From T328032#8936008 (with small tweaks):

The current schema should be updated:

• We should store the time of first answer, probably in the ce_participants table
• We may have to store whether your answers have already been aggregated (e.g., to prevent you from answering again), if this can't be inferred from the other data.

Update 2023-06-27: we decided that we're going to store whether answers were already aggregated regardless of the fact that this information can be derived from other things. We're doing this for simplicity, and because space isn't a concern. Also, we will store it as a timestamp (instead of a boolean) in case we need it later.

Acceptance criteria

• A new column is added to ce_participants to store the timestamp (or null) when the participant answered the questions for the first time
• A new column is added to ce_participants to store the timestamp (or null) when the participant's answers were aggregated
• The new columns should be created in beta
• The new columns should be created in production