# What this PR does
Related to https://github.com/grafana/oncall-private/issues/2947
**NOTE**
This PR introduces steps 1 and 2 of the 3 part migration proposed
[here](https://raintank-corp.slack.com/archives/C06K1MQ07GS/p1732555465144099).
Step 3, swapping reads to be from the new-column and dropping
dual-writes, will be done in a future PR/release.
---
I’m tackling this work now because _ultimately_ I want to move
`AlertReceiveChannel.rate_limited_in_slack_at` to
`SlackChannel.rate_limited_at` , but first I sorta need to refactor
`SlackMessage.channel_id` from a `CHAR` field to a foreign key
relationship (because in the spots where we touch Slack rate limiting,
like
[here](https://github.com/grafana/oncall/blob/dev/engine/apps/slack/alert_group_slack_service.py#L42-L50)
for example, we only have `slack_message.channel_id`, which means I need
to do extra queries to fetch the appropriate `SlackChannel` to then be
able to get/set `SlackChannel.rate_limited_at`
Other minor stuffs:
- it also prepares us to drop `SlackMessage._slack_team_identity`. We
already have a `@property` of `SlackMessage.slack_team_identity` (which
[previously had some hacky
logic](https://github.com/grafana/oncall/blob/dev/engine/apps/slack/models/slack_message.py#L74-L84)).
I've refactored `SlackMessage.slack_team_identity` to simply point to
`self.organization.slack_team_identity` + updated our code to _stop_
setting `SlackMessage._slack_team_identity` (will drop this column in
future release)
## Checklist
- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
show up in the autogenerated release notes.
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