diff --git a/netx_api/main.py b/netx_api/main.py
index 6e8a236..ea2e95e 100644
--- a/netx_api/main.py
+++ b/netx_api/main.py
@@ -550,6 +550,23 @@ def on_startup() -> None:
             conn.exec_driver_sql("ALTER TABLE ume_inventory_ne ADD COLUMN IF NOT EXISTS net_mask VARCHAR(128) DEFAULT ''")
             conn.exec_driver_sql("ALTER TABLE ume_inventory_ne ADD COLUMN IF NOT EXISTS create_time VARCHAR(64) DEFAULT ''")
             conn.exec_driver_sql("ALTER TABLE ume_inventory_ne ADD COLUMN IF NOT EXISTS creator VARCHAR(128) DEFAULT ''")
+            # Allow long UME alarm fields; avoid StringDataRightTruncation on large payloads.
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN alarm_key TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN object_name TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN event_type TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN native_probable_cause TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN perceived_severity TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN is_cleared TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN time_created TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_current ALTER COLUMN root_cause_alarm_indication TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN alarm_key TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN object_name TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN event_type TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN native_probable_cause TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN perceived_severity TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN is_cleared TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN time_created TYPE TEXT")
+            conn.exec_driver_sql("ALTER TABLE ume_alarms_history ALTER COLUMN root_cause_alarm_indication TYPE TEXT")
             # Simplify alarm tables: display fields come from runtime join with inventory table.
             conn.exec_driver_sql("ALTER TABLE ume_alarms_current DROP COLUMN IF EXISTS ne_name")
             conn.exec_driver_sql("ALTER TABLE ume_alarms_current DROP COLUMN IF EXISTS user_label")
diff --git a/netx_api/models.py b/netx_api/models.py
index 64f858b..70a0d69 100644
--- a/netx_api/models.py
+++ b/netx_api/models.py
@@ -166,15 +166,15 @@ class UmeInventoryNE(Base):
 class UmeAlarmCurrent(Base):
     __tablename__ = "ume_alarms_current"
 
-    alarm_key: Mapped[str] = mapped_column(String(256), primary_key=True)
+    alarm_key: Mapped[str] = mapped_column(Text, primary_key=True)
     ne_id: Mapped[str] = mapped_column(String(128), default="", index=True)
-    object_name: Mapped[str] = mapped_column(String(512), default="", index=True)
-    event_type: Mapped[str] = mapped_column(String(128), default="")
-    native_probable_cause: Mapped[str] = mapped_column(String(256), default="")
-    perceived_severity: Mapped[str] = mapped_column(String(64), default="", index=True)
-    is_cleared: Mapped[str] = mapped_column(String(16), default="", index=True)
-    time_created: Mapped[str] = mapped_column(String(64), default="", index=True)
-    root_cause_alarm_indication: Mapped[str] = mapped_column(String(32), default="")
+    object_name: Mapped[str] = mapped_column(Text, default="", index=True)
+    event_type: Mapped[str] = mapped_column(Text, default="")
+    native_probable_cause: Mapped[str] = mapped_column(Text, default="")
+    perceived_severity: Mapped[str] = mapped_column(Text, default="", index=True)
+    is_cleared: Mapped[str] = mapped_column(Text, default="", index=True)
+    time_created: Mapped[str] = mapped_column(Text, default="", index=True)
+    root_cause_alarm_indication: Mapped[str] = mapped_column(Text, default="")
     first_seen_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
     last_seen_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, index=True)
     raw_json: Mapped[str] = mapped_column(Text, default="{}")
@@ -183,15 +183,15 @@ class UmeAlarmCurrent(Base):
 class UmeAlarmHistory(Base):
     __tablename__ = "ume_alarms_history"
 
-    alarm_key: Mapped[str] = mapped_column(String(256), primary_key=True)
+    alarm_key: Mapped[str] = mapped_column(Text, primary_key=True)
     ne_id: Mapped[str] = mapped_column(String(128), default="", index=True)
-    object_name: Mapped[str] = mapped_column(String(512), default="", index=True)
-    event_type: Mapped[str] = mapped_column(String(128), default="")
-    native_probable_cause: Mapped[str] = mapped_column(String(256), default="")
-    perceived_severity: Mapped[str] = mapped_column(String(64), default="", index=True)
-    is_cleared: Mapped[str] = mapped_column(String(16), default="", index=True)
-    time_created: Mapped[str] = mapped_column(String(64), default="", index=True)
-    root_cause_alarm_indication: Mapped[str] = mapped_column(String(32), default="")
+    object_name: Mapped[str] = mapped_column(Text, default="", index=True)
+    event_type: Mapped[str] = mapped_column(Text, default="")
+    native_probable_cause: Mapped[str] = mapped_column(Text, default="")
+    perceived_severity: Mapped[str] = mapped_column(Text, default="", index=True)
+    is_cleared: Mapped[str] = mapped_column(Text, default="", index=True)
+    time_created: Mapped[str] = mapped_column(Text, default="", index=True)
+    root_cause_alarm_indication: Mapped[str] = mapped_column(Text, default="")
     first_seen_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
     last_seen_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, index=True)
     raw_json: Mapped[str] = mapped_column(Text, default="{}")
diff --git a/netx_api/ume_sync_service.py b/netx_api/ume_sync_service.py
index db4d184..dbded27 100644
--- a/netx_api/ume_sync_service.py
+++ b/netx_api/ume_sync_service.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import json
 import logging
+import hashlib
 from datetime import datetime, timezone
 from typing import Any
 
@@ -43,6 +44,9 @@ def _pick(d: dict[str, Any], *keys: str) -> Any:
 def _alarm_key(alarm: dict[str, Any]) -> str:
     key = _s(_pick(alarm, "alarmKey", "alarm-key","alarmkey","id"))
     if key:
+        # Keep full upstream key; use a stable digest only for pathological ultra-long keys.
+        if len(key) > 512:
+            return "sha256:" + hashlib.sha256(key.encode("utf-8", errors="ignore")).hexdigest()
         return key
     parts = [
         _s(_pick(alarm, "objectName", "object-name")),
@@ -51,7 +55,10 @@ def _alarm_key(alarm: dict[str, Any]) -> str:
         _s(_pick(alarm, "nativeProbableCause", "native-probable-cause")),
     ]
     merged = "|".join(x for x in parts if x)
-    return merged or f"fallback-{datetime.utcnow().timestamp()}"
+    raw = merged or f"fallback-{datetime.utcnow().timestamp()}"
+    if len(raw) > 512:
+        return "sha256:" + hashlib.sha256(raw.encode("utf-8", errors="ignore")).hexdigest()
+    return raw
 
 
 def _derive_ne_id_from_alarm(alarm: dict[str, Any]) -> str:
@@ -338,7 +345,7 @@ def _sync_alarms_common(
                     inserted += 1
                 else:
                     updated += 1
-            existing.ne_id = _derive_ne_id_from_alarm(alarm)
+            existing.ne_id = _s(_derive_ne_id_from_alarm(alarm))
             existing.object_name = _s(_pick(alarm, "objectName", "object-name"))
             existing.event_type = _s(_pick(alarm, "eventType", "event-type"))
             existing.native_probable_cause = _s(_pick(alarm, "nativeProbableCause", "native-probable-cause"))