SQLite Forum

integer primary key and index table
Did you read <https://sqlite.org/rowidtable.html>?

>  if col is integer primary key,does this select statement do a binary search in index-table for rowid first

No.  The rowid is the key to the table row in the b-tree.  In the case you describe above the rowid is used to traverse the table b-tree directly.

Additional indexes contain the "key columns" and the rowid.  The key columns are used to traverse the index b-tree to find the rowid of the row in the underlying table, and then that rowid is used directly to traverse the table b-tree to locate the row data.

See also <https://sqlite.org/fileformat.html>