PostgreSQL
57 practice items · needed by 3 roles
Easy 10Medium 23Hard 24
Practice questions
- Benefit of INCLUDE in an indexmedium
- Workers block each other on a jobs tablehard
- Two doctors go off call at oncehard
- Table bloat that VACUUM will not fixhard
- Index for the few pending rowshard
- Adding an index to a live big tablehard
- Unique email with soft deleteshard
- Write skew under snapshot isolationhard
- Logical vs physical backupeasy
- Why a write-ahead log existseasy
- Read-only access for analystseasy
- What pg_hba.conf controlseasy
- View vs materialized vieweasy
- Seeing what is running noweasy
- Cancel or terminate a sessioneasy
- Gaps in auto-increment IDseasy
- Storing event timeseasy
- FATAL: too many clientseasy
- Reading an EXPLAIN ANALYZE planmedium
- Why PostgreSQL needs VACUUMmedium
- What PITR needsmedium
- Why use a connection poolermedium
- Covering indexmedium
- Which query to tune firstmedium
- UNIQUE column with NULLsmedium
- Adding an index on a live tablemedium
- Sort Method: external mergemedium
- Bad plan right after a bulk loadmedium
- Sizing shared_buffersmedium
- Session state behind pgBouncermedium
- Workers fighting over jobsmedium
- Reports cancelled on the replicamedium
- Is pg_dump consistent?medium
- Disk not freed after a big deletemedium
- Bloat from an idle sessionmedium
- A migration froze the whole appmedium
- Indexing only pending rowsmedium
- Searching inside textmedium
- Fast JSONB filtersmedium
- Counting a huge table quicklymedium
- Transaction ID wraparoundhard
- Index ignored because of a functionhard
- Disk filling with WALhard
- Prepared statement slows down laterhard
- Estimates wrong for city and zip codehard
- Logical replication stopped after a migrationhard
- pg_upgrade --link and rollbackhard
- pg_wal growing without limithard
- Unique email on a partitioned tablehard
- Deleting old data every monthhard
- Primary demoted when etcd is unreachablehard
- WAL volume spikes after checkpointshard
- Row-level security not appliedhard
- Risky SECURITY DEFINER functionhard
- Indexes bloat on a counter tablehard
- OOM killer after raising work_memhard
- Locks held by nobodyhard