Database Knowledge Hub

DB Encyclopedia

Every database. Every pattern. Every command. The complete reference for DevOps & Platform Engineers.

40+
Databases
8
Categories
100+
Commands
4
Learning Paths
🔍 Explore Databases ⚡ Which DB for me?
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01 — Categories

The Database Universe

Eight major families of databases. Click any category to filter the encyclopedia below.

🌐
All Databases
40+ entries
🗄️
Relational (SQL)
8 databases
📄
Document
5 databases
🔑
Key-Value
5 databases
📊
Columnar / Wide
4 databases
🕸️
Graph
4 databases
📈
Time Series
4 databases
⚡
NewSQL / Distributed
5 databases
🔍
Search Engines
3 databases
02 — Encyclopedia

Database Profiles

Click any card to expand full details, use cases, and K8s deployment info.

🔍
03 — Compare

Feature Comparison Matrix

Compare key databases across critical attributes. Click headers to sort.

Database ↕ Type ↕ ACID H-Scale K8s Op. Cloud Open Src Best For ↕
04 — Wizard

Which Database Should I Use?

Answer 5 questions and get a tailored database recommendation.

05 — Cloud

Cloud Database Services

AWS vs Azure vs GCP — side-by-side managed database service mapping.

🟠 Amazon Web Services
Relational
Amazon RDSMySQL, Postgres, MariaDB, Oracle, SQL Server
Amazon AuroraMySQL/Postgres compatible, 5x performance
NoSQL Document
Amazon DocumentDBMongoDB compatible, fully managed
Key-Value
Amazon DynamoDBServerless, single-digit ms latency
ElastiCacheRedis & Memcached managed
Analytics
Amazon RedshiftData warehouse, columnar storage
Amazon KeyspacesCassandra compatible, serverless
Time Series
Amazon TimestreamPurpose-built time series
Graph
Amazon NeptuneProperty graph + SPARQL
Search
Amazon OpenSearchFork of Elasticsearch
🔵 Microsoft Azure
Relational
Azure SQL DatabaseFully managed SQL Server
Azure Database for PostgreSQLFlexible Server, Hyperscale
Azure Database for MySQLFlexible Server managed
NoSQL / Multi-model
Azure Cosmos DBMulti-model: SQL, Mongo, Cassandra, Gremlin
Key-Value
Azure Cache for RedisEnterprise Redis, managed
Azure Table StorageNoSQL structured storage
Analytics
Azure Synapse AnalyticsUnified analytics platform
Azure Data ExplorerFast log & telemetry analytics
Search
Azure AI SearchCognitive + vector search
Graph
Cosmos DB (Gremlin)Apache TinkerPop compatible
🟡 Google Cloud Platform
Relational
Cloud SQLMySQL, PostgreSQL, SQL Server managed
AlloyDBPostgres compatible, AI-optimized
NoSQL Document
Cloud FirestoreServerless document DB, real-time
Key-Value / Wide Column
Cloud BigtableHBase compatible, petabyte scale
MemorystoreRedis & Memcached managed
Analytics / Data Warehouse
BigQueryServerless data warehouse, ML built-in
Distributed SQL
Cloud SpannerGlobally distributed, strong consistency
Search
Vertex AI SearchEnterprise + vector search
Graph
Spanner GraphGraph queries on Spanner
06 — Kubernetes

Databases on Kubernetes

Production-grade database operators, patterns, and StatefulSet strategies for K8s.

🐘
PostgreSQL
CloudNativePG

CNCF-listed operator. Manages primary/replica topology, automated failover, WAL archiving to S3/GCS/Azure, connection pooling via PgBouncer sidecar.

StatefulSetCNCFHAPITR
🐬
MySQL
Percona Operator

Percona XtraDB Cluster operator. Group replication, ProxySQL load balancing, automated backup to S3, Monitoring via PMM.

StatefulSetXtraDBProxySQL
🍃
MongoDB
MongoDB Community Op.

Manages ReplicaSets and Sharded clusters. TLS, SCRAM auth, persistent volumes, automated recovery. Enterprise operator adds LDAP, Ops Manager.

ReplicaSetShardingTLS
📦
Redis
Redis Operator / Spotahome

Manages Redis Sentinel, Cluster modes. Spotahome operator supports Redis 7+, ACLs, TLS, PVC management. Redis Labs operator for enterprise.

