# No unique index on site\_settings name column
**URL:** https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047
**Category:** Development
**Created:** [3월 19, 2019, 2:03오후 UTC](https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047 "2019-03-19T14:03:47Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@LeoMcA](https://meta.discourse.org/u/LeoMcA)
#### Post date: [3월 19, 2019, 2:03오후 UTC](https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047/1 "2019-03-19T14:03:48Z")
When updating today, [this migration](https://github.com/discourse/discourse/blob/3fd04df781f1cb736228e3212ef79ab2ee20326e/db/migrate/20190227210035_add_missing_topic_id_site_settings.rb) failed:
```
PG::CardinalityViolation: ERROR: more than one row returned by a subquery used as an expression
: INSERT INTO site_settings(name, data_type, value, created_at, updated_at)
SELECT 'lounge_welcome_topic_id', 3, id, created_at, updated_at
FROM topics
WHERE title = 'Welcome to the Lounge' AND NOT EXISTS(
SELECT 1
FROM site_settings
WHERE name = 'lounge_welcome_topic_id'
) AND category_id = (
SELECT value::INT
FROM site_settings
WHERE name = 'lounge_category_id'
)
ORDER BY created_at
LIMIT 1
```
So I run the two subqueries, and… 🤨
```
SELECT *
FROM site_settings
WHERE name = 'lounge_category_id';
id | name | data_type | value | created_at | updated_at
----+--------------------+-----------+-------+----------------------------+----------------------------
60 | lounge_category_id | 3 | 14 | 2014-02-17 23:45:49.295261 | 2014-02-17 23:45:49.295261
2 | lounge_category_id | 3 | 2 | 2014-02-17 23:45:39.227589 | 2014-02-18 02:31:03.144083
(2 rows)
```
That second row points to the actual lounge category (`id=2`), there’s no category with `id=14`.
I have no idea how we got duplicate `lounge_category_id` settings way back in 2014, and if this is the result of a _really_ legacy bug, or something weird that happened on our instance back then.
This is the only duplicated site setting I can see, but it highlights there’s no unique index on the `name` column, which I imagine there should be.
I’ve deleted the wrong row, and the migration ran fine.
---
### Author:  [@codinghorror](https://meta.discourse.org/u/codinghorror)
#### Post date: [3월 20, 2019, 2:48오전 UTC](https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047/2 "2019-03-20T02:48:36Z")
I think this might be relevant to @gerhard
---
### Author:  [@sam](https://meta.discourse.org/u/sam)
#### Post date: [3월 20, 2019, 4:27오전 UTC](https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047/3 "2019-03-20T04:27:58Z")
Definitely relevant to @gerhard but strongly agree we should have a unique index on name on the `site_settings` table (and throw away non unique rows in the migration)
We will make that happen.
---
### Author:  [@gerhard](https://meta.discourse.org/u/gerhard)
#### Post date: [3월 25, 2019, 4:33오후 UTC](https://meta.discourse.org/t/no-unique-index-on-site-settings-name-column/112047/5 "2019-03-25T16:33:02Z")
Done in [FIX: Make migration resilient against duplicate site settings · discourse/discourse@467c17d · GitHub](https://github.com/discourse/discourse/commit/467c17da53a9fe3c1f83c8c0321fd822ca5833fd) and [FIX: Remove duplicate site settings and add unique index · discourse/discourse@cb70a32 · GitHub](https://github.com/discourse/discourse/commit/cb70a328f51a25cd278df8f71d88f45df007740a)