Sample code showing how to minimise unused space in a blob-heavy SQLite3 database to be distributed. If a blob could cause unused space, split it in two before distribution and re-join it at the destination.

The blobpack program transforms a database with this schema

create table blobs (
    id integer primary key,
    val blob
);

into one with this schema

create table frags (
    id integer primary key,
    val blob not null
);

create table splits (
    id integer primary key,
    head integer references frags,
    tail integer references frags
);

If the source val is NULL, both head and tail are NULL. If a blob doesn't need splitting, tail is NULL.

The blobunpack program performs the inverse transformation.