fix: handle first observed migration change (#974)

functions/pre_alter_columns.sql

@@ -3,7 +3,7 @@ BEGIN
     -- Check if the column "count" exists in the "config_changes" table
     IF EXISTS (
         SELECT 1
-        FROM information_schema.columns 
+        FROM information_schema.columns
         WHERE table_schema = 'public'
         AND table_name = 'config_changes'
         AND column_name = 'count'
@@ -15,12 +15,29 @@ BEGIN
     END IF;
 END $$;
 
+DO $$
+BEGIN
+    -- Check if the column "first_observed" exists in the "config_changes" table
+    IF EXISTS (
+        SELECT 1
+        FROM information_schema.columns
+        WHERE table_schema = 'public'
+        AND table_name = 'config_changes'
+        AND column_name = 'first_observed'
+    ) THEN
+        -- Update existing NULL values in the "first_observed" column
+        UPDATE config_changes
+        SET first_observed = NOW()
+        WHERE first_observed IS NULL;
+    END IF;
+END $$;
+
 DO $$
 BEGIN
     -- Check if the column "category" exists in the "playbooks" table
     IF EXISTS (
         SELECT 1
-        FROM information_schema.columns 
+        FROM information_schema.columns
         WHERE table_schema = 'public'
         AND table_name = 'playbooks'
         AND column_name = 'category'