Particularly for indexing issues, it is useful to provide a database backup to Support so that they can reproduce the issue.

However, some of your content may be private, so to anonymise it:

1) Take the mysql dump of your confluence database:

mysqldump -u username -ppassword database_name > FILE.sql

2) Load it into a test database

mysql -u username -ppassword test_database < FILE.sql

3) Run the following query against your test database:

update BODYCONTENT set BODY='a';
update USERS set PASSWORD='x61Ey612Kl2gpFL56FT9weDnpSo4AV8j8+qx2AuTHdRyY036xxzTTrw10Wq3+4qQyB+XURPWx1ONxp3Y3pB37A=='

This will update all content on pages to "a"

This only anonymizes the data on pages, comments and blog posts and user passwords. It does not anonymise the titles of pages, usernames or labels.