DATA_VERSION

The SQLITE_FCNTL_DATA_VERSION opcode is used to detect changes to a database file. The argument is a pointer to a 32-bit unsigned integer. The "data version" for the pager is written into the pointer. The "data version" changes whenever any change occurs to the corresponding database file, either through SQL statements on the same database connection or through transactions committed by separate database connections possibly in other processes. The sqlite3_total_changes() interface can be used to find if any database on the connection has changed, but that interface responds to changes on TEMP as well as MAIN and does not provide a mechanism to detect changes to MAIN only. Also, the sqlite3_total_changes() interface responds to internal changes only and omits changes made by other database connections. The PRAGMA data_version command provides a mechanism to detect changes to a single attached database that occur due to other database connections, but omits changes implemented by the database connection on which it is called. This file control is the only mechanism to detect changes that happen either internally or externally and that are associated with a particular attached database.