PostgreSQL — the psql + SQL commands that come up daily

## psql session
`psql postgresql://user:pass@host:port/db` — connect via URL
`psql -h host -U user -d db` — connect with flags
`\q` — quit
`\?` — psql help
`\h` — SQL help (`\h SELECT`)

## Inspect
`\l` / `\list` — list databases
`\c dbname` — switch database
`\dt` / `\dt schema.*` — list tables
`\d table` — describe table
`\dn` — list schemas
`\du` — list users / roles

## Indexes + EXPLAIN
`\di` — list indexes
`EXPLAIN ANALYZE SELECT ...` — show actual execution plan + timing
`EXPLAIN (FORMAT JSON, ANALYZE, BUFFERS) ...` — full detail

## Performance peeks
`SELECT * FROM pg_stat_activity;` — current connections + queries
`SELECT * FROM pg_stat_statements ORDER BY total_exec_time DESC LIMIT 20;` — slowest queries (needs extension)
`SELECT pg_size_pretty(pg_database_size('db'));` — db size
`SELECT pg_size_pretty(pg_total_relation_size('table'));` — table size incl. indexes

## Backup + restore
`pg_dump -Fc dbname > db.dump` — custom-format dump
`pg_restore -d newdb db.dump` — restore
`pg_dump -Fc dbname | gzip > db.dump.gz` — compressed