3

I'm trying to play with a GTFS database, namely the one provided by the RATP for Paris and its suburbs.

The set of data is huge. The stop_times table has 14 million rows.

Here's the tables schemas: https://github.com/mauryquijada/gtfs-mysql/blob/master/gtfs-sql.sql

I'm trying to get the most efficient way to get the available routes at a specific location. As far as I understand the GTFS spec, here are the tables and their links from my data (lat/lon) to the routes:

stops      | stop_times     | trips      | routes
-----------+----------------+------------+--------------
lat        | stop_id        | trip_id    | route_id
lon        | trip_id        | route_id   |
stop_id    |                |            |

I have compiled what I want in three steps (actually the three links we have between the four tables above), published under this gist for clarity: https://gist.github.com/BenoitDuffez/4eba85e3598ebe6ece5f

Here's how I created this script.

I have been able to quickly find all the stops within a walking distance (say, 200m) in less than a second. I use:

$ . mysql.ini && time mysql -h $host -N -B -u $user -p${pass} $name -e "SELECT stop_id, (6371000*acos(cos(radians(48.824699))*cos(radians(s.stop_lat))*cos(radians(2.3243)-radians(s.stop_lon))+sin(radians(48.824699))*sin(radians(s.stop_lat)))) AS distance
FROM stops s
GROUP BY s.stop_id
HAVING distance < 200
ORDER BY distance ASC" | awk '{print $1}'
3705271
4472979
4036891
4036566
3908953
3908755
3900765
3900693
3900607
4473141
3705272
4472978
4036892
4036472
4035057
3908952
3705288
3908814
3900832
3900672
3900752
3781623
3781622

real    0m0.797s
user    0m0.000s
sys     0m0.000s

Then, getting all the stop_times later today (with stop_times.departure_time > '``date +%T``') takes a lot of time:

"SELECT trip_id
 FROM stop_times
 WHERE
     stop_id IN ($stops) AND departure_time >= '$now'

 GROUP BY trip_id"

With $stops containing the list of stops obtained from the first step. Here's an example:

$ . mysql.ini && time mysql -h $host -N -B -u $user -p${pass} $name -e "SELECT stop_id, (6371000*acos(cos(radians(
FROM stops s
GROUP BY s.stop_id
HAVING distance < 200
ORDER BY distance ASC" | awk '{print $1}'
3705271
4472979
4036891
4036566
3908953
...
9916360850964321
9916360920964320
9916360920964321

real    1m21.399s
user    0m0.000s
sys     0m0.000s

There are more than 2000 lines in this result.

My last step was to select all routes that match these trip_ids. It's quite easy, and rather fast:

$ . mysql.ini && time mysql -h $host -u $user -p${pass} $name -e "SELECT r.id, r.route_long_name FROM trips t, routes r WHERE t.trip_id IN (`cat trip_ids | tr '\n' '#' | sed -e 's/##$//' -e 's/#/,/g'`) AND r.route_id = t.route_id GROUP BY t.route_id"
+------+-------------------------------------------------------------------------+
| id   | route_long_name                                                         |
+------+-------------------------------------------------------------------------+
|  290 | (PLACE DE CLICHY <-> CHATILLON METRO) - Aller                           |
|  291 | (PLACE DE CLICHY <-> CHATILLON METRO) - Retour                          |
|  404 | (PORTE D'ORLEANS-METRO <-> ECOLE VETERINAIRE DE MAISON-ALFORT) - Aller  |
|  405 | (PORTE D'ORLEANS-METRO <-> ECOLE VETERINAIRE DE MAISON-ALFORT) - Retour |
|  453 | (PORTE D'ORLEANS-METRO <-> LYCEE POLYVALENT) - Retour                   |
|  457 | (PORTE D'ORLEANS-METRO <-> LYCEE POLYVALENT) - Retour                   |
|  479 | (PORTE D'ORLEANS-METRO <-> VELIZY 2) - Retour                           |
|  810 | (PLACE DE LA LIBERATION <-> GARE MONTPARNASSE) - Aller                  |
|  989 | (PORTE D'ORLEANS-METRO) - Retour                                        |
| 1034 | (PLACE DE LA LIBERATION <-> HOTEL DE VILLE DE PARIS_4E__AR) - Aller     |
+------+-------------------------------------------------------------------------+

real    0m1.070s
user    0m0.000s
sys     0m0.000s

With here the file trip_ids containing the 2k trip IDs.

