gistfile1.md

1. Migrate the db.

2. Copy 'temp_session.dump' from the 'ttm-utilities' S3 bucket.

3. Restore the dump to the master shard: (Ignore any warnings about the zmance user ... nailed it.)

   pg_restore -U -h -p -d -t tmp_session_last_attempt_date temp_session.dump

4. Add an index to the temp table:

   CREATE INDEX ON tmp_session_last_attempt_date (session_id);

5. Run this on the master shard: (may take up to an hour)

   UPDATE student_sessions SET last_attempt_date = t.last_attempt_date FROM tmp_session_last_attempt_date t WHERE student_sessions.id = t.session_id;

6. Drop the temp table from the master shard:

   DROP TABLE tmp_session_last_attempt;