Optimised getLastSeenEventTimestamp function

[ronaldlangeveld]

ref ENG-832

depends on #20118 for migration column in emails table, will rebase accordingly.

• every time handleDelivered, handleOpened and handlePermanentFailed fires, it will also update the latest_event_timestmap in the email table.
• we then conditionally remove 3 email queries in favour of 1 query that will get the latest event timestamp
• added additional tests

[github-actions]

It looks like this PR contains a migration 👀
Here's the checklist for reviewing migrations:

General requirements

• Satisfies idempotency requirement (both up() and down())
• Does not reference models
• Filename is in the correct format (and correctly ordered)
• Targets the next minor version
• All code paths have appropriate log messages
• Uses the correct utils
• Contains a minimal changeset
• Does not mix DDL/DML operations

Schema changes

• Both schema change and related migration have been implemented
• For index changes: has been performance tested for large tables
• For new tables/columns: fields use the appropriate predefined field lengths
• For new tables/columns: field names follow the appropriate conventions
• Does not drop a non-alpha table outside of a major version

Data changes

• Mass updates/inserts are batched appropriately
• Does not loop over large tables/datasets
• Defends against missing or invalid data
• For settings updates: follows the appropriate guidelines

[sagzy]

LGTM 👍

[sagzy]

Maybe worth explaining why we need to convert to a Date here?

// SQLite returns a string instead of a Date

[sagzy]

I'm guessing we're keeping the old logic to smoothen the rollout, as existing emails won't have the latest_event_timestamp field. Shall we make a note to clean this up in a couple of weeks from now?

[sagzy]

You could also return early here, to separate the new logic from the old one, e.g.

if (maxTimestamp) {
    if (!(maxTimestamp instanceof Date)) {
        maxTimestamp = new Date(maxTimestamp);
     }
              
     return maxTimestamp;
}


// Legacy logic

...

[ronaldlangeveld]

Yes correct, I'll add a note in the comments.