In Sqlite3, Write-Ahead-Logging mode allows one process to read a table, while another is writing to it. It doesn't say anything about one process writing and another deleting/updating.
Is this possible in Sqlite3?
DELETE and/or an
UPDATE are both writes!
Only one process can write at any one time - that is an
UPDATE or a
DELETE at the same time. You can
SELECT with as many processes as you like, but only one of the others at a time!