How can I get this result faster? Is there a better way to crawl through the data rather than the stops>stop_times>trips>routes path I have taken?

The total time here is around 30s for actually ONE 'query': "What are the routes available 200m from this location?". That's too much...

4

3 回答 3

4

简短的回答是：使用表连接和索引。

这是更长的答案：

您在这里有正确的想法，并且您对表格如何相互关联的理解是正确的。但是，通过要求 DBMS 匹配列表中的字段值（使用WHERE...IN）而不是将表连接在一起，您需要它做的工作比它需要做的要多得多。

您真正想要做的是将所有这些作为单个查询执行，使用JOIN子句将表链接在一起。试试这个，它还加入了calendars和calendar_dates表以将结果限制为仅今天实际运行的路由：

SELECT DISTINCT r.id, r.route_long_name
  FROM (SELECT s.stop_id, (6371000 *
          acos(cos(radians(48.824699)) * cos(radians(s.stop_lat)) *
          cos(radians(2.3243) - radians(s.stop_lon)) +
          sin(radians(48.824699)) * sin(radians(s.stop_lat)))) AS distance
          FROM stops AS s) AS i_s
  INNER JOIN stop_times AS st ON st.stop_id = i_s.stop_id
  INNER JOIN (SELECT trip_id, route_id FROM trips AS t
                INNER JOIN (SELECT service_id FROM calendars
                              WHERE start_date <= '2014-09-09'
                                AND end_date >= '2014-09-09'
                                AND tuesday = 1
                              UNION
                                SELECT service_id FROM calendar_dates
                                  WHERE date = '2014-09-09'
                                    AND exception_type = 1
                              EXCEPT
                                SELECT service_id FROM calendar_dates
                                  WHERE date = '2014-09-09'
                                    AND exception_type = 2) AS c
                   ON c.service_id = t.service_id) AS t_r
    ON t_r.trip_id = st.trip_id
  INNER JOIN routes AS r ON r.route_id = t_r.route_id
  WHERE st.departure_time > '$now'
    AND i_s.distance < 200;

这里INNER JOIN用于“添加”另一个表的列，仅包括与ON子句中的条件匹配的那些行。这应该比使用一个查询生成结果列表然后将其提供给下一个查询要快得多。

但是，为了获得更好的性能，您需要创建索引以防止 DBMS 必须线性扫描表。经验法则是为 aJOIN或WHERE子句中使用的每一列定义一个索引。以下是我定义的索引，您应该会发现它们使上述查询执行得相当好：

CREATE INDEX calendar_dates_date_exception_type_service_id_index
  ON calendar_dates (date, exception_type, service_id);

CREATE INDEX trips_service_id_trip_id_route_id_index
  ON trips (service_id, trip_id, route_id);

CREATE INDEX stop_times_trip_id_departure_time_stop_id_index
  ON stop_times (trip_id, departure_time, stop_id);

CREATE INDEX routes_route_id_index ON routes (route_id);

CREATE INDEX stops_stop_id_index ON stops (stop_id);
于 2014-09-09T18:35:02.213 回答
1

我使用的表模式完全错误，我应该自己构建它，或者至少在使用它之前对其进行分析。

这是一个更新的架构：

CREATE TABLE `agency` (
    transit_system VARCHAR(50) NOT NULL,
    agency_id VARCHAR(100),
    agency_name VARCHAR(255) NOT NULL,
    agency_url VARCHAR(255) NOT NULL,
    agency_timezone VARCHAR(100) NOT NULL,
    agency_lang VARCHAR(100),
    agency_phone VARCHAR(100),
    agency_fare_url VARCHAR(100),
    PRIMARY KEY (agency_id)
);

CREATE TABLE `calendar_dates` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    service_id VARCHAR(255) NOT NULL,
    `date` VARCHAR(8) NOT NULL,
    exception_type TINYINT(2) NOT NULL,
    KEY `service_id` (service_id),
    KEY `exception_type` (exception_type)    
);

