Most of the way to getting my first test passing.

packages/server/src/api/routes/tests/table.spec.ts

@@ -456,9 +456,11 @@ describe("/tables", () => {
 
       const migratedTable = await config.api.table.get(table._id!)
       expect(migratedTable.schema["user column"]).toBeDefined()
+      expect(migratedTable.schema["user relationship"]).not.toBeDefined()
 
       const rows = await config.api.row.fetch(table._id!)
       expect(rows[0]["user column"]).toBeDefined()
+      expect(rows[0]["user relationship"]).not.toBeDefined()
     })
   })
 })

packages/server/src/sdk/app/tables/index.ts

@@ -16,6 +16,8 @@ import datasources from "../datasources"
 import { populateExternalTableSchemas } from "./validation"
 import sdk from "../../../sdk"
 import { migrate } from "./migration"
+import { DocumentInsertResponse } from "@budibase/nano"
+import { cloneDeep } from "lodash"
 
 async function getAllInternalTables(db?: Database): Promise<Table[]> {
   if (!db) {
@@ -75,23 +77,28 @@ function enrichViewSchemas(table: Table): TableResponse {
   }
 }
 
-async function saveTable(table: Table) {
+async function saveTable(table: Table): Promise<Table> {
   const db = context.getAppDB()
+  let resp: DocumentInsertResponse
   if (isExternalTable(table._id!)) {
     const datasource = await sdk.datasources.get(table.sourceId!)
     datasource.entities![table.name] = table
-    await db.put(datasource)
+    resp = await db.put(datasource)
   } else {
-    await db.put(table)
+    resp = await db.put(table)
   }
+
+  let tableClone = cloneDeep(table)
+  tableClone._rev = resp.rev
+  return tableClone
 }
 
-async function addColumn(table: Table, newColumn: FieldSchema) {
+async function addColumn(table: Table, newColumn: FieldSchema): Promise<Table> {
   if (newColumn.name in table.schema) {
     throw `Column "${newColumn.name}" already exists on table "${table.name}"`
   }
   table.schema[newColumn.name] = newColumn
-  await saveTable(table)
+  return await saveTable(table)
 }
 
 export default {

packages/server/src/sdk/app/tables/migration.ts

@@ -1,15 +1,19 @@
-import { BadRequestError } from "@budibase/backend-core"
+import { BadRequestError, context } from "@budibase/backend-core"
 import {
   BBReferenceFieldMetadata,
   FieldSchema,
   InternalTable,
   RelationshipFieldMetadata,
+  Row,
   Table,
   isBBReferenceField,
   isRelationshipField,
 } from "@budibase/types"
 import sdk from "../../../sdk"
 import { isExternalTable } from "../../../../src/integrations/utils"
+import { db as dbCore } from "@budibase/backend-core"
+import { EventType, updateLinks } from "../../../../src/db/linkedRows"
+import { cloneDeep } from "lodash"
 
 export async function migrate(
   table: Table,
@@ -17,10 +21,15 @@ export async function migrate(
   newColumn: FieldSchema
 ) {
   let migrator = getColumnMigrator(table, oldColumn, newColumn)
+  let oldTable = cloneDeep(table)
 
-  await sdk.tables.addColumn(table, newColumn)
+  table = await sdk.tables.addColumn(table, newColumn)
 
-  migrator.doMigration()
+  await migrator.doMigration()
+
+  delete table.schema[oldColumn.name]
+  await sdk.tables.saveTable(table)
+  await updateLinks({ eventType: EventType.TABLE_UPDATED, table, oldTable })
 }
 
 interface ColumnMigrator {
@@ -80,6 +89,29 @@ class UserColumnMigrator implements ColumnMigrator {
 
   async doMigration() {
     let rows = await sdk.rows.fetch(this.table._id!)
+    let rowsById = rows.reduce((acc, row) => {
+      acc[row._id!] = row
+      return acc
+    }, {} as Record<string, Row>)
+
     let links = await sdk.links.fetchWithDocument(this.table._id!)
+    for (let link of links) {
+      if (link.doc1.tableId !== this.table._id) {
+        continue
+      }
+      if (link.doc1.fieldName !== this.oldColumn.name) {
+        continue
+      }
+      if (link.doc2.tableId !== InternalTable.USER_METADATA) {
+        continue
+      }
+
+      let userId = dbCore.getGlobalIDFromUserMetadataID(link.doc2.rowId)
+      let row = rowsById[link.doc1.rowId]
+      row[this.newColumn.name] = userId
+    }
+
+    let db = context.getAppDB()
+    await db.bulkDocs(rows)
   }
 }