When do you use jsonb, and when don’t you? How do you make it fast? What operators are available, and what can they do? How will this change? These are all very good questions, but jsonb support in Postgres moves so fast that it’s hard to keep up. In this talk, you will get details on these topics, complete with practical examples and real-world stories: - When to use jsonb, what it’s good for, and when to not use it - Operators and how to use them effectively - Indexing, operator support for indexes, and the tradeoffs involved - Postgres 12 improvements and new features

1. Colton Shepard
PostgresOpen 2019

2. What is all this, anyways?
JavaScript Object Notation Data Interchange Format
RFC 7158
Human readable lightweight data format
One of 2 Postgres JSON data types.
Decomposed for storage, not stored as string
• Fast and indexable
• High disk usage

3. Good use cases
Entity–attribute–value model tables

4. Customer Story!

5. Less Good Use Cases: Statistics Gathering Issues

6. Other Less Good Use Cases

7. Customer Story: Heap Analytics
https://heap.io/blog/engineering/when-to-avoid-jsonb-in-a-postgresql-schema

8. Customer Story: Anonymous, Inc.

9. Operators

10. -> and ->>

11. The ? operator
Does this string exist as a top-level key within the JSON value?

12. The ? operator
What about this array of strings?

13. The ? operator

14. The @ operator

15. #> and #>>

16. Operator-friendly indexes

17. B-Tree

18. B-Tree Function Index

19. Hash

20. Hash function indexes

21. GiST, SP-GiST, and BRIN

22. GIN
This

23. GIN with jsonb_path_ops

24. GIN with jsonb_ops (default)

25. Special mention: GIN function index with gin_trgm_ops

26. Postgres 12
New datatype: jsonpath
Provides a binary representation of the parsed SQL/JSON path expression
1. .key returns object member with specified key
2. .* returns all object members at current level
3. .** returns all object members at current level and below
4. .**{level} or .**{start_level to end_level} returns all at specified level(s)
5. [subscript, ...] returns the value at specified array location
https://www.postgresql.org/docs/devel/datatype-json.html#DATATYPE-JSONPATH

27. Postgres 12: The jsonb_path_query operator

28. Postgres 12: jsonb_path_query with .* and .**

29. Postgres 12: jsonb_path_query with .**{level}

30. Postgres 12: jsonb_path_query with arrays

31. Postgres 12: the jsonb_path_exists operator
Gives bool indicating whether the path exists.

32. Postgres 12: the jsonb_path_match operator
This allows for any logic that’ll output Boolean results

33. Postgres 12: the jsonb_path_query_array operator
Much like jsonb_path_query, but you get an array instead:

34. Postgres 12: the jsonb_path_query_first operator
Get first matching result:

35. Conclusion

36. General resources to
learn more
https://www.youtube.com/watch?v=AeMaBwd90SI
https://heap.io/blog/engineering/when-to-avoid-jsonb-in-a-
postgresql-schema
https://bitnine.net/blog-postgresql/postgresql-internals-jsonb-
type-and-its-indexes/
https://www.citusdata.com/blog/2016/07/14/choosing-nosql-
hstore-json-jsonb/
https://www.postgresql.org/docs/12/functions-
json.html#FUNCTIONS-SQLJSON-PATH
https://paquier.xyz/postgresql-2/postgres-12-jsonpath/
https://www.citusdata.com/blog/2016/07/25/sharding-json-in-
postgres-and-performance/

37. @Azure Database for MySQL, PostgreSQL & MariaDB