ea41405209
The following query
```sql
SELECT spree_orders . *
FROM spree_orders
WHERE spree_orders . user_id = ?
AND spree_orders . completed_at IS ?
AND spree_orders . created_by_id = ?
ORDER BY created_at DESC LIMIT ?
```
performs quite badly even though LIMIT is always 1 because:
* ORDER BY requires sorting by a column which is not indexed therefore
a sequential scan is performed.
* Although `completed_at` is indexed, `user_id` and `created_by_id` are
not causing a sequential scan.
To make it worse this query is executed very often in the following
controllers among others also related to checkout:
* CartController#populate
* EnterprisesController#Shop
* LineItemsController#bought
* ShopController#products
* ShopController#order_cycle
In some cases this query alone accounts for 66.8% of the total time
of the endpoint.
Results
See by yourself. We move from 56.643ms to 0.077ms. Pretty neat.
```
openfoodnetwork=> explain analyze SELECT "spree_orders".* FROM "spree_orders" WHERE "spree_orders"."user_id" = 1 AND "spree_orders"."completed_at" IS NULL AND "spree_orders"."created_by_id" = 1 ORDER BY created_at DESC LIMIT 1;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------
Limit (cost=11753.03..11753.04 rows=1 width=195) (actual time=56.580..56.580 rows=0 loops=1)
-> Sort (cost=11753.03..11753.04 rows=1 width=195) (actual time=56.578..56.578 rows=0 loops=1)
Sort Key: created_at DESC
Sort Method: quicksort Memory: 25kB
-> Seq Scan on spree_orders (cost=0.00..11753.02 rows=1 width=195) (actual time=56.571..56.571 rows=0 loops=1)
Filter: ((completed_at IS NULL) AND (user_id = 1) AND (created_by_id = 1))
Rows Removed by Filter: 256135
Planning time: 0.252 ms
Execution time: 56.643 ms
(9 rows)
openfoodnetwork=> CREATE INDEX ON spree_orders (completed_at, user_id, created_by_id, created_at);
CREATE INDEX
openfoodnetwork=> explain analyze SELECT "spree_orders".* FROM "spree_orders" WHERE "spree_orders"."user_id" = 1 AND "spree_orders"."completed_at" IS NULL AND "spree_orders"."created_by_id" = 1 ORDER BY created_at DESC LIMIT 1;
mit (cost=8.45..8.46 rows=1 width=195) (actual time=0.030..0.030 rows=0 loops=1)
-> Sort (cost=8.45..8.46 rows=1 width=195) (actual time=0.029..0.029 rows=0 loops=1)
Sort Key: created_at DESC
Sort Method: quicksort Memory: 25kB
-> Index Scan using spree_orders_completed_at_user_id_created_by_id_created_at_idx on spree_orders (cost=0.42..8.44 rows=1 width=195) (actual time=0.021..0.021 rows=0 loops=1)
Index Cond: ((completed_at IS NULL) AND (user_id = 1) AND (created_by_id = 1))
Planning time: 0.199 ms
Execution time: 0.077 ms
```
Open Food Network
The Open Food Network is an online marketplace for local food. It enables a network of independent online food stores that connect farmers and food hubs (including coops, online farmers' markets, independent food businesses etc); with individuals and local businesses. It gives farmers and food hubs an easier and fairer way to distribute their food.
Supported by the Open Food Foundation and a network of global affiliates, we are proudly open source and not-for-profit - we're trying to seriously disrupt the concentration of power in global agri-food systems, and we need as many smart people working together on this as possible.
We're part of global movement - get involved!
- Join the conversation on Slack. Make sure you introduce yourself in the #general channel
- Head to https://openfoodnetwork.org for more information about the global OFN project.
- Check out the User Guide for a list of features and tutorials.
- Join our discussion forum.
Contributing
If you are interested in contributing to the OFN in any capacity, please introducing yourself on Slack, and have a look through our Contributor Guide
Our GETTING_STARTED and CONTRIBUTING guides are the best place to start for developers looking to set up a development environment and make contributions to the codebase.
Provisioning
If you're interested in provisioning a server, see ofn-install for the project's Ansible playbooks.
We also have a Super Admin Guide to help with configuration of new servers.
Testing
We use BrowserStack as a manual testing tool. BrowserStack provides open source projects with unlimited and free of charge accounts. A big thanks to them!
Licence
Copyright (c) 2012 - 2019 Open Food Foundation, released under the AGPL licence.