Adding a SQL column to a table duplicates the table

Question

On a mySQL database, a strange phenomenon appeared. When I try to add a column to a table, the column is added, but the table is duplicated afterwards. It keeps duplicating tables if we try to add other columns and I do not know how to fix it or where it could come from. The SQL DB is hosted on Azure

Here is what the situation is like before trying to add a column:

SHOW tables;

('annotations',)
('dicoms',)
('image',)
('patient',)
('procedure_biopsy',)
('series',)

DESCRIBE annotations;

('nb_lesions', 'int(11)', 'YES', '', None, '')
('id_annotation', 'int(11)', 'NO', 'PRI', None, 'auto_increment')
('id_annotator', 'varchar(50)', 'YES', '', None, '')
('id_annotation_request', 'int(11)', 'YES', '', None, '')
('comments_to_annotator', 'text', 'YES', '', None, '')
('status', 'varchar(50)', 'YES', '', None, '')
('location_output', 'varchar(50)', 'YES', '', None, '')
('date_saved', 'date', 'YES', '', None, '')
('version', 'varchar(50)', 'YES', '', None, '')
('nb_bounding_boxes', 'int(11)', 'YES', '', None, '')
('purpose', 'varchar(50)', 'YES', '', None, '')
('id_image', 'int(11)', 'YES', '', None, '')
('type_annotation', 'varchar(50)', 'YES', '', None, '')

Now, if I send this request:

ALTER TABLE annotations ADD test_column varchar(50);

the requests performs successfully, and with "DESCRIBE annotations;", we get:

('nb_lesions', 'int(11)', 'YES', '', None, '')
('id_annotation', 'int(11)', 'NO', 'PRI', None, 'auto_increment')
('id_annotator', 'varchar(50)', 'YES', '', None, '')
('id_annotation_request', 'int(11)', 'YES', '', None, '')
('comments_to_annotator', 'text', 'YES', '', None, '')
('status', 'varchar(50)', 'YES', '', None, '')
('location_output', 'varchar(50)', 'YES', '', None, '')
('date_saved', 'date', 'YES', '', None, '')
('version', 'varchar(50)', 'YES', '', None, '')
('nb_bounding_boxes', 'int(11)', 'YES', '', None, '')
('purpose', 'varchar(50)', 'YES', '', None, '')
('id_image', 'int(11)', 'YES', '', None, '')
('type_annotation', 'varchar(50)', 'YES', '', None, '')
('test_column', 'varchar(50)', 'YES', '', None, '')

But the problem comes when we try to run "SHOW tables;" as it returns:

('annotations',)
('annotations',)
('dicoms',)
('image',)
('patient',)
('procedure_biopsy',)
('series',)

The table annotation is duplicated.

I also tried to check with dgForge and dataGrip how the data looks like, and I get 2 completely different results from those database explorers.

• With dgForge studio 2020 for mySQL, I see duplicated tables and other columns of the table are all duplicated. (but if we try to look at the data itself, columns does not seem duplicated)
• With dataGrip, I do not see any duplicated tables or duplicated columns anywhere

I really do not understand what's happening here. Any idea of were this type of issue could come from or what could be done to fix this strange behavior? Thank you very much for your help anyways !

Answer 1

Quick workaround for the problem: Restart your MySQL Azure DB and the duplicates are gone. InnoDB has a healing mechanism during restart.

It is not solving the problem, but at least the duplicates are gone, and you can work with the DB.

For the problem itself, after doing a lot of research with my technical guy, we think it is a Microsoft Azure issue and reported it to Microsoft. I will post the answer as soon as I have one.

Answer 2

According to Microsoft this issue seems to be a known issue due to last March deployment. In order to solve the issue, Microsoft has changed the server parameter dir_cache_fine_grained_enabled = OFF, which is not exposed to customers

This change will only take effect after you reboot the server.

After restarting my Azure DB servers, the issue is not present anymore!