CREATE TABLE `calendar` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    service_id VARCHAR(255) NOT NULL,
    monday TINYINT(1) NOT NULL,
    tuesday TINYINT(1) NOT NULL,
    wednesday TINYINT(1) NOT NULL,
    thursday TINYINT(1) NOT NULL,
    friday TINYINT(1) NOT NULL,
    saturday TINYINT(1) NOT NULL,
    sunday TINYINT(1) NOT NULL,
    start_date VARCHAR(8) NOT NULL, 
    end_date VARCHAR(8) NOT NULL,
    KEY `service_id` (service_id)
);

CREATE TABLE `fare_attributes` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    fare_id VARCHAR(100),
    price VARCHAR(50) NOT NULL,
    currency_type VARCHAR(50) NOT NULL,
    payment_method TINYINT(1) NOT NULL,
    transfers TINYINT(1) NOT NULL,
    transfer_duration VARCHAR(10),
    exception_type TINYINT(2) NOT NULL,
    agency_id INT(100),
    KEY `fare_id` (fare_id)
);

CREATE TABLE `fare_rules` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    fare_id VARCHAR(100),
    route_id VARCHAR(100),
    origin_id VARCHAR(100),
    destination_id VARCHAR(100),
    contains_id VARCHAR(100),
    KEY `fare_id` (fare_id),
    KEY `route_id` (route_id)
);

CREATE TABLE `feed_info` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    feed_publisher_name VARCHAR(100),
    feed_publisher_url VARCHAR(255) NOT NULL,
    feed_lang VARCHAR(255) NOT NULL,
    feed_start_date VARCHAR(8),
    feed_end_date VARCHAR(8),
    feed_version VARCHAR(100)
);

CREATE TABLE `frequencies` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    trip_id VARCHAR(100) NOT NULL,
    start_time VARCHAR(8) NOT NULL,
    end_time VARCHAR(8) NOT NULL,
    headway_secs VARCHAR(100) NOT NULL,
    exact_times TINYINT(1),
    KEY `trip_id` (trip_id)
);

CREATE TABLE `routes` (
    transit_system VARCHAR(50) NOT NULL,
    route_id VARCHAR(100),
    agency_id VARCHAR(50),
    route_short_name VARCHAR(50) NOT NULL,
    route_long_name VARCHAR(255) NOT NULL,
    route_type VARCHAR(2) NOT NULL, 
    route_text_color VARCHAR(255),
    route_color VARCHAR(255),
    route_url VARCHAR(255),
    route_desc VARCHAR(255),
    PRIMARY KEY (route_id),
    KEY `agency_id` (agency_id),
    KEY `route_type` (route_type),
    CONSTRAINT `agency_id` FOREIGN KEY (`agency_id`) REFERENCES `agency` (`agency_id`)
);

CREATE TABLE `shapes` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    shape_id VARCHAR(100) NOT NULL,
    shape_pt_lat DECIMAL(8,6) NOT NULL,
    shape_pt_lon DECIMAL(8,6) NOT NULL,
    shape_pt_sequence TINYINT(3) NOT NULL,
    shape_dist_traveled VARCHAR(50),
    KEY `shape_id` (shape_id)
);

CREATE TABLE `stops` (
    transit_system VARCHAR(50) NOT NULL,
    stop_id VARCHAR(255),
    stop_code VARCHAR(50),
    stop_name VARCHAR(255) NOT NULL,
    stop_desc VARCHAR(255),
    stop_lat DECIMAL(10,6) NOT NULL,
    stop_lon DECIMAL(10,6) NOT NULL,
    zone_id VARCHAR(255),
    stop_url VARCHAR(255),
    location_type VARCHAR(2),
    parent_station VARCHAR(100),
    stop_timezone VARCHAR(50),
    wheelchair_boarding TINYINT(1),
    PRIMARY KEY (stop_id),
    KEY `zone_id` (zone_id),
    KEY `stop_lat` (stop_lat),
    KEY `stop_lon` (stop_lon),
    KEY `location_type` (location_type),
    KEY `parent_station` (parent_station)
);

