diff --git a/config/default.json b/config/default.json
index 14b276c..7f33d12 100644
--- a/config/default.json
+++ b/config/default.json
@@ -28,7 +28,12 @@
     }
   },
   "sync": {
-    "layers": ["obstacles"],
+    "layers": [
+      {
+        "name": "obstacles",
+        "query": "query { obstacles { createdBy creationTime deleted entityVersion geography { coordinates { latitude longitude } graphicsObjectKind { value } height obstacleHeightsRange { displayName } } id identifiers { essence { displayName value } name number } lastUpdateTime lastUpdatedBy } }"
+      }
+    ],
     "syncIntervalMs": 500,
     "pollIntervalMs": 600000,
     "pageSize": 1000,
diff --git a/src/containerConfig.ts b/src/containerConfig.ts
index c50f22f..482c447 100644
--- a/src/containerConfig.ts
+++ b/src/containerConfig.ts
@@ -29,9 +29,10 @@ export const registerExternalValues = async (options?: RegisterOptions): Promise
   configInstance.initializeMetrics(metricsRegistry);
 
   const syncConfig = getSyncConfig();
-  const dataSource = await initializeDb(syncConfig.layers);
+  const layers = syncConfig.layers.map((l) => l.name);
+  const dataSource = await initializeDb(layers);
   const { host, port, database } = dataSource.options as { host: string; port: number; database: string };
-  logger.info(`Database connected to ${host}:${port}/${database} (layer partitions: ${syncConfig.layers.join(', ')})`);
+  logger.info(`Database connected to ${host}:${port}/${database} (layer partitions: ${layers.join(', ')})`);
 
   const syncManager = new SyncManager(logger);
 
diff --git a/src/dal/repositories/layerDataRepository.ts b/src/dal/repositories/layerDataRepository.ts
index ab921e6..46ca515 100644
--- a/src/dal/repositories/layerDataRepository.ts
+++ b/src/dal/repositories/layerDataRepository.ts
@@ -19,7 +19,7 @@ async function insertRow(layerName: string, object: LayerObject): Promise<void>
     .insert()
     .into(LayerObjectEntity)
     .values({ layerName, id: object.id, geom: object.geom, properties: object.properties } as unknown as ObjectLiteral)
-    .orIgnore()
+    .orUpdate(['geom', 'properties'], ['layer_name', 'id'])
     .execute();
 }
 
@@ -41,7 +41,7 @@ export async function insertObjects(logger: Logger, layerName: string, objects:
           .insert()
           .into(LayerObjectEntity)
           .values(rows as unknown as ObjectLiteral[])
-          .orIgnore()
+          .orUpdate(['geom', 'properties'], ['layer_name', 'id'])
           .execute();
       } catch (batchErr) {
         logger.warn({ msg: 'Batch insert failed, falling back to per-object inserts', layerName, count: objects.length, err: batchErr });
diff --git a/src/externalClients/layersClient/layersClient.ts b/src/externalClients/layersClient/layersClient.ts
index 242127c..d7f97ea 100644
--- a/src/externalClients/layersClient/layersClient.ts
+++ b/src/externalClients/layersClient/layersClient.ts
@@ -64,7 +64,7 @@ export async function fetchPage(logger: Logger, layerName: string, sequence: str
     async () => {
       const response = await axios.post<GraphQLResponse>(
         config.thirdPartyBaseUrl,
-        { query: buildLayerQuery(layerName) },
+        { query: buildLayerQuery(layerName, config.layers) },
         {
           headers: {
             'Content-Type': 'application/json',
diff --git a/src/externalClients/layersClientModel.ts b/src/externalClients/layersClientModel.ts
index cc30505..44288ff 100644
--- a/src/externalClients/layersClientModel.ts
+++ b/src/externalClients/layersClientModel.ts
@@ -1,36 +1,12 @@
-// Third-party API uses the layer name as the root query field.
-// Pagination/auth inputs are passed via HTTP headers, not GraphQL variables.
-export function buildLayerQuery(layerName: string): string {
-  return `query {
-  ${layerName} {
-    createdBy
-    creationTime
-    deleted
-    entityVersion
-    geography {
-      coordinates {
-        latitude
-        longitude
-      }
-      graphicsObjectKind {
-        value
-      }
-      height
-      obstacleHeightsRange {
-        displayName
-      }
-    }
-    id
-    identifiers {
-      essence {
-        displayName
-        value
-      }
-      name
-      number
-    }
-    lastUpdateTime
-    lastUpdatedBy
+import type { LayerConfig } from '../types';
+
+// The query per layer comes from config (sync.layers), matched by layer name.
+// The layer name is the root GraphQL query field. A layer with no configured
+// query is treated as a misconfiguration and skipped (error thrown).
+export function buildLayerQuery(layerName: string, layers: LayerConfig[]): string {
+  const layer = layers.find((l) => l.name === layerName);
+  if (layer === undefined || layer.query.trim() === '') {
+    throw new Error(`No query configured for layer "${layerName}"`);
   }
-}`;
+  return layer.query;
 }
diff --git a/src/scheduler/syncManager.ts b/src/scheduler/syncManager.ts
index 3382efd..59fba0f 100644
--- a/src/scheduler/syncManager.ts
+++ b/src/scheduler/syncManager.ts
@@ -23,9 +23,10 @@ export class SyncManager {
   public async start(): Promise<void> {
     const config = getSyncConfig();
 
