SQLite Forum

Understanding memory allocation behavior of SQLite
You will also not that if your chema is thus:

CREATE TABLE table_name 
   col1 INTEGER, 
   col2 INTEGER, 
   col3 INTEGER, 
   col4 INTEGER, 
   col5 STRING, 
   PRIMARY KEY(col1, col2, col3)
CREATE INDEX index_name ON table_name (col4, col5)

then in addition to all the fiddle-faddle trying to "convert" `col5` from however you present it into a REAL or INTEGER (since you have indicated a preference for storage as an INTEGER, then if that does not work, as REAL, and if that does not work, then "as presented") you are also storing the contents of EVERY ROW TWICE.

Once in the WITHOUT ROWID B-Tree and then yet again in the index_name B-Tree.  The only difference between the two B-Tree's being the `key` and the `payload`, but all records are duplicated completely.

Since it is not possible to insert in-order, then no matter what you do you will be requiring TWO B-Tree rebalance operations FOR EACH ROW (batch) inserted.

Perhaps you need to re-visit your "design".