*** 97,100 **** --- 97,101 ---- SQLite (3.2.5) : 819,200 bytes Firebird (1.5.2.4731 embedded) : 8,736,768 bytes ----- + IIRC, as of 3.1 SQLite introduced an optimization that would result in the rows of a table consisting only of a single integer primary key column being stored entirely in the index (all SQLite tables have a "rowid" index). That may account for the magnitude of the difference.