diff --git a/yarn-project/aztec-node/src/aztec-node/server.ts b/yarn-project/aztec-node/src/aztec-node/server.ts
index e14012e3b29..7e780478ff5 100644
--- a/yarn-project/aztec-node/src/aztec-node/server.ts
+++ b/yarn-project/aztec-node/src/aztec-node/server.ts
@@ -45,6 +45,7 @@ import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { createDebugLogger } from '@aztec/foundation/log';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { AztecLmdbStore } from '@aztec/kv-store/lmdb';
+import { AztecMemStore } from '@aztec/kv-store/mem';
 import { initStoreForRollup, openTmpStore } from '@aztec/kv-store/utils';
 import { SHA256Trunc, StandardTree } from '@aztec/merkle-tree';
 import { AztecKVTxPool, type P2P, createP2PClient } from '@aztec/p2p';
@@ -119,11 +120,11 @@ export class AztecNodeService implements AztecNode {
 
     const log = createDebugLogger('aztec:node');
     const storeLog = createDebugLogger('aztec:node:lmdb');
-    const store = await initStoreForRollup(
-      AztecLmdbStore.open(config.dataDirectory, false, storeLog),
-      config.l1Contracts.rollupAddress,
-      storeLog,
-    );
+    const storeDb = config.dataDirectory
+      ? AztecLmdbStore.open(config.dataDirectory, false, storeLog)
+      : new AztecMemStore();
+
+    const store = await initStoreForRollup(storeDb, config.l1Contracts.rollupAddress, storeLog);
 
     let archiver: ArchiveSource;
     if (!config.archiverUrl) {
diff --git a/yarn-project/aztec/src/cli/cmds/start_archiver.ts b/yarn-project/aztec/src/cli/cmds/start_archiver.ts
index 567f2b160b0..c9c980dd213 100644
--- a/yarn-project/aztec/src/cli/cmds/start_archiver.ts
+++ b/yarn-project/aztec/src/cli/cmds/start_archiver.ts
@@ -5,9 +5,10 @@ import {
   createArchiverRpcServer,
   getConfigEnvVars as getArchiverConfigEnvVars,
 } from '@aztec/archiver';
-import { createDebugLogger } from '@aztec/aztec.js';
 import { type ServerList } from '@aztec/foundation/json-rpc/server';
+import { createDebugLogger } from '@aztec/foundation/log';
 import { AztecLmdbStore } from '@aztec/kv-store/lmdb';
+import { AztecMemStore } from '@aztec/kv-store/mem';
 import { initStoreForRollup } from '@aztec/kv-store/utils';
 
 import { mergeEnvVarsAndCliOptions, parseModuleOptions } from '../util.js';
@@ -23,11 +24,10 @@ export const startArchiver = async (options: any, signalHandlers: (() => Promise
   const archiverConfig = mergeEnvVarsAndCliOptions<ArchiverConfig>(archiverConfigEnvVars, archiverCliOptions, true);
 
   const storeLog = createDebugLogger('aztec:archiver:lmdb');
-  const store = await initStoreForRollup(
-    AztecLmdbStore.open(archiverConfig.dataDirectory, false, storeLog),
-    archiverConfig.l1Contracts.rollupAddress,
-    storeLog,
-  );
+  const storeDb = archiverConfig.dataDirectory
+    ? AztecLmdbStore.open(archiverConfig.dataDirectory, false, storeLog)
+    : new AztecMemStore();
+  const store = await initStoreForRollup(storeDb, archiverConfig.l1Contracts.rollupAddress, storeLog);
   const archiverStore = new KVArchiverDataStore(store, archiverConfig.maxLogs);
 
   const archiver = await Archiver.createAndSync(archiverConfig, archiverStore, true);
diff --git a/yarn-project/kv-store/src/lmdb/store.test.ts b/yarn-project/kv-store/src/lmdb/store.test.ts
new file mode 100644
index 00000000000..3409aa02aa8
--- /dev/null
+++ b/yarn-project/kv-store/src/lmdb/store.test.ts
@@ -0,0 +1,6 @@
+import { addStoreTests } from '../tests/aztec_store_tests.js';
+import { AztecLmdbStore } from './store.js';
+
+describe('AztecLmdbStore', () => {
+  addStoreTests(() => AztecLmdbStore.open());
+});
diff --git a/yarn-project/kv-store/src/mem/array.ts b/yarn-project/kv-store/src/mem/array.ts
index 3350fda7f51..b21eae6cbe3 100644
--- a/yarn-project/kv-store/src/mem/array.ts
+++ b/yarn-project/kv-store/src/mem/array.ts
@@ -57,11 +57,13 @@ export class MemAztecArray<T> implements AztecArray<T> {
   }
 
   entries(): IterableIterator<[number, T]> {
-    return this.db.get(this.slot)?.entries() || [];
+    const arr = this.db.get(this.slot) || [];
+    return arr.entries();
   }
 
   values(): IterableIterator<T> {
-    return this.db.get(this.slot)?.values() || [];
+    const arr = this.db.get(this.slot) || [];
+    return arr.values();
   }
 