CREATE TABLE `trips` (
    transit_system VARCHAR(50) NOT NULL,
    route_id VARCHAR(100) NOT NULL,
    service_id VARCHAR(100) NOT NULL,
    trip_id VARCHAR(255),
    trip_headsign VARCHAR(255),
    trip_short_name VARCHAR(255),
    direction_id TINYINT(1), #0 for one direction, 1 for another.
    block_id VARCHAR(11),
    shape_id VARCHAR(11),
    wheelchair_accessible TINYINT(1), #0 for no information, 1 for at least one rider accommodated on wheel chair, 2 for no riders accommodated.
    bikes_allowed TINYINT(1), #0 for no information, 1 for at least one bicycle accommodated, 2 for no bicycles accommodated
    PRIMARY KEY (trip_id),
    KEY `route_id` (route_id),
    KEY `service_id` (service_id),
    KEY `direction_id` (direction_id),
    KEY `block_id` (block_id),
    KEY `shape_id` (shape_id),
    CONSTRAINT `route_id` FOREIGN KEY (`route_id`) REFERENCES `routes` (`route_id`),
    CONSTRAINT `service_id` FOREIGN KEY (`service_id`) REFERENCES `calendar` (`service_id`)
);

CREATE TABLE `stop_times` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    trip_id VARCHAR(100) NOT NULL,
    arrival_time VARCHAR(8) NOT NULL,
    arrival_time_seconds INT(100),
    departure_time VARCHAR(8) NOT NULL,
    departure_time_seconds INT(100),
    stop_id VARCHAR(100) NOT NULL,
    stop_sequence VARCHAR(100) NOT NULL,
    stop_headsign VARCHAR(50),
    pickup_type VARCHAR(2),
    drop_off_type VARCHAR(2),
    shape_dist_traveled VARCHAR(50),
    KEY `trip_id` (trip_id),
    KEY `arrival_time_seconds` (arrival_time_seconds),
    KEY `departure_time_seconds` (departure_time_seconds),
    KEY `stop_id` (stop_id),
    KEY `stop_sequence` (stop_sequence),
    KEY `pickup_type` (pickup_type),
    KEY `drop_off_type` (drop_off_type),
    CONSTRAINT `trip_id` FOREIGN KEY (`trip_id`) REFERENCES `trips` (`trip_id`),
    CONSTRAINT `stop_id` FOREIGN KEY (`stop_id`) REFERENCES `stops` (`stop_id`)
);

CREATE TABLE `transfers` (
    id INT(12) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    transit_system VARCHAR(50) NOT NULL,
    from_stop_id INT(100) NOT NULL,
    to_stop_id VARCHAR(8) NOT NULL,
    transfer_type TINYINT(1) NOT NULL,
    min_transfer_time VARCHAR(100)
);

我把xyz_id钥匙PRIMARY KEY放在他们自己的桌子上和FOREIGN KEY其他桌子上。
我仍然需要对这个架构进行一些优化。

现在这个查询可以在不到 1-5 秒的时间内完成：

SELECT
    s.stop_id,
    (6371000*acos(cos(radians(48.1128135))*cos(radians(s.stop_lat))*cos(radians(-1.6470705)-radians(s.stop_lon))+sin(radians(48.1128135))*sin(radians(s.stop_lat)))) AS distance,
    t.route_id,
    st.*,
    t.*,
    r.*,
    c.*

FROM stop_times st

LEFT JOIN stops s USING (stop_id)
LEFT JOIN trips t USING (trip_id)
LEFT JOIN routes r USING (route_id)

LEFT JOIN calendar c ON c.service_id = t.service_id 

where
    c.start_date <= 20140915
    and c.end_date >= 20140915
    and c.sunday = 1

    and st.departure_time > '15:00:00'

HAVING
    distance < 200

ORDER BY st.departure_time ASC
于 2014-09-12T10:54:31.357 回答
0

我只能告诉你，我用 SQL 尝试过同样的事情，而且花了很长时间，所以我不得不编写一个脚本，首先用 Perl（没有增益），然后用 C++（增益快 35 倍）。

于 2014-12-16T22:48:47.567 回答