SentinelClusterACL
🪨
Cassandra
K8ssandra Operator

Apache Cassandra on K8s. Multi-DC topology, Medusa backups, Stargate API layer (REST/GraphQL), automated repairs via Reaper.

Multi-DCMedusaReaper
⚡
ClickHouse
Altinity Operator

ClickHouse clusters with sharding and replication. ZooKeeper/ClickHouse Keeper managed automatically. Rolling updates, schema migrations.

ShardingColumnarZooKeeper
🔴
Elasticsearch
ECK (Elastic Cloud on K8s)

Official Elastic operator. Manages Elasticsearch, Kibana, APM Server, Fleet Server. TLS auto-provisioning, hot-warm-cold architecture.

ECKILMKibana
🔵
CockroachDB
CockroachDB Operator

Distributed SQL across K8s nodes. Geo-partitioning, automated rebalancing, Prometheus metrics, certificate rotation, rolling upgrades.

DistSQLGeoCRDB
💾
Velero — DB Backups
Backup Strategy

Use Velero with DB-specific hooks (pre/post backup scripts) for consistent snapshots. Combine with PVC snapshots for point-in-time recovery.

VeleroPVCHooks
07 — Cheatsheets

Command Reference

Copy-ready commands for every major database. No fluff.

Connection
# Connect to PostgreSQL psql -h hostname -U username -d dbname psql postgresql://user:pass@host/db # With SSL psql "sslmode=require host=db user=app"
Database Operations
\l -- list databases \c dbname -- connect to db \dt -- list tables \d tablename -- describe table \du -- list users \timing -- toggle timing
User & Permissions
CREATE USER app WITH PASSWORD 'pass'; CREATE DATABASE mydb OWNER app; GRANT ALL ON DATABASE mydb TO app; GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly; ALTER USER app CREATEDB;
Backup & Restore
# Backup pg_dump -Fc mydb > mydb.dump pg_dumpall > all.sql # Restore pg_restore -d mydb mydb.dump psql mydb < mydb.sql
Performance
-- slow queries SELECT query, mean_exec_time, calls FROM pg_stat_statements ORDER BY mean_exec_time DESC LIMIT 10; -- table bloat SELECT relname, n_dead_tup FROM pg_stat_user_tables ORDER BY n_dead_tup DESC;
Replication Status
-- on primary SELECT * FROM pg_stat_replication; -- replication lag SELECT now() - pg_last_xact_replay_timestamp() AS replication_delay; -- is standby? SELECT pg_is_in_recovery();
Connection
mysql -h host -u root -p mysql -u root -p mydb # Connection string mysql mysql://user:pass@host:3306/db
Database Operations
SHOW DATABASES; USE mydb; SHOW TABLES; DESCRIBE tablename; SHOW FULL PROCESSLIST; SHOW STATUS LIKE 'Threads%';
Backup & Restore
# Backup mysqldump -u root -p mydb > mydb.sql mysqldump --all-databases > all.sql # Restore mysql -u root -p mydb < mydb.sql
Replication
SHOW MASTER STATUS\\G SHOW SLAVE STATUS\\G SHOW REPLICA STATUS\\G -- MySQL 8+ START REPLICA; STOP REPLICA;
Connection & Shell
mongosh "mongodb://host:27017/db" mongosh --tls --tlsCertificateKeyFile cert.pem show dbs use mydb show collections
CRUD Operations
db.col.insertOne({name:"Eknatha"}) db.col.find({name:"Eknatha"}).pretty() db.col.updateOne({_id:x},{$set:{age:30}}) db.col.deleteMany({status:"inactive"}) db.col.countDocuments()
ReplicaSet Status
rs.status() rs.isMaster() // deprecated db.isMaster() rs.printReplicationInfo() rs.add("host:27017")
Backup
mongodump --uri "mongodb://host/db" \ --out /backup/ mongorestore --uri "mongodb://host" \ --dir /backup/db
Connection & Keys
redis-cli -h host -p 6379 -a password redis-cli --tls -h host KEYS pattern* # avoid in prod! SCAN 0 MATCH user:* COUNT 100 TTL key TYPE key
Data Structures
SET key value EX 3600 GET key HSET user:1 name Eknatha LPUSH queue item1 SADD tags devops k8s ZADD leaderboard 100 user1
Admin & Monitor
INFO server INFO memory INFO replication INFO keyspace MONITOR # live commands SLOWLOG GET 10 CLIENT LIST
Cluster & Sentinel
CLUSTER INFO CLUSTER NODES SENTINEL masters SENTINEL slaves mymaster SENTINEL failover mymaster
CQL Shell
cqlsh host -u cassandra -p password DESCRIBE KEYSPACES; USE mykeyspace; DESCRIBE TABLES; DESCRIBE TABLE mytable;
Cluster Status
nodetool status nodetool ring nodetool info nodetool tpstats nodetool compactionstats nodetool repair keyspace
08 — Learning

Learning Paths

Structured paths from zero to production-ready for DevOps & Platform Engineers.