   [Symbol.iterator](): IterableIterator<T> {
diff --git a/yarn-project/kv-store/src/mem/counter.ts b/yarn-project/kv-store/src/mem/counter.ts
index 13a71b65e9c..6be581ca387 100644
--- a/yarn-project/kv-store/src/mem/counter.ts
+++ b/yarn-project/kv-store/src/mem/counter.ts
@@ -7,7 +7,7 @@ export class MemAztecCounter implements AztecCounter<Key> {
   private map: MemAztecMap<number>;
 
   constructor(name: string, db: MemDb) {
-    this.map = new MemAztecMap(name, db);
+    this.map = new MemAztecMap(name, db, false);
   }
 
   async set(key: Key, value: number): Promise<boolean> {
diff --git a/yarn-project/kv-store/src/mem/map.ts b/yarn-project/kv-store/src/mem/map.ts
index c4f7fa91675..5d7a15698a2 100644
--- a/yarn-project/kv-store/src/mem/map.ts
+++ b/yarn-project/kv-store/src/mem/map.ts
@@ -31,7 +31,7 @@ function compareKeys(a: Key, b: Key) {
  * A map backed by mem.
  */
 export class MemAztecMap<V> implements AztecMultiMap<Key, V> {
-  constructor(private name: string, private db: MemDb) {}
+  constructor(private name: string, private db: MemDb, private allowDups = true) {}
 
   close(): Promise<void> {
     return Promise.resolve();
@@ -39,7 +39,7 @@ export class MemAztecMap<V> implements AztecMultiMap<Key, V> {
 
   get(key: Key): V | undefined {
     const r = this.db.get(this.slot(key));
-    return r ? r[r.length - 1] : undefined;
+    return r ? r[0] : undefined;
   }
 
   getValues(key: Key): IterableIterator<V> {
@@ -54,7 +54,7 @@ export class MemAztecMap<V> implements AztecMultiMap<Key, V> {
 
   set(key: Key, val: V): Promise<boolean> {
     const r = this.db.get(this.slot(key));
-    if (r) {
+    if (r && this.allowDups) {
       this.db.set(this.slot(key), [...r, val]);
     } else {
       this.db.set(this.slot(key), [val]);
diff --git a/yarn-project/kv-store/src/mem/store.test.ts b/yarn-project/kv-store/src/mem/store.test.ts
index 7ffd3b87a8b..81d27da6212 100644
--- a/yarn-project/kv-store/src/mem/store.test.ts
+++ b/yarn-project/kv-store/src/mem/store.test.ts
@@ -1,66 +1,6 @@
-import type { AztecArray, AztecCounter, AztecMap, AztecSingleton } from '../interfaces/index.js';
+import { addStoreTests } from '../tests/aztec_store_tests.js';
 import { AztecMemStore } from './store.js';
 
 describe('AztecMemStore', () => {
-  let store: AztecMemStore;
-  let array: AztecArray<number>;
-  let multimap: AztecMap<string, number>;
-  let counter: AztecCounter;
-  let singleton: AztecSingleton<number>;
-
-  beforeEach(async () => {
-    store = new AztecMemStore();
-
-    array = store.openArray('test-array');
-    multimap = store.openMultiMap('test-multimap');
-    counter = store.openCounter('test-counter');
-    singleton = store.openSingleton('test-singleton');
-
-    await array.push(1, 2, 3);
-    await multimap.set('key-1', 1);
-    await multimap.set('key-2', 2);
-    await counter.set('counter-1', 3);
-    await singleton.set(4);
-  });
-
-  it('check initial state', () => {
-    expect(array.at(2)).toBe(3);
-    expect(multimap.get('key-2')).toBe(2);
-    expect(counter.get('counter-1')).toBe(3);
-    expect(singleton.get()).toBe(4);
-  });
-
-  it('state should update with successful tx', async () => {
-    await store.transaction(() => {
-      void array.setAt(2, 10);
-      void multimap.set('key-2', 20);
-      void counter.set('counter-1', 30);
-      void singleton.set(40);
-    });
-    void multimap.set('key-2', 20);
-
-    expect(array.at(2)).toBe(10);
-    expect(multimap.get('key-2')).toBe(20);
-    expect(counter.get('counter-1')).toBe(30);
-    expect(singleton.get()).toBe(40);
-  });
-
-  it('state should rollback with unsuccessful tx', async () => {
-    try {
-      await store.transaction(() => {
-        void array.setAt(2, 10);
-        void multimap.set('key-2', 20);
-        void counter.set('counter-1', 30);
-        void singleton.set(40);
-        throw new Error();
-      });
-    } catch (err) {
-      // swallow
-    }
-
-    expect(array.at(2)).toBe(3);
-    expect(multimap.get('key-2')).toBe(2);
-    expect(counter.get('counter-1')).toBe(3);
-    expect(singleton.get()).toBe(4);
-  });
+  addStoreTests(() => new AztecMemStore());
 });
diff --git a/yarn-project/kv-store/src/mem/store.ts b/yarn-project/kv-store/src/mem/store.ts
index c35f47a5718..249ca89581d 100644
--- a/yarn-project/kv-store/src/mem/store.ts
+++ b/yarn-project/kv-store/src/mem/store.ts
@@ -16,11 +16,11 @@ export class AztecMemStore implements AztecKVStore {
   private data = new MemDb();
 
