JSON vs JSONB — Complete Guide
JSON vs JSONB — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of PostgreSQL Tutorial on Toolliyo Academy.
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PostgreSQL Tutorial · Lesson 51 of 100
JSON vs JSONB
SQL ✓ → Advanced
Advanced · 2 — Production · ~6 min · PostgreSQL — JSONB & Modern Features
What is this?
json stores exact text with whitespace; jsonb stores parsed binary format — faster operators, indexable, no duplicate keys guarantee. Prefer jsonb for querying.
Why should you care?
PostgresVerse product attributes need filtering — jsonb @> and GIN indexes; json type is mainly for passthrough storage.
See it live — copy this example
Run in pgAdmin or psql.
SELECT
'{"color":"red","color":"blue"}'::json AS json_dup,
'{"color":"red","color":"blue"}'::jsonb AS jsonb_canonical;
SELECT (jsonb_canonical->>'color') AS winner;What happened?
- json keeps invalid duplicate keys as text.
- jsonb normalizes to one color key.
- Arrow operators work efficiently on jsonb.
Practice next
- Cast same string to json and jsonb; compare output.
- Store column as jsonb on new table attribute_test.
- Try = equality on jsonb documents.
- jsonb_pretty() for readable pgAdmin output.
- Convert json column: ALTER COLUMN specs TYPE jsonb USING specs::jsonb.
Remember
jsonb for query and index; json for exact text round-trip. jsonb removes insignificant whitespace. Both validate JSON syntax on insert.
PostgresVerse catalog migration
Team migrates specs from json to jsonb and adds GIN for facet search.
Outcome: Attribute filter API ships; storage slightly larger but queries 10x faster.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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