billing_cycles
customer_id
validity_starts_at
valid_until
payment_mode
Payment_made_at
amount_paid
billing_cycles
customer_id
validity_starts_at
valid_until
payment_mode
payment_made_at
amount_paid
billable_amount payments
billing_cycle_id
payment_mode
payment_made_at
amount_paid
billing_cycles
customer_id
validity_starts_at
valid_until

37. https://martinfowler.com/articles/evodb.html

38. Types of Refactoring
★ Structural Refactoring
★ Data Quality Refactoring
★ Referential Integrity Refactoring
★ Transformation
★ Architectural Refactoring
★ Method Refactoring

39. https://pixabay.com/vectors/abc-alphabet-blocks-toy-148517/Basics

40. Versioning https://git-scm.com/downloads/logos

41. Strategies https://git-scm.com/downloads/logos
★ Build Number
★ Timestamp
★ Unique Identifier

42. https://pixabay.com/photos/gears-cogs-machine-machinery-1236578/
Automation

43. Tests https://pixabay.com/vectors/button-yes-no-red-green-icon-32259/

44. Deploy https://pixabay.com/vectors/rocket-icon-symbol-gui-internet-1976107/

45. https://pixabay.com/en/strategy-arrows-building-startup-3224515/

46. Migration https://pixabay.com/photos/canada-geese-flying-formation-575262/

47. Transition period https://pixabay.com/photos/bridge-iron-old-pedestrian-metal-3181356/

48. Tools

50. Murphy’s Law https://www.flickr.com/photos/smemon/5471883005

51. Low risk releases https://pixabay.com/en/button-red-round-shiny-155149/

52. Small reversible steps https://www.slideshare.net/jallspaw/ops-metametrics-the-currency-you-pay-for-change

54. Atomicity and Ratcheting
Split Table - Database Refactoring
Continuous Delivery of Databases
Expand Contract Pattern - Continuous Delivery of Databases
Database Refactoring
Four Principles of Low-Risk Software Releases
Branch by Abstraction
Move Fast @ Github
Legacy Application Strangulation
Make Large Scale Changes Incrementally with Branch By Abstraction

55. Leena S N
@leenasn / leenasn@gmail.com
https://medium.com/@leenasn