Commit 74dd74a2 authored by Mike Jang's avatar Mike Jang

Merge branch 'doc-multi-version-compatibility' into 'master'

Add example to the multi-version-compatibility

See merge request gitlab-org/gitlab!37031
parents d2dca1ec 65793e64
......@@ -60,3 +60,18 @@ We added a `NOT NULL` constraint to a column and marked it as a `NOT VALID` cons
But even with that, this was still a problem because the old servers were still inserting new rows with null values.
For more information, see [the relevant issue](https://gitlab.com/gitlab-com/gl-infra/production/-/issues/1944).
### Downtime on release features between canary and production deployment
To address the issue, we added a new column to an existing table with a `NOT NULL` constraint without
specifying a default value. In other words, this requires the application to set a value to the column.
The older version of the application didn't set the `NOT NULL` constraint since the entity/concept didn't
exist before.
The problem starts right after the canary deployment is complete. At that moment,
the database migration (to add the column) has successfully run and canary instance starts using
the new application code, hence QA was successful. Unfortunately, the production
instance still uses the older code, so it started failing to insert a new release entry.
For more information, see [this issue related to the Releases API](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/64151).
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