Shotwell / Set event's key photos by max raiting (put it to ~/.shotwell/data/update-key-events-photos-by-rating.sh)

update-key-events-photos-by-rating.sh

#!/usr/bin/env bash

function sql() {
	local sql=$1
	sqlite3 photo.db "$sql"
}

function go_to_current_directory() {
	cd "$(dirname "$0")"
}

function find_all_active_event_ids() {
	sql 'SELECT DISTINCT event_id FROM PhotoTable'
}

function find_best_photo_id_by_event() {
	local event_id=$1
	sql "SELECT id FROM PhotoTable WHERE event_id = $event_id ORDER BY rating DESC, exposure_time LIMIT 1"
}

function update_event_key_photo() {
	local event_id=$1
	local photo_id=$(find_best_photo_id_by_event $event_id)
	local thumb_id=$(printf '%s%016x' 'thumb' $photo_id)
	echo "Updating event #$event_id"
	sql "UPDATE EventTable SET primary_source_id = '$thumb_id' WHERE id = $event_id"
}

function main() {
	go_to_current_directory

	for event_id in $(find_all_active_event_ids)
	do
		update_event_key_photo $event_id
	done
}

main

Needs improvement as update_event_key_photo is a SQL that opens DB/updates it in loop.