## Summary
We want to persist information about a given user relating to the case and the signals in the `cusi_user` table, so that changes to this information elsewhere do not lead to a change in Suggested Investigations unless intended
## Background
- We need a way to store information relating to each user in a #checkuser-suggestedinvestigations case
-- This information may be different for each user
-- This information will have fixed allowable values
- We can represent this data using an integer field which we treat as a BIT field, using each bit as a bit flag which is parsed in PHP
-- This means that we can store information about the user efficiently as long as the information is representable using fixed values
--- For our use cases, we only for now need to store information about a state as opposed to the raw value
--- We don't expect the need to store raw data for other use cases, and a bit field should be acceptable for other use cases
- See T411118 (private task) for more detail on the need for this column
## Proposed schema change
Addition of a `siu_info` field to `cusi_user`. This field will not need to be indexed or added to the primary key. On WMF wikis this table is on the `extension1` cluster
```
describe cusi_user;
+-------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+-------+
| siu_user_id | int(10) unsigned | NO | PRI | NULL | |
| siu_sic_id | int(10) unsigned | NO | PRI | NULL | |
| siu_info | int(10) unsigned | NO | | 0 | |
+-------------+------------------+------+-----+---------+-------+
```
## Acceptance criteria
- [ ] An unsigned integer field is added to `cusi_user` which is treated as field storing bit flags
- [ ] A #schema-change-in-production ticket is filed to apply this change to all wikis in `checkuser-suggested-investigations.dblist`