Information originally from djcarr in bug #8407 here

After more investigation I've come up with a set of good guidelines for dumping and importing fairly large mantis databases. I'll post them here in case they can help someone else.

mysqldump --host=*** --user=*** --password=*** --hex-blob --skip-extended-insert --result-file=mantisdb_files.sql mantisdb mantis_bug_file_table

Why? Because this one table can get very big and MySQL Server cannot reimport scripts more than about 50MB. So you can then split this table dump into multiple smaller files if needed.

mysqldump --host=*** --user=*** --password=*** --skip-extended-insert --ignore-table=mantisdb.mantis_bug_file_table --result-file=mantisdb.sql mantisdb 
mysql --host=*** --user=*** --password=*** newmantisdb < mantisdb_files.sql
mysql --host=*** --user=*** --password=*** newmantisdb < mantisdb.sql

Do NOT use the MySQL Query Browser GUI to import - use the command line as above. The Query Browser chokes badly on the many '/ escapings that mysqldump places in the bug text and descriptions.