Reduce database size - turn off revisions

Hi

I have recently set up my first Drupal website. I migrated a news site to Drupal using the migrate module. It worked great but after the site has been up for little over a week the database has grown to over 1gb. There is 5000 articles in the database, but still, should it be that big?

In phpmyadmin, I can see the biggest tables are:
- search_index (200mb)
- cache_field (164mb)
- field_revision_body(136mb)
- field_data_body (136mb)

I'm not sure why the field_revision_body table even has data, I haven't turned on revisioning. Would it be safe to truncate this table? Maybe even drop it?

Is it normal for a Drupal database to be this large with 5000 articles/nodes?

Best Regards
Attensa