diff --git a/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedEntryDAO.java b/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedEntryDAO.java
index 4712e957..0cf2962b 100644
--- a/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedEntryDAO.java
+++ b/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedEntryDAO.java
@@ -1,6 +1,7 @@
 package com.commafeed.backend.dao;
 
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -11,6 +12,7 @@ import jakarta.persistence.EntityManager;
 import com.commafeed.backend.model.Feed;
 import com.commafeed.backend.model.FeedEntry;
 import com.commafeed.backend.model.QFeedEntry;
+import com.google.common.collect.Lists;
 import com.querydsl.core.Tuple;
 import com.querydsl.core.types.dsl.NumberExpression;
 import com.querydsl.jpa.impl.JPAQuery;
@@ -19,6 +21,7 @@ import com.querydsl.jpa.impl.JPAQuery;
 public class FeedEntryDAO extends GenericDAO<FeedEntry> {
 
 	private static final QFeedEntry ENTRY = QFeedEntry.feedEntry;
+	private static final int IN_CLAUSE_BATCH_SIZE = 1000;
 
 	public FeedEntryDAO(EntityManager entityManager) {
 		super(entityManager, FeedEntry.class);
@@ -28,8 +31,16 @@ public class FeedEntryDAO extends GenericDAO<FeedEntry> {
 		return query().select(ENTRY).from(ENTRY).where(ENTRY.guidHash.eq(guidHash), ENTRY.feed.eq(feed)).limit(1).fetchOne();
 	}
 
-	public Set<String> findExistingGuids(Feed feed) {
-		return new HashSet<>(query().select(ENTRY.guidHash).from(ENTRY).where(ENTRY.feed.eq(feed)).fetch());
+	public Set<String> findExistingGuids(Feed feed, Set<String> guidHashes) {
+		if (guidHashes.isEmpty()) {
+			return Set.of();
+		}
+
+		Set<String> result = new HashSet<>();
+		for (List<String> batch : Lists.partition(new ArrayList<>(guidHashes), IN_CLAUSE_BATCH_SIZE)) {
+			result.addAll(query().select(ENTRY.guidHash).from(ENTRY).where(ENTRY.feed.eq(feed), ENTRY.guidHash.in(batch)).fetch());
+		}
+		return result;
 	}
 
 	public List<FeedCapacity> findFeedsExceedingCapacity(long maxCapacity, long max, boolean keepStarredEntries) {
diff --git a/commafeed-server/src/main/java/com/commafeed/backend/feed/FeedRefreshUpdater.java b/commafeed-server/src/main/java/com/commafeed/backend/feed/FeedRefreshUpdater.java
index 8bd1e42b..7440c3fa 100644
--- a/commafeed-server/src/main/java/com/commafeed/backend/feed/FeedRefreshUpdater.java
+++ b/commafeed-server/src/main/java/com/commafeed/backend/feed/FeedRefreshUpdater.java
@@ -129,8 +129,16 @@ public class FeedRefreshUpdater {
 		Map<FeedSubscription, List<FeedEntry>> insertedUnreadEntriesBySubscription = new HashMap<>();
 
 		if (!entries.isEmpty()) {
-			Set<String> existingGuids = unitOfWork.call(() -> feedEntryDAO.findExistingGuids(feed));
-			List<Entry> newEntries = entries.stream().filter(e -> !existingGuids.contains(Digests.sha1Hex(e.guid()))).toList();
+			Map<String, Entry> entriesByGuidHash = new HashMap<>();
+			for (Entry entry : entries) {
+				entriesByGuidHash.put(Digests.sha1Hex(entry.guid()), entry);
+			}
+			Set<String> existingGuids = unitOfWork.call(() -> feedEntryDAO.findExistingGuids(feed, entriesByGuidHash.keySet()));
+			List<Entry> newEntries = entriesByGuidHash.entrySet()
+					.stream()
+					.filter(e -> !existingGuids.contains(e.getKey()))
+					.map(Map.Entry::getValue)
+					.toList();
 
 			List<FeedSubscription> subscriptions = null;
 			for (Entry entry : newEntries) {
diff --git a/commafeed-server/src/test/java/com/commafeed/integration/rest/LargeDatasetIT.java b/commafeed-server/src/test/java/com/commafeed/integration/rest/LargeDatasetIT.java
index ead46bb3..40105f53 100644
--- a/commafeed-server/src/test/java/com/commafeed/integration/rest/LargeDatasetIT.java
+++ b/commafeed-server/src/test/java/com/commafeed/integration/rest/LargeDatasetIT.java
@@ -30,6 +30,8 @@ class LargeDatasetIT extends BaseIT {
 	private static final int ENTRIES_PER_FEED = 20;
 	private static final int TOTAL_ENTRIES = FEED_COUNT * ENTRIES_PER_FEED;
 
+	private Long firstSubscriptionId;
+
 	@BeforeEach
 	void setup() {
 		initialSetup(TestConstants.ADMIN_USERNAME, TestConstants.ADMIN_PASSWORD);
@@ -39,7 +41,10 @@ class LargeDatasetIT extends BaseIT {
 			String path = "/feed/" + i;
 			getMockServerClient().when(HttpRequest.request().withMethod("GET").withPath(path))
 					.respond(HttpResponse.response().withBody(generateFeed(i)).withContentType(MediaType.APPLICATION_XML));
-			subscribe("http://localhost:" + getMockServerClient().getPort() + path);
+			Long subscriptionId = subscribe("http://localhost:" + getMockServerClient().getPort() + path);
+			if (i == 0) {
+				firstSubscriptionId = subscriptionId;
+			}
 		}
 
 		Awaitility.await().atMost(Duration.ofSeconds(60)).until(() -> getAllEntries().getEntries().size(), count -> count >= TOTAL_ENTRIES);
@@ -66,6 +71,18 @@ class LargeDatasetIT extends BaseIT {
 		Assertions.assertTrue(after.getEntries().stream().allMatch(Entry::isRead));
 	}
 
+	@Test
+	void refreshDoesNotCreateDuplicateEntries() {
+		Assertions.assertEquals(TOTAL_ENTRIES, getAllEntries().getEntries().size());
+		Instant threshold = Instant.now().minus(Duration.ofSeconds(1));
+		forceRefreshAllFeeds();
+
+		Awaitility.await()
+				.atMost(Duration.ofSeconds(15))
+				.until(() -> getSubscription(firstSubscriptionId), f -> f.getLastRefresh().isAfter(threshold));
+		Assertions.assertEquals(TOTAL_ENTRIES, getAllEntries().getEntries().size());
+	}
+
 	@Test
 	void paginationHasMore() {
 		Entries firstPage = RestAssured.given()