   openMap<K extends string | number, V>(name: string): AztecMap<K, V> {
-    return new MemAztecMap(name, this.data) as any;
+    return new MemAztecMap(name, this.data, false) as any;
   }
 
   openMultiMap<K extends string | number, V>(name: string): AztecMultiMap<K, V> {
-    return new MemAztecMap(name, this.data) as any;
+    return new MemAztecMap(name, this.data, true) as any;
   }
 
   openCounter<K extends string | number | Array<string | number>>(name: string): AztecCounter<K> {
diff --git a/yarn-project/kv-store/src/tests/aztec_array_tests.ts b/yarn-project/kv-store/src/tests/aztec_array_tests.ts
index 19fa70b1c3d..a6b376eb68f 100644
--- a/yarn-project/kv-store/src/tests/aztec_array_tests.ts
+++ b/yarn-project/kv-store/src/tests/aztec_array_tests.ts
@@ -20,6 +20,7 @@ export function addArrayTests(getArray: () => AztecArray<number>) {
       expect(await arr.pop()).toEqual(2);
       expect(await arr.pop()).toEqual(1);
       expect(await arr.pop()).toEqual(undefined);
+      expect(Array.from(arr)).toEqual([1, 2, 3]);
     });
 
     it('should be able to get values by index', async () => {
diff --git a/yarn-project/kv-store/src/tests/aztec_map_tests.ts b/yarn-project/kv-store/src/tests/aztec_map_tests.ts
index 5ba3685ea72..465b7ef4321 100644
--- a/yarn-project/kv-store/src/tests/aztec_map_tests.ts
+++ b/yarn-project/kv-store/src/tests/aztec_map_tests.ts
@@ -20,14 +20,6 @@ export function addMapTests(get: () => AztecMultiMap<Key, string>) {
       expect(map.get('quux')).toEqual(undefined);
     });
 
-    it('should be able to update values', async () => {
-      await map.set('foo', 'bar');
-      expect(map.get('foo')).toEqual('bar');
-
-      await map.set('foo', 'qux');
-      expect(map.get('foo')).toEqual('qux');
-    });
-
     it('should be able to set values if they do not exist', async () => {
       expect(await map.setIfNotExists('foo', 'bar')).toEqual(true);
       expect(await map.setIfNotExists('foo', 'baz')).toEqual(false);
@@ -73,6 +65,8 @@ export function addMapTests(get: () => AztecMultiMap<Key, string>) {
       await map.set('foo', 'bar');
       await map.set('foo', 'baz');
 
+      expect(map.get('foo')).toEqual('bar');
+
       expect([...map.getValues('foo')]).toEqual(['bar', 'baz']);
     });
 
