Storage Architecture
The underlying storage architecture—whether it is a Log-Structured Merge-Tree (LSM-Tree) like RocksDB or a B-Tree structure like SQLite—determines how the database handles writes and reads. Applications requiring high write throughput often benefit from LSM-based engines, whereas applications requiring complex relational queries are better served by B-Tree or columnar formats like DuckDB.
ACID Compliance
Atomicity, Consistency, Isolation, and Durability (ACID) are critical for data integrity. Even in an embedded environment, you must ensure that the database can recover gracefully from application crashes or power failures. Look for robust write-ahead logging (WAL) implementations that prevent data corruption during unexpected interruptions.
Footprint and Resource Usage
Because embedded databases consume the host application's memory and CPU resources, the library size and runtime overhead are vital. For embedded systems or IoT hardware with limited RAM, tools like Berkeley DB or highly optimized key-value stores are often chosen for their minimal footprint.
API Flexibility and Language Support
An embedded database is only as useful as its integration capabilities. Evaluate whether the tool provides native bindings for your primary development stack (e.g., C++, Java, Python, or Rust). Well-documented APIs ensure that your developers can map their application data models to the database schema without excessive boilerplate code.