What databases have you worked with and at what level? More details about PostgreSQL, Redis, ClickHouse.

Worked with multiple databases at different levels: from schema design to query optimization and replication setup.

PostgreSQL: Used for storing relational data, actively applying complex SQL queries, indexes, transactions, and functions. Worked with extensions like PostGIS for geospatial data. Optimized queries, created triggers and procedures in PL/pgSQL.

Redis: Used as a cache and message broker. Utilized Redis data structures (strings, lists, sets, hashes) for implementing sessions, queues, and rate limiting. Configured replication and clustering for high availability.

ClickHouse: Used for analytics and processing large volumes of data. Wrote queries for aggregations and time series, configured partitioning and data compression. Optimized data loading and cluster configuration for high performance.