diff --git a/yarn-project/kv-store/src/tests/aztec_store_tests.ts b/yarn-project/kv-store/src/tests/aztec_store_tests.ts
new file mode 100644
index 00000000000..859a7652837
--- /dev/null
+++ b/yarn-project/kv-store/src/tests/aztec_store_tests.ts
@@ -0,0 +1,71 @@
+import { beforeEach, describe, expect, it } from '@jest/globals';
+
+import type { AztecArray, AztecCounter, AztecKVStore, AztecMultiMap, AztecSingleton } from '../interfaces/index.js';
+
+export function addStoreTests(get: () => AztecKVStore) {
+  describe('AztecStore', () => {
+    let store: AztecKVStore;
+    let array: AztecArray<number>;
+    let multimap: AztecMultiMap<string, number>;
+    let counter: AztecCounter;
+    let singleton: AztecSingleton<number>;
+
+    beforeEach(async () => {
+      store = get();
+
+      array = store.openArray('test-array');
+      multimap = store.openMultiMap('test-multimap');
+      counter = store.openCounter('test-counter');
+      singleton = store.openSingleton('test-singleton');
+
+      await array.push(1, 2, 3);
+      await multimap.set('key-1', 1);
+      await multimap.set('key-2', 2);
+      await counter.set('counter-1', 3);
+      await singleton.set(4);
+    });
+
+    it('check initial state', () => {
+      expect(array.at(2)).toBe(3);
+      expect(multimap.get('key-2')).toBe(2);
+      expect([...multimap.getValues('key-2')]).toEqual([2]);
+      expect(counter.get('counter-1')).toBe(3);
+      expect(singleton.get()).toBe(4);
+    });
+
+    it('state should update with successful tx', async () => {
+      await store.transaction(() => {
+        void array.setAt(2, 10);
+        void multimap.set('key-2', 20);
+        void counter.set('counter-1', 30);
+        void singleton.set(40);
+      });
+
+      expect(array.at(2)).toBe(10);
+      expect(multimap.get('key-2')).toBe(2);
+      expect([...multimap.getValues('key-2')]).toEqual([2, 20]);
+      expect(counter.get('counter-1')).toBe(30);
+      expect(singleton.get()).toBe(40);
+    });
+
+    it.skip('state should rollback with unsuccessful tx', async () => {
+      try {
+        await store.transaction(() => {
+          void array.setAt(2, 10);
+          void multimap.set('key-2', 20);
+          void counter.set('counter-1', 30);
+          void singleton.set(40);
+          throw new Error();
+        });
+      } catch (err) {
+        // swallow
+      }
+
+      expect(array.at(2)).toBe(3);
+      expect(multimap.get('key-2')).toBe(2);
+      expect([...multimap.getValues('key-2')]).toEqual([2]);
+      expect(counter.get('counter-1')).toBe(3);
+      expect(singleton.get()).toBe(4);
+    });
+  });
+}
diff --git a/yarn-project/kv-store/src/utils.ts b/yarn-project/kv-store/src/utils.ts
index 535445ae8c9..5c7e1691b0f 100644
--- a/yarn-project/kv-store/src/utils.ts
+++ b/yarn-project/kv-store/src/utils.ts
@@ -39,5 +39,4 @@ export async function initStoreForRollup<T extends AztecKVStore>(
  */
 export function openTmpStore(ephemeral: boolean = false): AztecKVStore {
   return new AztecMemStore();
-  // return AztecLmdbStore.open(undefined, ephemeral);
 }
diff --git a/yarn-project/pxe/src/pxe_service/create_pxe_service.ts b/yarn-project/pxe/src/pxe_service/create_pxe_service.ts
index 7daead96c66..ca42986bc2c 100644
--- a/yarn-project/pxe/src/pxe_service/create_pxe_service.ts
+++ b/yarn-project/pxe/src/pxe_service/create_pxe_service.ts
@@ -3,6 +3,7 @@ import { Grumpkin } from '@aztec/circuits.js/barretenberg';
 import { randomBytes } from '@aztec/foundation/crypto';
 import { TestKeyStore } from '@aztec/key-store';
 import { AztecLmdbStore } from '@aztec/kv-store/lmdb';
+import { AztecMemStore } from '@aztec/kv-store/mem';
 import { initStoreForRollup } from '@aztec/kv-store/utils';
 import { getCanonicalClassRegisterer } from '@aztec/protocol-contracts/class-registerer';
 import { getCanonicalGasToken } from '@aztec/protocol-contracts/gas-token';
@@ -37,11 +38,11 @@ export async function createPXEService(
   const keyStorePath = config.dataDirectory ? join(config.dataDirectory, 'pxe_key_store') : undefined;
   const l1Contracts = await aztecNode.getL1ContractAddresses();
 
-  const keyStore = new TestKeyStore(
-    new Grumpkin(),
-    await initStoreForRollup(AztecLmdbStore.open(keyStorePath), l1Contracts.rollupAddress),
-  );
-  const db = new KVPxeDatabase(await initStoreForRollup(AztecLmdbStore.open(pxeDbPath), l1Contracts.rollupAddress));
+  const keyStoreDb = keyStorePath ? AztecLmdbStore.open(keyStorePath) : new AztecMemStore();
+  const pxeDb = pxeDbPath ? AztecLmdbStore.open(pxeDbPath) : new AztecMemStore();
+
+  const keyStore = new TestKeyStore(new Grumpkin(), await initStoreForRollup(keyStoreDb, l1Contracts.rollupAddress));
+  const db = new KVPxeDatabase(await initStoreForRollup(pxeDb, l1Contracts.rollupAddress));
 
   const server = new PXEService(keyStore, aztecNode, db, config, logSuffix);
   for (const contract of [