diff --git a/packages/backend/server/src/core/doc/manager.ts b/packages/backend/server/src/core/doc/manager.ts
index f8c23407db..6a3836cb37 100644
--- a/packages/backend/server/src/core/doc/manager.ts
+++ b/packages/backend/server/src/core/doc/manager.ts
@@ -19,6 +19,7 @@ import {
 
 import {
   Cache,
+  CallTimer,
   Config,
   EventEmitter,
   type EventPayload,
@@ -463,6 +464,7 @@ export class DocManager implements OnModuleInit, OnModuleDestroy {
     });
   }
 
+  @CallTimer('doc', 'upsert')
   private async upsert(
     workspaceId: string,
     guid: string,
@@ -472,73 +474,87 @@ export class DocManager implements OnModuleInit, OnModuleDestroy {
     updatedAt: Date,
     initialSeq?: number
   ) {
-    return this.lockSnapshotForUpsert(workspaceId, guid, async () => {
-      const blob = Buffer.from(encodeStateAsUpdate(doc));
+    const blob = Buffer.from(encodeStateAsUpdate(doc));
 
-      if (isEmptyBuffer(blob)) {
-        return false;
+    if (isEmptyBuffer(blob)) {
+      return false;
+    }
+
+    const state = Buffer.from(encodeStateVector(doc));
+
+    await this.db.$queryRaw`BEGIN;`;
+    let committed = false;
+    const commit = async () => {
+      if (!committed) {
+        committed = true;
+        await this.db.$queryRaw`COMMIT;`;
       }
+    };
+    try {
+      const [snapshot]: {
+        workspace_id: string;
+        id: string;
+        blob: Buffer;
+        state?: Buffer;
+      }[] = await this.db.$queryRaw`
+        -- LOCK TABLE "Snapshot" IN SHARE ROW EXCLUSIVE MODE;
+        SELECT * FROM snapshots WHERE workspace_id = ${workspaceId} AND guid = ${guid} limit 1
+        FOR UPDATE;
+      `;
 
-      const state = Buffer.from(encodeStateVector(doc));
-
-      return await this.db.$transaction(async db => {
-        const snapshot = await db.snapshot.findUnique({
-          where: {
-            id_workspaceId: {
-              id: guid,
-              workspaceId,
-            },
-          },
-        });
-
-        // update
-        if (snapshot) {
-          // only update if state is newer
-          if (isStateNewer(snapshot.state ?? Buffer.from([0]), state)) {
-            await db.snapshot.update({
-              select: {
-                seq: true,
-              },
-              where: {
-                id_workspaceId: {
-                  workspaceId,
-                  id: guid,
-                },
-              },
-              data: {
-                blob,
-                state,
-                updatedAt,
-              },
-            });
-
-            return true;
-          } else {
-            return false;
-          }
-        } else {
-          // create
-          await db.snapshot.create({
+      // update
+      if (snapshot) {
+        // only update if state is newer
+        if (isStateNewer(snapshot.state ?? Buffer.from([0]), state)) {
+          await this.db.snapshot.update({
             select: {
               seq: true,
             },
+            where: {
+              id_workspaceId: {
+                workspaceId,
+                id: guid,
+              },
+            },
             data: {
-              id: guid,
-              workspaceId,
               blob,
               state,
-              seq: initialSeq,
-              createdAt: updatedAt,
               updatedAt,
             },
           });
 
           return true;
+        } else {
+          return false;
         }
-      });
-    });
-  }
+      } else {
+        // create
+        // no record exists, should commit the previous row lock first
+        await commit();
+        await this.db.snapshot.create({
+          select: {
+            seq: true,
+          },
+          data: {
+            id: guid,
+            workspaceId,
+            blob,
+            state,
+            seq: initialSeq,
+            createdAt: updatedAt,
+            updatedAt,
+          },
+        });
 
+        return true;
+      }
+    } catch (e) {
+      await this.db.$queryRaw`ROLLBACK;`;
+      throw e;
+    } finally {
+      await commit();
+    }
+  }
   private async _get(
     workspaceId: string,
     guid: string
@@ -559,6 +575,7 @@ export class DocManager implements OnModuleInit, OnModuleDestroy {
    * Squash updates into a single update and save it as snapshot,
    * and delete the updates records at the same time.
    */
+  @CallTimer('doc', 'squash')
   private async squash(updates: Update[], snapshot: Snapshot | null) {
     if (!updates.length) {
       throw new Error('No updates to squash');
@@ -761,18 +778,6 @@ export class DocManager implements OnModuleInit, OnModuleDestroy {
     );
   }
 
-  async lockSnapshotForUpsert<T>(
-    workspaceId: string,
-    guid: string,
-    job: () => Promise<T>
-  ) {
-    return this.doWithLock(
-      'doc:manager:snapshot',
-      `${workspaceId}::${guid}`,
-      job
-    );
-  }
-
   @Cron(CronExpression.EVERY_MINUTE)
   async reportUpdatesQueueCount() {
     metrics.doc