VACUUM FULL

What this does

Rewrites the entire table to reclaim space, holding ACCESS EXCLUSIVE for the full duration. Unlike plain VACUUM (SHARE UPDATE EXCLUSIVE, non-blocking), FULL blocks all reads and writes.

Safe rewrite

Use pg_repack for an online table rewrite that does not hold ACCESS EXCLUSIVE

-- pg_repack --table orders --no-superuser-check

Read more

• /blog/postgres-lock-mode-cheat-sheet
• /blog/ddl-lock-cheat-sheet

More in Destructive Operations

• DROP TABLE CRITICAL
• ALTER TABLE ... DROP COLUMN HIGH
• ALTER TABLE ... DROP CONSTRAINT MEDIUM
• DROP SCHEMA CRITICAL
• DROP SCHEMA ... CASCADE CRITICAL
• TRUNCATE CRITICAL