Redmine

There is no inherent limit on the number of issues you can have in a Redmine database. If your hardware is capable enough (*which is quite likely), 1 million issues should not be an issue.

Note though that some usages may still be more taxing than others. Some "expensive" usages include:

• Large issues trees with roughly more than 50 issues per tree. Large trees can take a while to update and may even cause timeouts. Try to organize your issues in smaller trees.
• Lots of trackers or statuses (> 100 each) can cause slowdowns on some views.
• Large numbers of members in a project (hundreds of users). As above, this may cause slowdowns on some views where the entire user list is rendered

Apart from that, Redmine should be quite capable of dealing with large numbers or projects, issues and users.

Thanks for your answer