Example query: https://quarry.wmflabs.org/query/49456

SELECT * FROM `logging` 
LEFT JOIN `comment`
ON `comment`.comment_id=logging.log_comment_id
WHERE log_type="thanks"
LIMIT 10;

Here in the logging table, a thank records the in the field log_actor of the thank-giver, and the log_page and log_title as the thank-receiver. The problem is to how do we incorporate the new information, mostly a revision id. There are 2 design options:

Option 1. add the revision_id in the log_params

• cons: error-prone, can't be indexed and used for faster query
• pros: fully backward compatible, not requiring a schema change, no downtime needed, smaller database size

Option 2. create a separate log_revision_id field,

• cons: requiring a schema change, potential read-only down time, bigger database size
• pros: much clearer, can be indexed, faster for query and other action.

Option 3. use`comment_id` as the revision_id for thanks log.

• cons and pros: similar to Option 1 except it can be indexed, but pretty hacky and can cause problem when joined with comment table.

I suggest go with the Option 2.