I have a database with many tables which can be joined by indexed keys (primary and foreign keys). Some tables are transaction tables which have an autoincremental primary key just to define a ID for each transaction.
To use this database and process the data (cleansing, adding new columns) I copy the database. The processes on the new database (updates, inserts) are quite complex. I index columns where it makes sense but I don't want to index columns which I don't need due to reason of performance.
Now, I come to the point: there are several huge transactions tables which have been defined from the original database as primary key but which are not used as key for joining. I would like to remove these primary keys (not the column but just: ALTER TABLE trans DROP PRIMARY KEY) to avoid too many indexed columns. Is there any reason not to remove index on a primary key?
If this question is dependent on RDBMS: I use MySQL/MariaDB.