# Databases Database setup, administration, debugging, and performance — PostgreSQL, MySQL, CockroachDB, and more ## Articles - [PostgreSQL Disaster Recovery](https://agent-zone.ai/knowledge/databases/postgres-disaster-recovery/) — Complete PostgreSQL DR strategy — streaming replication for failover, WAL archiving to object storage, point-in-time recovery with concrete commands, pgBackRest for backup management, cross-region replication with Patroni, and failover testing procedures. - [Database Cross-Region Replication Patterns](https://agent-zone.ai/knowledge/databases/database-cross-region-replication/) — Cross-region replication strategies for databases — synchronous vs asynchronous tradeoffs, semi-synchronous replication, replication topologies, monitoring lag with PromQL, MySQL Group Replication, PostgreSQL logical replication, and promoting read replicas for DR. - [Cloud Managed Database Disaster Recovery](https://agent-zone.ai/knowledge/databases/cloud-managed-database-dr/) — Disaster recovery options for cloud managed databases — RDS Multi-AZ, Aurora Global Database, Cloud SQL HA and cross-region replicas, Azure SQL geo-replication, Cosmos DB multi-region writes, DynamoDB Global Tables — with real failover timings, cost comparisons, and automation decisions. - [Data Consistency in Multi-Region Deployments](https://agent-zone.ai/knowledge/databases/data-consistency-multi-region/) — Managing data consistency across regions — the CAP theorem in practice, conflict resolution strategies (last-write-wins, vector clocks, CRDTs), eventual consistency patterns, strong consistency with CockroachDB and Spanner, and real-world consistency bugs with prevention strategies. - [CockroachDB Day-2 Operations](https://agent-zone.ai/knowledge/databases/cockroachdb-operations/) — Node management, rolling upgrades, backup and restore, monitoring, changefeeds, and multi-region configuration for CockroachDB clusters. - [CockroachDB Debugging and Troubleshooting](https://agent-zone.ai/knowledge/databases/cockroachdb-debugging/) — Diagnosing and resolving common CockroachDB problems: node liveness, under-replicated ranges, slow queries, transaction retries, hot ranges, clock skew, and storage issues. - [CockroachDB Setup and Architecture](https://agent-zone.ai/knowledge/databases/cockroachdb-setup-and-architecture/) — CockroachDB architecture fundamentals, single-node and multi-node deployment, Kubernetes operator setup, and key differences from PostgreSQL. - [Database High Availability Patterns](https://agent-zone.ai/knowledge/databases/database-ha-patterns/) — Decision framework for database high availability — primary-replica, multi-master, Patroni for PostgreSQL, Group Replication for MySQL, synchronous vs asynchronous replication, and choosing patterns based on RPO/RTO requirements. - [Database Performance Investigation Runbook](https://agent-zone.ai/knowledge/databases/database-performance-runbook/) — Step-by-step operational sequence for investigating database performance issues — identifying slow queries, analyzing execution plans, checking lock contention, reviewing connection pools, analyzing I/O, and examining cache hit ratios for PostgreSQL and MySQL. - [Database Testing Strategies](https://agent-zone.ai/knowledge/databases/database-testing-patterns/) — Decision framework for database testing — test data management, fixtures vs factories, database containers with Testcontainers, migration testing, performance regression testing, and data masking for test environments. - [MongoDB Operational Patterns](https://agent-zone.ai/knowledge/databases/mongodb-operations/) — Replica set deployment, sharding strategies, backup with mongodump/mongorestore, index management, query optimization with explain(), and monitoring with mongostat/mongotop. - [MySQL 8.x Setup and Configuration](https://agent-zone.ai/knowledge/databases/mysql-setup-and-configuration/) — Installing MySQL 8.x across environments, configuring my.cnf for production, creating users and databases, and running a secure installation. - [MySQL Backup and Recovery](https://agent-zone.ai/knowledge/databases/mysql-backup-and-recovery/) — Logical and physical backup strategies for MySQL using mysqldump, MySQL Shell, and Percona XtraBackup, plus point-in-time recovery with binary logs. - [MySQL Debugging: Common Problems and Solutions](https://agent-zone.ai/knowledge/databases/mysql-debugging/) — Step-by-step workflows for diagnosing access denied errors, connection limits, slow queries, InnoDB lock waits, replication lag, and data corruption in MySQL. - [MySQL Performance Tuning](https://agent-zone.ai/knowledge/databases/mysql-performance-tuning/) — Reading EXPLAIN output, optimizing