MariaDB/MySQL writer not ignoring calculated columns

I’m not 100% sure on this but it could be related to Bulk Insert. Bulk insert is waaay faster but I did read that it invalidates foreign fey constraints. Can you try turning off Bulk insert? 

If not there could be a creative way to run some SQL before and after write to somehow disable/drop the column and then recalculate the values after the insert - This might not be a valid solution for you though. 

What happens if you remove the attribute Checksum from the features just before it enters the writer using an AttributeRemover? I think this is your issue.

Have had a simular issue writing to a postgres db where columns in my table got updated while they were not defined as attributes in the writer. I expected the writer to only update the columns defined in the writer, but this turned out to be different.

The MariaDB/MySQL writer doesn’t have an explicit bulk insert parameter like the SQL Server writer, so I tried setting the “operations per SQL statement” setting on the table to 1. Unfortunately it gets the same error, so I don’t think that’s it.

I’m not actually creating the Checksum in the workflow at all - the AttributeManager immediately before the writer doesn’t have any column similar to it coming out. It’s only defined in the database.

In case it’s helpful to others, the option I went with here was leaving the Checksum column off the table entirely, and instead creating a view in the database to layer on the Checksum. The view’s pretty simple, it’s basically:

SELECT s.*, UNHEX(SHA2(..., 512)) AS `Checksum` FROM <table> s

And that does the trick. The downside is another database object; the upside is FME is perfectly happy and the additional object is pretty simple.