01
🌱 Beginner
DB Fundamentals for DevOps

Understand database concepts, SQL basics, and how databases fit into modern application stacks.

  • 1ACID properties & CAP theorem
  • 2SQL vs NoSQL — when to use each
  • 3Indexes, joins, and query basics
  • 4Connection pooling concepts
  • 5Backup & restore fundamentals
02
🔧 Intermediate
PostgreSQL for Production

Deep dive into PostgreSQL — the de facto standard for most product companies. Ops-focused.

  • 1postgresql.conf tuning (memory, WAL)
  • 2Replication — streaming & logical
  • 3Patroni HA setup
  • 4pg_stat_statements & slow query tuning
  • 5Backup with pgBackRest / Barman
  • 6pgvector for AI/ML workloads
03
☸️ Advanced
Databases on Kubernetes

Run stateful databases reliably on Kubernetes using operators, StatefulSets, and GitOps.

  • 1StatefulSets vs Deployments
  • 2PV / PVC / StorageClass design
  • 3CloudNativePG operator setup
  • 4Velero backup with DB hooks
  • 5Monitoring with Prometheus exporters
  • 6GitOps for DB config management
04
☁️ Cloud Expert
Cloud Database Operations

Master managed database services on AWS, Azure, and GCP for Platform Engineering.

  • 1RDS vs Aurora — when to use each
  • 2Multi-AZ vs Read Replicas
  • 3Connection pooling with RDS Proxy
  • 4Terraform for RDS/CloudSQL provisioning
  • 5Cost optimization — instance right-sizing
  • 6DynamoDB — capacity planning & GSIs
09 — AI Advisor

Ask the DB Advisor

Describe your use case — get an instant recommendation powered by a built-in offline knowledge base. No internet required.

✦ Offline Knowledge Base — covers 10 use case categories, 25+ databases, K8s operators, cloud services
Your AI-powered database recommendation will appear here. Try one of the examples above or type your own use case.
10 — Tools

DB Tools Directory

12 fully functional database tools — all offline, all embedded. Click any tool to open it.

11 — Tutorials

Full Database Tutorials

Complete step-by-step guides — install, configure, operate, and deploy every major database on Kubernetes.

📖
Select a Tutorial
Choose any database from the sidebar to start learning. Each tutorial covers installation, core concepts, commands, K8s deployment, monitoring, and troubleshooting.
🐘 PostgreSQL 🐬 MySQL 🍃 MongoDB 📦 Redis 🪨 Cassandra ⚡ ClickHouse 🔍 Elasticsearch 🕸️ Neo4j ⏱️ TimescaleDB 🪲 CockroachDB
12 — Query Explainer

SQL Query Explainer

Paste any SQL query and get a plain-English breakdown of every clause, what it does, indexes it needs, and potential issues.

Paste your SQL query
Try:
🔍
Query breakdown will appear here
Paste a SQL query on the left and click Explain
13 — Glossary

Database Glossary

100+ database terms explained in plain English for DevOps & Platform Engineers.

14 — Quiz

DB Knowledge Quiz

Test your database knowledge across all categories. 60 questions, scored, with detailed explanations.

🧠
Ready to test your DB knowledge?
60 questions across PostgreSQL, MySQL, MongoDB, Redis, Cassandra, ClickHouse, Elasticsearch, K8s operators, and more. Each question has a detailed explanation.
Choose category:
15 — Daily Challenge

Daily DB Challenge

One new database challenge every day. Track your streak and progress.

0
Day Streak 🔥
Recent Challenges
Challenge Topics
16 — Data Type Picker

Data Type Picker

Describe what you need to store and get the right column type across PostgreSQL, MySQL, MongoDB, Cassandra, and DynamoDB — with storage size, constraints, and caveats.

What do you need to store?
— or describe it —
Quick picks:
🗂️
Select a data type
Pick a category or type your use case on the left