When should I use QuestDB instead of ScyllaDB?

Extremely fast time-series SQL queries with PostgreSQL wire protocol compatibility. Real-time financial market data, IoT sensor ingestion, and telemetry storage needing low latency. Teams wanting InfluxDB-like time-series performance with familiar SQL instead of a custom query language

When should I use ScyllaDB instead of QuestDB?

High-performance Cassandra-compatible wide-column store with lower latency via C++ implementation. Teams wanting Cassandra semantics with better throughput and without JVM GC pause latency spikes. Workloads where Cassandra's JVM garbage collection causes unpredictable tail latency

What are the main weaknesses of QuestDB?

Young project; ecosystem maturity and connector support are still growing. No built-in clustering in the open-source version — the cloud offering handles horizontal scaling. Write patterns that bypass the optimized append path can degrade performance significantly

What are the main weaknesses of ScyllaDB?

Cassandra compatibility is not 100%; subtle behavioral differences can surface during migration. Smaller community and ecosystem than Apache Cassandra for tooling and integrations. Self-managed deployment requires Cassandra operational expertise plus ScyllaDB-specific knowledge

QuestDB vs ScyllaDB: Key Differences for Python Data Engineering

Databases & Data Warehouses

QuestDB

Fast SQL Time Series Database

★ 4.5

Apache-2.0

pip install questdb

ScyllaDB

High-Performance Cassandra Alternative

★ 4.5

AGPL-3.0 (Community)

pip install scylla-driver

Side-by-Side Comparison

QuestDB

ScyllaDB

QuestDB

ScyllaDB

Best For

✓Extremely fast time-series SQL queries with PostgreSQL wire protocol compatibility
✓Real-time financial market data, IoT sensor ingestion, and telemetry storage needing low latency
✓Teams wanting InfluxDB-like time-series performance with familiar SQL instead of a custom query language

✓High-performance Cassandra-compatible wide-column store with lower latency via C++ implementation
✓Teams wanting Cassandra semantics with better throughput and without JVM GC pause latency spikes
✓Workloads where Cassandra's JVM garbage collection causes unpredictable tail latency

Best For

✓Extremely fast time-series SQL queries with PostgreSQL wire protocol compatibility
✓Real-time financial market data, IoT sensor ingestion, and telemetry storage needing low latency
✓Teams wanting InfluxDB-like time-series performance with familiar SQL instead of a custom query language

✓High-performance Cassandra-compatible wide-column store with lower latency via C++ implementation
✓Teams wanting Cassandra semantics with better throughput and without JVM GC pause latency spikes
✓Workloads where Cassandra's JVM garbage collection causes unpredictable tail latency

Weaknesses

•Young project; ecosystem maturity and connector support are still growing
•No built-in clustering in the open-source version — the cloud offering handles horizontal scaling
•Write patterns that bypass the optimized append path can degrade performance significantly

•Cassandra compatibility is not 100%; subtle behavioral differences can surface during migration
•Smaller community and ecosystem than Apache Cassandra for tooling and integrations
•Self-managed deployment requires Cassandra operational expertise plus ScyllaDB-specific knowledge

Weaknesses

•Young project; ecosystem maturity and connector support are still growing
•No built-in clustering in the open-source version — the cloud offering handles horizontal scaling
•Write patterns that bypass the optimized append path can degrade performance significantly

•Cassandra compatibility is not 100%; subtle behavioral differences can surface during migration
•Smaller community and ecosystem than Apache Cassandra for tooling and integrations
•Self-managed deployment requires Cassandra operational expertise plus ScyllaDB-specific knowledge

License

Apache-2.0

AGPL-3.0 (Community)

License

Apache-2.0

AGPL-3.0 (Community)

Install

pip install questdb

pip install scylla-driver

Install

pip install questdb

pip install scylla-driver

Rating

★ 4.5

Rating

★ 4.5

Key Features

QuestDB

1High-performance time-series SQL database with columnar storage
21.6 million rows per second single-node ingestion via InfluxDB line protocol
3SQL extensions: SAMPLE BY, LATEST ON, and ASOF JOIN for time-series
4PostgreSQL wire protocol compatibility for standard Python drivers
5Built-in web console with SQL editor and charting

