We are using an external tool to develop JIRA reports.
This tool connects directly to the database to generate reports.
It works fine except for reports that are using rules based on the history of changes.
In fact, the way you are storing changes in the changeitem table is not suitable and not generic enough.
You are storing only strings.

2 examples :

• Regarding the way you are qtoring dates: you are storing them using the screen format. If this format changes during the life of JIRA, we will have several date formats in the history. Then, it's very difficul for our reporting tool to analyse the dates and make differences...
• Regarding the custom fields:
• you are storing the values as string.
• You are storing only the name of the custom fields and not their ID. So, if the name changes, the external reporting tool will be unable to get the history of this field.

So, you should change the way you are storing changes by :

• storing old values and new values like the CUSTOMFIELDVALUE does
• storing the ID of custom fields and not only the name.

Today, we can answer to the need of users that want to have complex reports, but we know that if some custom field names change, the reports won't work anymore...

Do you think you could change this in a future version ?