I’ve been exploring the enwiki database. I can find the page row for [[Iron]]

MariaDB [enwiki_p]> select page_title from page where page_id = 14734;
+------------+
| page_title |
+------------+
| Iron |
+------------+

It looks like it has the right number of revisions:

MariaDB [enwiki_p]> select count(*) from revision where rev_page = 14734;
+----------+
| count(*) |
+----------+
| 5560 |
+----------+

But, all of the rev_text_ids are 0

MariaDB [enwiki_p]> select rev_text_id from revision where rev_page = 14734 and rev_text_id != 0;
Empty set (0.02 sec)

The schema description seems pretty straight-forward. What am I not understanding?