-    this.logger.info(`Initializing sync for layers: ${config.layers.join(', ')}`);
+    const layers = config.layers.map((l) => l.name);
+    this.logger.info(`Initializing sync for layers: ${layers.join(', ')}`);
 
-    await this.initialize(config.layers);
+    await this.initialize(layers);
 
     this.running = true;
     this.loopPromise = this.runSchedulerLoop();
diff --git a/src/types/index.ts b/src/types/index.ts
index dffea1d..73b4c2a 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -2,4 +2,5 @@ export { SyncStatus, SyncStateEntry } from './syncState';
 export type { ScheduleEntry } from './scheduler';
 export type { LayerObject, ThirdPartyResponse } from './thirdParty';
 export type { SyncConfig } from './syncConfig';
+export type { LayerConfig } from './layerConfig';
 export type { DbConfig } from './dbConfig';
diff --git a/src/types/layerConfig.ts b/src/types/layerConfig.ts
new file mode 100644
index 0000000..f9bfa21
--- /dev/null
+++ b/src/types/layerConfig.ts
@@ -0,0 +1,4 @@
+export interface LayerConfig {
+  name: string;
+  query: string;
+}
diff --git a/src/types/syncConfig.ts b/src/types/syncConfig.ts
index b168b2e..e89933b 100644
--- a/src/types/syncConfig.ts
+++ b/src/types/syncConfig.ts
@@ -1,5 +1,8 @@
+import type { LayerConfig } from './layerConfig';
+
 export interface SyncConfig {
-  layers: string[];
+  // Layers to sync; each entry pairs a layer name with its GraphQL query.
+  layers: LayerConfig[];
   syncIntervalMs: number;
   pollIntervalMs: number;
   pageSize: number;
diff --git a/tests/integration/scheduler/syncManager.spec.ts b/tests/integration/scheduler/syncManager.spec.ts
index 95a3dd1..ac6b376 100644
--- a/tests/integration/scheduler/syncManager.spec.ts
+++ b/tests/integration/scheduler/syncManager.spec.ts
@@ -21,7 +21,7 @@ vi.mock('@src/handler/layerSyncHandler', () => ({
 const TEST_LAYERS = ['layer_alpha', 'layer_beta'];
 
 const syncConfig: SyncConfig = {
-  layers: TEST_LAYERS,
+  layers: TEST_LAYERS.map((layer) => ({ name: layer, query: `query { ${layer} { id } }` })),
   syncIntervalMs: 10,
   pollIntervalMs: 1_000_000,
   pageSize: 100,
diff --git a/tests/unit/dal/layerDataRepository.spec.ts b/tests/unit/dal/layerDataRepository.spec.ts
index 217a9f7..31b1b6c 100644
--- a/tests/unit/dal/layerDataRepository.spec.ts
+++ b/tests/unit/dal/layerDataRepository.spec.ts
@@ -1,13 +1,20 @@
 import type { Logger } from '@map-colonies/js-logger';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
-import { deleteDeprecatedObjects } from '@src/dal/repositories/layerDataRepository';
+import { deleteDeprecatedObjects, insertObjects } from '@src/dal/repositories/layerDataRepository';
 
 const mockExecute = vi.fn();
 const mockWhere = vi.fn().mockReturnValue({ execute: mockExecute });
 const mockFrom = vi.fn().mockReturnValue({ where: mockWhere });
 const mockDelete = vi.fn().mockReturnValue({ from: mockFrom });
 const mockCreateQueryBuilder = vi.fn().mockReturnValue({ delete: mockDelete });
+// insert chain: createQueryBuilder().insert().into().values().orUpdate().execute()
+const mockInsertExecute = vi.fn();
+const mockOrUpdate = vi.fn().mockReturnValue({ execute: mockInsertExecute });
+const mockValues = vi.fn().mockReturnValue({ orUpdate: mockOrUpdate });
+const mockInto = vi.fn().mockReturnValue({ values: mockValues });
+const mockInsert = vi.fn().mockReturnValue({ into: mockInto });
+
 const mockGetRepository = vi.fn().mockReturnValue({ createQueryBuilder: mockCreateQueryBuilder });
 
