I have a linked table id_group | id_user. Every time I add a one or more users to a group I
DELETE all the links and
INSERT the users again including the new one(s). This is how the framework of the application works.
From time to time some groups lose all the users they had, except the new ones, which are inserted.
The primary index of the table is the pair
id_group - id_user.
I cannot reproduce this through a query, but the client has complained multiple times and there's an issue no doubt.
I could explain this if the table was
innoDB with the
DELETE locking the index and the
INSERT not being able to add that pair again, however this is a
myISAM table and
myISAM locks the entire table during