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Diffstat (limited to 'doc/development/migration_style_guide.md')
| -rw-r--r-- | doc/development/migration_style_guide.md | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/doc/development/migration_style_guide.md b/doc/development/migration_style_guide.md index 40457dbb533..e1444f1a726 100644 --- a/doc/development/migration_style_guide.md +++ b/doc/development/migration_style_guide.md @@ -33,7 +33,7 @@ compatible. For GitLab.com, please take into consideration that regular migrations (under `db/migrate`) are run before [Canary is deployed](https://gitlab.com/gitlab-com/gl-infra/readiness/-/tree/master/library/canary/#configuration-and-deployment), -and post-deployment migrations (`db/post_migrate`) are run after the deployment to production has finished. +and [post-deployment migrations](post_deployment_migrations.md) (`db/post_migrate`) are run after the deployment to production has finished. ## Schema Changes @@ -114,6 +114,30 @@ rails schema statement: [`add_index`](https://api.rubyonrails.org/v5.2/classes/A This is a blocking operation, but it doesn't cause problems because the table is not yet used, and therefore it does not have any records yet. +## Naming conventions + +We keep column names consistent with [ActiveRecord's schema conventions](https://guides.rubyonrails.org/active_record_basics.html#schema-conventions). + +Custom index names should follow the pattern `index_#{table_name}_on_#{column_1}_and_#{column_2}_#{condition}`. + +Examples: + +- `index_services_on_type_and_id_and_template_when_active` +- `index_projects_on_id_service_desk_enabled` +- `index_clusters_on_enabled_cluster_type_id_and_created_at` + +### Truncate long index names + +PostgreSQL [limits the length of identifiers](https://www.postgresql.org/docs/current/limits.html), +like column or index names. Column names are not usually a problem, but index names tend +to be longer. Some methods for shortening a name that's too long: + +- Prefix it with `i_` instead of `index_`. +- Skip redundant prefixes. For example, + `index_vulnerability_findings_remediations_on_vulnerability_remediation_id` becomes + `index_vulnerability_findings_remediations_on_remediation_id`. +- Instead of columns, specify the purpose of the index, such as `index_users_for_unconfirmation_notification`. + ## Heavy operations in a single transaction When using a single-transaction migration, a transaction holds a database connection |