 vi.mock('@src/dal/connection', () => ({
@@ -95,3 +102,69 @@ describe('deleteDeprecatedObjects', () => {
     expect(mockExecute).not.toHaveBeenCalled();
   });
 });
+
+function makeObject(id: string): LayerObject {
+  return { id, geom: { type: 'Point', coordinates: [0, 0] }, properties: { foo: id } };
+}
+
+describe('insertObjects', () => {
+  let logger: Logger;
+
+  beforeEach(() => {
+    logger = makeLogger();
+    vi.clearAllMocks();
+    mockCreateQueryBuilder.mockReturnValue({ insert: mockInsert });
+    mockInsert.mockReturnValue({ into: mockInto });
+    mockInto.mockReturnValue({ values: mockValues });
+    mockValues.mockReturnValue({ orUpdate: mockOrUpdate });
+    mockOrUpdate.mockReturnValue({ execute: mockInsertExecute });
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('upserts on the (layer_name, id) conflict, overwriting geom and properties', async () => {
+    mockInsertExecute.mockResolvedValueOnce(undefined);
+
+    await insertObjects(logger, 'obstacles', [makeObject('a'), makeObject('b')]);
+
+    expect(mockInsertExecute).toHaveBeenCalledTimes(1);
+    expect(mockOrUpdate).toHaveBeenCalledWith(['geom', 'properties'], ['layer_name', 'id']);
+  });
+
+  it('does nothing when objects is empty', async () => {
+    await insertObjects(logger, 'obstacles', []);
+
+    expect(mockInsertExecute).not.toHaveBeenCalled();
+  });
+
+  it('falls back to per-object upserts when the batch insert throws', async () => {
+    mockInsertExecute.mockRejectedValueOnce(new Error('batch error')).mockResolvedValueOnce(undefined).mockResolvedValueOnce(undefined);
+
+    await insertObjects(logger, 'obstacles', [makeObject('a'), makeObject('b')]);
+
+    // batch attempt + 2 per-object attempts
+    expect(mockInsertExecute).toHaveBeenCalledTimes(3);
+    expect(logger.warn).toHaveBeenCalledWith(
+      expect.objectContaining({ msg: 'Batch insert failed, falling back to per-object inserts', layerName: 'obstacles', count: 2 })
+    );
+  });
+
+  it('logs and continues when an individual upsert also fails', async () => {
+    mockInsertExecute
+      .mockRejectedValueOnce(new Error('batch error'))
+      .mockRejectedValueOnce(new Error('individual error'))
+      .mockResolvedValueOnce(undefined);
+
+    await insertObjects(logger, 'obstacles', [makeObject('a'), makeObject('b')]);
+
+    expect(mockInsertExecute).toHaveBeenCalledTimes(3);
+    expect(logger.error).toHaveBeenCalledWith(
+      expect.objectContaining({ msg: 'Insert failed for object, skipping', layerName: 'obstacles', id: 'a' })
+    );
+    expect(logger.error).toHaveBeenCalledTimes(1);
+
+    expect(mockValues).toHaveBeenLastCalledWith(expect.objectContaining({ layerName: 'obstacles', id: 'b' }));
+  });
+});
diff --git a/tests/unit/externalClients/layersClient.spec.ts b/tests/unit/externalClients/layersClient.spec.ts
index 05403c8..42aaffd 100644
--- a/tests/unit/externalClients/layersClient.spec.ts
+++ b/tests/unit/externalClients/layersClient.spec.ts
@@ -12,7 +12,7 @@ vi.mock('@src/common/syncConfig', () => ({
 }));
 
 const syncConfig: SyncConfig = {
-  layers: ['obstacles'],
+  layers: [{ name: 'obstacles', query: 'query { obstacles { id } }' }],
   syncIntervalMs: 500,
   pollIntervalMs: 600_000,
   pageSize: 100,
diff --git a/tests/unit/handler/layerSyncHandler.spec.ts b/tests/unit/handler/layerSyncHandler.spec.ts
index c19b5a5..9d76f29 100644
--- a/tests/unit/handler/layerSyncHandler.spec.ts
+++ b/tests/unit/handler/layerSyncHandler.spec.ts
@@ -29,7 +29,7 @@ vi.mock('@src/externalClients/layersClient/layersClient', () => ({
 }));
 
 const syncConfig: SyncConfig = {
-  layers: ['obstacles'],
+  layers: [{ name: 'obstacles', query: 'query { obstacles { id } }' }],
   syncIntervalMs: 500,
   pollIntervalMs: 600_000,
   pageSize: 100,