Postgres is enough for 99% of projects
You probably don't need MongoDB, ClickHouse or DynamoDB. Postgres handles JSON, full-text search, time series and queues fine.
Postgres has JSONB columns. You can store and query JSON documents like Mongo with proper indexes.
Full-text search via tsvector. Good enough for blogs, e-commerce, internal tools without Elasticsearch.
TimescaleDB extension turns Postgres into a time-series DB. pg_cron handles scheduled jobs. PgBouncer handles 10k connections.
Pick a specialised DB only when Postgres actually fails on your workload, not because Hacker News told you to.