Database

This depends on the database you are using. If you have trouble, read the documentation for your database or ask your database admin.

MySQL

If you use MySQL table type MyISAM (which is default) and have deleted a large part of a table or if you have made many changes to a table with variable-length rows (tables that have VARCHAR, BLOB, or TEXT columns) you need to defragment the datafile (tables) by "optimize" command.

You should try it if mysqld needs a lot of your CPU time. Optimize table ticket, ticket_history and article.
mysql> optimize table ticket;
mysql> optimize table ticket_history;
mysql> optimize table article;