lukas-mi / kvt-store

Key Value Timestamp store POC

kvt-store

Key Value Timestamp store POC

Prerequisites:

• sbt for building Scala code

Run application on localhost:8080:

• sbt run

Run tests:

• sbt test

Implementations:

• InMemoryKVTStore: an in memory store based on a concurrent map where each key is associated with an ordered map structure with timestamp as the key (implemented as red-black tree)
• SQLiteKVTStore: a persistent store backed by SQLite embedded DB. Queries under the hood:
  • Table definition:

      CREATE TABLE IF NOT EXISTS kvt_store (
          `key` VARCHAR(255) NOT NULL,
          `value` VARCHAR(255) NOT NULL,
          `timestamp` TIMESTAMP NOT NULL,
          PRIMARY KEY (`key`, `timestamp`)
      );
    

  • For put operations:

      INSERT INTO kvt_store (`key`, `value`, `timestamp`)
          VALUES(?, ?, ?)
          ON CONFLICT(`key`, `timestamp`) DO UPDATE SET
              `value`=excluded.`value`;
    

  • For get operations:

      SELECT value
      FROM kvt_store
      WHERE key = ?
          AND timestamp <= ?
      ORDER BY timestamp DESC
      LIMIT 1
    

TODO:

• Add tests for API
• Alternative implementation for a persistent store (e.g. with Redis)