Can I read and write to a SQLite database concurrently from multiple connections?

Question

I have a SQLite database that is used by two processes. I am wondering, with the most recent version of SQLite, while one process (connection) starts a transaction to write

Answer 1

SQLite3 explicitly allows multiple connections:

(5) Can multiple applications or multiple instances of the same application access a single database file at the same time?

Multiple processes can have the same database open at the same time. Multiple processes can be doing a SELECT at the same time. But only one process can be making changes to the database at any moment in time, however.

For sharing connections, use SQLite3 shared cache:

Starting with version 3.3.0, SQLite includes a special "shared-cache" mode (disabled by default)

In version 3.5.0, shared-cache mode was modified so that the same cache can be shared across an entire process rather than just within a single thread.

5.0 Enabling Shared-Cache Mode

Shared-cache mode is enabled on a per-process basis. Using the C interface, the following API can be used to globally enable or disable shared-cache mode:

int sqlite3_enable_shared_cache(int);

Each call sqlite3_enable_shared_cache() effects subsequent database connections created using sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2(). Database connections that already exist are unaffected. Each call to sqlite3_enable_shared_cache() overrides all previous calls within the same process.