ScyllaDB

1Cassandra-compatible NoSQL database written in C++ for 10x lower latency
2Shard-per-core architecture eliminates cross-core synchronization overhead
3Drop-in Cassandra replacement — uses the same CQL and drivers
4Compaction strategies optimized for write-heavy workloads
5ScyllaDB Cloud for fully managed deployment on AWS, GCP, and Azure

How Python Data Engineers Use These Tools

QuestDB

Python data engineers use `psycopg2` (PostgreSQL-compatible) or the QuestDB Python client to ingest high-frequency sensor or financial time-series data. QuestDB's SAMPLE BY clause enables time-bucketed aggregations in a single SQL statement — engineers run these from Python to compute minute or hourly summaries of millisecond-granularity event streams.

ScyllaDB

Python data engineers use ScyllaDB as a Cassandra replacement when latency is critical — the `cassandra-driver` library works unchanged since ScyllaDB is wire-compatible. Engineers migrating from Cassandra to ScyllaDB typically see P99 write latency drop from milliseconds to microseconds without any Python code changes.

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Individual Tool Pages

View QuestDB details →View ScyllaDB details →

Side-by-Side Comparison

QuestDB

ScyllaDB

QuestDB

ScyllaDB

Best For

✓Extremely fast time-series SQL queries with PostgreSQL wire protocol compatibility
✓Real-time financial market data, IoT sensor ingestion, and telemetry storage needing low latency
✓Teams wanting InfluxDB-like time-series performance with familiar SQL instead of a custom query language

✓High-performance Cassandra-compatible wide-column store with lower latency via C++ implementation
✓Teams wanting Cassandra semantics with better throughput and without JVM GC pause latency spikes
✓Workloads where Cassandra's JVM garbage collection causes unpredictable tail latency

Best For

✓Extremely fast time-series SQL queries with PostgreSQL wire protocol compatibility
✓Real-time financial market data, IoT sensor ingestion, and telemetry storage needing low latency
✓Teams wanting InfluxDB-like time-series performance with familiar SQL instead of a custom query language

✓High-performance Cassandra-compatible wide-column store with lower latency via C++ implementation
✓Teams wanting Cassandra semantics with better throughput and without JVM GC pause latency spikes
✓Workloads where Cassandra's JVM garbage collection causes unpredictable tail latency

Weaknesses

•Young project; ecosystem maturity and connector support are still growing
•No built-in clustering in the open-source version — the cloud offering handles horizontal scaling
•Write patterns that bypass the optimized append path can degrade performance significantly

•Cassandra compatibility is not 100%; subtle behavioral differences can surface during migration
•Smaller community and ecosystem than Apache Cassandra for tooling and integrations
•Self-managed deployment requires Cassandra operational expertise plus ScyllaDB-specific knowledge

Weaknesses

•Young project; ecosystem maturity and connector support are still growing
•No built-in clustering in the open-source version — the cloud offering handles horizontal scaling
•Write patterns that bypass the optimized append path can degrade performance significantly

•Cassandra compatibility is not 100%; subtle behavioral differences can surface during migration
•Smaller community and ecosystem than Apache Cassandra for tooling and integrations
•Self-managed deployment requires Cassandra operational expertise plus ScyllaDB-specific knowledge

License

Apache-2.0

AGPL-3.0 (Community)

License

Apache-2.0

AGPL-3.0 (Community)

Install

pip install questdb

pip install scylla-driver

Install

pip install questdb

pip install scylla-driver

Rating

★ 4.5

Rating

★ 4.5

Key Features

QuestDB

1High-performance time-series SQL database with columnar storage
21.6 million rows per second single-node ingestion via InfluxDB line protocol
3SQL extensions: SAMPLE BY, LATEST ON, and ASOF JOIN for time-series
4PostgreSQL wire protocol compatibility for standard Python drivers
5Built-in web console with SQL editor and charting

ScyllaDB

1Cassandra-compatible NoSQL database written in C++ for 10x lower latency
2Shard-per-core architecture eliminates cross-core synchronization overhead
3Drop-in Cassandra replacement — uses the same CQL and drivers
4Compaction strategies optimized for write-heavy workloads
5ScyllaDB Cloud for fully managed deployment on AWS, GCP, and Azure

How Python Data Engineers Use These Tools