Using SQLite

Application Cache

SQLite is capable of creating databases that are held entirely in memory. This is extremely useful for creating small, temporary databases that require no permanent storage.

In-memory databases are often used to cache results pulled from a more traditional RDBMS server. An application may pull a subset of data from the remote database, place it into a temporary database, and then process multiple detailed searches and refinements against the local copy. This is particularly useful when processing type-ahead suggestions, or any other interactive element that requires very quick response times.

Temporary databases can also be used to index and store nearly any type of inter-linked, cross-referenced data. Rather than designing a set of complex runtime data structures which might include multiple hash tables, trees, and cross-referenced pointers, the developer can simply design an appropriate database schema and load the data into the database.

While it might seem odd to execute SQL statements in order to extract data from an in-memory data structure, it is surprisingly efficient and can reduce development time and complexity. A database also provides an upgrade path, making it trivial to grow the data beyond the available memory or persist the data across application runs, simply by migrating to an on-disk database.