SQLite3 query slow in Swift - sql

Question

The following SQLite3 statement is very slow in my Swift-Code (see below)
Any idea why ??
Currently, it takes approx 30 seconds from breakpoint-1 to breakpoint-2
// .. breakpoint-1
while ((sqlite3_step(statement) == SQLITE_ROW) {
// .. breakpoint-2
}
My SQLite-db is 450 MB in size and the query is quite complex.
I am simply not sure if this "while-loop" cannot be made faster somehow ??
Here is the Query:
var query1: String = ""
query1 =
"""
SELECT DISTINCT st.departure_time as time, t.trip_headsign, r.route_desc, t.trip_id
FROM stops s
INNER JOIN calendar c ON t.service_id = c.service_id
INNER JOIN stop_times st ON st.stop_id = s.stop_id
INNER JOIN trips t ON t.trip_id = st.trip_id
INNER JOIN routes r ON r.route_id = t.route_id
WHERE c.\(weekDay) = 1
AND st.departure_time > "\(departureTime)"
AND st.stop_id LIKE '\(stop_id)%'
AND s.stop_name <> t.trip_headsign
ORDER BY st.departure_time ASC
LIMIT 80
"""
Also, after maddy's input, I did create a new DB - this time "indexed" (see on which columns below..) . After indexing - the size of the DB increased to double its original size.
But with the above query and the newly indexed DB, the speed is unfortunately still identically slow (> 30 sec).
How would I need to change the query after having an "indexed" DB ???
How can I increase query-speed ???
These are the indexed columns:
CREATE INDEX departure_time_IDX ON stop_times(departure_time);
CREATE INDEX stop_times_id_IDX ON stop_times(stop_id);
CREATE INDEX stop_times_trip_id_IDX ON stop_times(trip_id);
CREATE INDEX stop_name_IDX ON stops(stop_name);
CREATE INDEX stop_id_IDX ON stops(stop_id);
CREATE INDEX trip_headsign_IDX ON trips(trip_headsign);
CREATE INDEX trip_id_IDX ON trips(trip_id);
CREATE INDEX trip_route_id_IDX ON trips(route_id);
CREATE INDEX service_id_IDX ON trips(service_id);
CREATE INDEX route_desc_IDX ON routes(route_desc);
CREATE INDEX route_id_IDX ON routes(route_id);
CREATE INDEX cal_service_id_IDX ON calendar(service_id);
CREATE INDEX monday_IDX ON calendar(monday);
CREATE INDEX tuesday_IDX ON calendar(tuesday);
CREATE INDEX wednesday_IDX ON calendar(wednesday);
CREATE INDEX thursday_IDX ON calendar(thursday);
CREATE INDEX friday_IDX ON calendar(friday);
CREATE INDEX saturday_IDX ON calendar(saturday);
CREATE INDEX sunday_IDX ON calendar(sunday);
Here is the EXPLAIN QUERY PLAN
I have the query down to 3 seconds if I eliminate the INNER JOIN's of trips and routes. Of course, I need those two for the result I expect out of this. But at least it shows that the INNER JOIN's of those two extra tables are slowing things down.
Also, it has to be noticed that stop_times is the biggest table of all !
(then comes trips - and the others are all smaller...)
The 3-sec query looks like this :
var faster_query: String = ""
faster_query =
"""
SELECT DISTINCT st.departure_time as time
FROM stops s
INNER JOIN stop_times st ON st.stop_id = s.stop_id
WHERE st.departure_time > "19:51:00"
AND st.stop_id LIKE '8505000%'
ORDER BY st.departure_time ASC
LIMIT 80
"""
The EXPLAIN QUERY PLAN for this faster_query looks like this:
Here is the whole code for the SQLite3 query
// Open SQLite database
var db: OpaquePointer? = nil
if let path = self.departure_filePath?.path {
if sqlite3_open(path, &db) == SQLITE_OK {
var statement: OpaquePointer? = nil
// Run SELECT query from db
if sqlite3_prepare_v2(db, query1, -1, &statement, nil) == SQLITE_OK {
// Loop through all results from query1
// .. breakpoint-1
while ((sqlite3_step(statement) == SQLITE_ROW) {
// .. breakpoint-2
let ID = sqlite3_column_text(statement, 0)
if ID != nil {
IDString = String(cString:ID!)
} else {
print("ID not found", terminator: "")
return nil
}
}
}
}
}