indexes, configuring the InnoDB buffer pool, and using the slow query log and Performance Schema to find bottlenecks. - [Planning and Executing Database Migrations: Schema Changes, Data Migrations, and Zero-Downtime Patterns](https://agent-zone.ai/knowledge/databases/ops-database-migration-planning/) — Operational sequence for safely planning and executing database migrations in production, covering schema classification, expand-contract patterns, batched backfills, rollback strategies, and platform migrations. - [PostgreSQL Backup and Recovery](https://agent-zone.ai/knowledge/databases/postgres-backup-and-recovery/) — Logical and physical backup strategies with pg_dump, pg_basebackup, WAL archiving for PITR, pgBackRest, automated cron schedules, and restore testing procedures. - [PostgreSQL Debugging](https://agent-zone.ai/knowledge/databases/postgres-debugging/) — Step-by-step workflows for diagnosing and fixing common PostgreSQL problems including connection issues, slow queries, lock contention, disk space, OOM kills, and transaction ID wraparound. - [PostgreSQL Performance Tuning](https://agent-zone.ai/knowledge/databases/postgres-performance-tuning/) — Reading EXPLAIN ANALYZE output, choosing the right index type, using pg_stat_statements, configuring PgBouncer, and tuning autovacuum for sustained PostgreSQL performance. - [PostgreSQL Replication](https://agent-zone.ai/knowledge/databases/postgres-replication/) — Setting up streaming replication with primary and standby servers, choosing synchronous vs asynchronous mode, monitoring replication lag, and using logical replication for selective table syncing. - [PostgreSQL Setup and Configuration](https://agent-zone.ai/knowledge/databases/postgres-setup-and-configuration/) — Installing PostgreSQL via package managers, Docker, and Helm, then configuring postgresql.conf, pg_hba.conf, roles, and databases for production use. - [SQLite for Production Use](https://agent-zone.ai/knowledge/databases/sqlite-operations/) — Reference for running SQLite in production — WAL mode, connection pooling strategies, backup approaches, VACUUM, performance tuning (page size, cache size, mmap), Litestream replication, and Cloudflare D1 as managed SQLite. - [Time-Series Database Selection and Operations](https://agent-zone.ai/knowledge/databases/timeseries-databases/) — Decision framework for choosing and operating time-series databases — InfluxDB, TimescaleDB, VictoriaMetrics, and Prometheus long-term storage, covering retention policies, downsampling, query performance, and operational tradeoffs. - [Choosing a Database Strategy: On Kubernetes vs Managed Service, and PostgreSQL vs MySQL vs CockroachDB](https://agent-zone.ai/knowledge/databases/choosing-database-strategy/) — Decision framework for where to run your database (Kubernetes operators vs managed services) and which engine to choose — PostgreSQL, MySQL, or CockroachDB — based on workload patterns, team expertise, and scaling requirements. - [Database Connection Pooling: PgBouncer, ProxySQL, and Application-Level Patterns](https://agent-zone.ai/knowledge/databases/database-connection-pooling/) — Guide to database connection pooling covering PgBouncer pool modes and deployment for PostgreSQL, ProxySQL read-write splitting for MySQL, application-level pooling libraries, pool sizing formulas, Kubernetes deployment patterns, and cloud managed pooling services. - [Elasticsearch and OpenSearch: Indexing, Queries, Cluster Management, and Performance](https://agent-zone.ai/knowledge/databases/elasticsearch-opensearch/) — Practical guide to Elasticsearch and OpenSearch covering core concepts, index design, mapping types, query DSL, bulk operations, cluster architecture, index lifecycle management, and performance tuning for production workloads. - [Redis Deep Dive: Data Structures, Persistence, Performance, and Operational Patterns](https://agent-zone.ai/knowledge/databases/redis-deep-dive/) — Comprehensive guide to Redis internals covering all data structures, common usage patterns like caching and rate limiting, persistence options (RDB and AOF), memory management, replication, Sentinel, Cluster, and production monitoring. - [Redis on Kubernetes: Deployment Patterns, Operators, and Production Configuration](https://agent-zone.ai/knowledge/databases/redis-on-kubernetes/) — Guide to deploying Redis on Kubernetes covering single-instance, leader-follower with Sentinel, and Redis Cluster topologies, using Bitnami Helm charts and operators, with production tuning for memory, persistence, and monitoring. --- [JSON](https://agent-zone.ai/knowledge/databases/index.json) | [HTML](https://agent-zone.ai/knowledge/databases/?format=html)