Index: oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/FileBlobStore.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/FileBlobStore.java	(revision e7f6d26b5abe0cc27ad47730410e0a7d6061a74e)
+++ oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/FileBlobStore.java	(date 1522920806000)
@@ -109,6 +109,7 @@
     protected synchronized void storeBlock(byte[] digest, int level, byte[] data) throws IOException {
         File f = getFile(digest, false);
         if (f.exists()) {
+            FileUtils.touch(f);
             return;
         }
         File parent = f.getParentFile();
Index: oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/MemoryBlobStore.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/MemoryBlobStore.java	(revision e7f6d26b5abe0cc27ad47730410e0a7d6061a74e)
+++ oak-blob/src/main/java/org/apache/jackrabbit/oak/spi/blob/MemoryBlobStore.java	(date 1522923222000)
@@ -33,6 +33,7 @@
 
     private HashMap<BlockId, byte[]> map = new HashMap<BlockId, byte[]>();
     private HashMap<BlockId, byte[]> old = new HashMap<BlockId, byte[]>();
+    private HashMap<BlockId, Long> timestamps = new HashMap<BlockId, Long>();
     private boolean mark;
 
     @Override
@@ -46,7 +47,9 @@
 
     @Override
     protected synchronized void storeBlock(byte[] digest, int level, byte[] data) {
-        map.put(new BlockId(digest, 0), data);
+        BlockId id =  new BlockId(digest, 0);
+        map.put(id, data);
+        timestamps.put(id, System.currentTimeMillis());
     }
 
     @Override
@@ -90,8 +93,11 @@
         for (String chunkId : chunkIds) {
             BlockId id = new BlockId(StringUtils.convertHexToBytes(chunkId), 0);
             if (map.containsKey(id)) {
-                map.remove(id);
-                count++;
+                if (maxLastModifiedTime == 0 || (maxLastModifiedTime > 0 && maxLastModifiedTime > timestamps.get(id))) {
+                    map.remove(id);
+                    timestamps.remove(id);
+                    count++;
+                }
             } else if (old.containsKey(id)) {
                 old.remove(id);
                 count++;
Index: oak-blob/src/test/java/org/apache/jackrabbit/oak/spi/blob/AbstractBlobStoreTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-blob/src/test/java/org/apache/jackrabbit/oak/spi/blob/AbstractBlobStoreTest.java	(revision e7f6d26b5abe0cc27ad47730410e0a7d6061a74e)
+++ oak-blob/src/test/java/org/apache/jackrabbit/oak/spi/blob/AbstractBlobStoreTest.java	(date 1522923413000)
@@ -445,6 +445,28 @@
         assertEquals(ids.size(), count);
     }
 
+    @Test
+    public void deleteUpdatedBlob() throws Exception {
+        String id = store.writeBlob(randomStream(0, getArtifactSize()));
+        Thread.sleep(100);
+
+        long beforeUpdateTime = System.currentTimeMillis();
+
+        Thread.sleep(200);
+
+        // Should update the timestamp
+        String id2 = store.writeBlob(randomStream(0, getArtifactSize()));
+        assertEquals(id, id2);
+
+        Set<String> chunks = Sets.newHashSet();
+        Iterator<String> iter = store.resolveChunks(id.toString());
+        while (iter.hasNext()) {
+            chunks.add(iter.next());
+        }
+        long count = store.countDeleteChunks(Lists.newArrayList(chunks), beforeUpdateTime);
+        assertEquals("Deleted updated blobs", 0, count);
+    }
+
     @Test
     public void uploadCallback() throws Exception {
         assumeTrue(supportsStatsCollection());
Index: oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/mongo/MongoBlobStore.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/mongo/MongoBlobStore.java	(revision e7f6d26b5abe0cc27ad47730410e0a7d6061a74e)
+++ oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/mongo/MongoBlobStore.java	(date 1522923584000)
@@ -103,10 +103,12 @@
         try {
             getBlobCollection().insertOne(mongoBlob);
         } catch (DuplicateKeyException e) {
-            // the same block was already stored before: ignore
+            // the same block was already stored before: update timestamp
+            updateTimestamp(id, System.currentTimeMillis());
         } catch (MongoException e) {
             if (e.getCode() == DUPLICATE_KEY_ERROR_CODE) {
-                // the same block was already stored before: ignore
+                // the same block was already stored before: update timestamp
+                updateTimestamp(id, System.currentTimeMillis());
             } else {
                 throw new IOException(e.getMessage(), e);
             }
@@ -158,9 +160,13 @@
             return;
         }
         String id = StringUtils.convertBytesToHex(blockId.getDigest());
+        updateTimestamp(id, minLastModified);
+    }
+
+    private void updateTimestamp(String id, long minLastModified) {
         Bson query = getBlobQuery(id, minLastModified);
         Bson update = new BasicDBObject("$set",
-                new BasicDBObject(MongoBlob.KEY_LAST_MOD, System.currentTimeMillis()));
+            new BasicDBObject(MongoBlob.KEY_LAST_MOD, System.currentTimeMillis()));
         getBlobCollection().updateOne(query, update);
     }