The page table has a page_content_model column as VARBINARY(32) DEFAULT NULL.

There is already the content_models table with all possible values (via NameTableStore).
So the column could be replaced with a shorter model id column as SMALLINT UNSIGNED to save some space on the page table (up to 29 bytes per row, the most used value is wikitext, so this only about 7 bytes - 8 bytes for chars plus 1 byte for the length minus 2 bytes for smallint).

This may not needed when the column is dropped T230607: stop using page_content_model, but should/could be done otherwise.