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Update Migration Style Guide

This commit is contained in:
Valery Sizov 2019-08-06 17:08:28 +03:00
parent 4aa824e705
commit 19f36a3452
1 changed files with 3 additions and 8 deletions
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11
doc/development/migration_style_guide.md
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@ -10,9 +10,7 @@ migrations are written carefully, can be applied online and adhere to the style
guide below.
Migrations are **not** allowed to require GitLab installations to be taken
offline unless _absolutely necessary_. Downtime assumptions should be based on
the behaviour of a migration when performed using PostgreSQL, as various
operations in MySQL may require downtime without there being alternatives.
offline unless _absolutely necessary_.
When downtime is necessary the migration has to be approved by:
@ -343,10 +341,7 @@ class AddOptionsToBuildMetadata < ActiveRecord::Migration[5.0]
end
```
On MySQL the `JSON` and `JSONB` is translated to `TEXT 1MB`, as `JSONB` is PostgreSQL only feature.
For above reason you have to use a serializer to provide a translation layer
in order to support PostgreSQL and MySQL seamlessly:
You have to use a serializer to provide a translation layer:
```ruby
class BuildMetadata
@ -356,7 +351,7 @@ end
## Testing
Make sure that your migration works with MySQL and PostgreSQL with data. An
Make sure that your migration works for databases with data. An
empty database does not guarantee that your migration is correct.
Make sure your migration can be reversed.