diff --git a/pom.xml b/pom.xml
index 9361209..aa77247 100644
--- a/pom.xml
+++ b/pom.xml
@@ -138,7 +138,7 @@
     <dependency>
       <groupId>org.rocksdb</groupId>
       <artifactId>rocksdbjni</artifactId>
-      <version>6.15.2</version>
+      <version>6.15.5</version>
     </dependency>
     <dependency>
       <groupId>org.apache.lucene</groupId>
diff --git a/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionaryDeep.java b/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionaryDeep.java
index 6966910..bc70f23 100644
--- a/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionaryDeep.java
+++ b/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionaryDeep.java
@@ -249,10 +249,9 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 		} else {
 			return dictionary
 					.getRangeKeyPrefixes(resolveSnapshot(snapshot), range, keyPrefix.length + keySuffixLength)
-					.flatMapSequential(groupKeyWithExt -> {
-						byte[] groupKeyWithoutExt = removeExtFromFullKey(groupKeyWithExt);
+					.flatMapSequential(groupKeyWithoutExt -> {
 						byte[] groupSuffix = this.stripPrefix(groupKeyWithoutExt);
-						assert subStageKeysConsistency(groupKeyWithExt.length);
+						assert subStageKeysConsistency(groupKeyWithoutExt.length + keyExtLength);
 						return this.subStageGetter
 								.subStage(dictionary,
 										snapshot,
diff --git a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
index 43eb4b5..62cf658 100644
--- a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
+++ b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
@@ -48,6 +48,8 @@ public class LLLocalDictionary implements LLDictionary {
 	static final int CAPPED_WRITE_BATCH_CAP = 50000; // 50K operations
 	static final int MULTI_GET_WINDOW = 500;
 	static final WriteOptions BATCH_WRITE_OPTIONS = new WriteOptions().setLowPri(true);
+	static final boolean PREFER_ALWAYS_SEEK_TO_FIRST = true;
+	static final boolean ALWAYS_VERIFY_CHECKSUMS = true;
 
 	private static final int STRIPES = 512;
 	private static final byte[] FIRST_KEY = new byte[]{};
@@ -167,7 +169,7 @@ public class LLLocalDictionary implements LLDictionary {
 		return Mono
 				.fromCallable(() -> {
 					var readOpts = resolveSnapshot(snapshot);
-					readOpts.setVerifyChecksums(false);
+					readOpts.setVerifyChecksums(ALWAYS_VERIFY_CHECKSUMS);
 					readOpts.setFillCache(false);
 					if (range.hasMin()) {
 						readOpts.setIterateLowerBound(new Slice(range.getMin()));
@@ -698,7 +700,7 @@ public class LLLocalDictionary implements LLDictionary {
 		return Mono
 				.<Void>fromCallable(() -> {
 					var readOpts = getReadOptions(null);
-					readOpts.setVerifyChecksums(false);
+					readOpts.setVerifyChecksums(ALWAYS_VERIFY_CHECKSUMS);
 
 					// readOpts.setIgnoreRangeDeletions(true);
 					readOpts.setFillCache(false);
@@ -752,7 +754,7 @@ public class LLLocalDictionary implements LLDictionary {
 					.fromCallable(() -> {
 						var readOpts = resolveSnapshot(snapshot);
 						readOpts.setFillCache(false);
-						readOpts.setVerifyChecksums(false);
+						readOpts.setVerifyChecksums(ALWAYS_VERIFY_CHECKSUMS);
 						if (range.hasMin()) {
 							readOpts.setIterateLowerBound(new Slice(range.getMin()));
 						}
@@ -840,12 +842,8 @@ public class LLLocalDictionary implements LLDictionary {
 			}
 		} else {
 			rocksdbSnapshot.setFillCache(false);
-			rocksdbSnapshot.setVerifyChecksums(false);
-			rocksdbSnapshot.setPinData(false);
+			rocksdbSnapshot.setVerifyChecksums(ALWAYS_VERIFY_CHECKSUMS);
 			rocksdbSnapshot.setIgnoreRangeDeletions(false);
-			if (snapshot == null) {
-				rocksdbSnapshot.setTailing(true);
-			}
 			long count = 0;
 			try (RocksIterator iter = db.newIterator(cfh, rocksdbSnapshot)) {
 				iter.seekToFirst();
@@ -862,7 +860,7 @@ public class LLLocalDictionary implements LLDictionary {
 	private long exactSizeAll(@Nullable LLSnapshot snapshot) {
 		var readOpts = resolveSnapshot(snapshot);
 		readOpts.setFillCache(false);
-		readOpts.setVerifyChecksums(false);
+		readOpts.setVerifyChecksums(ALWAYS_VERIFY_CHECKSUMS);
 
 		long count = 0;
 		try (RocksIterator iter = db.newIterator(cfh, readOpts)) {
@@ -887,7 +885,7 @@ public class LLLocalDictionary implements LLDictionary {
 						readOpts.setIterateUpperBound(new Slice(range.getMax()));
 					}
 					try (RocksIterator iter = db.newIterator(cfh, readOpts)) {
-						if (range.hasMin()) {
+						if (!LLLocalDictionary.PREFER_ALWAYS_SEEK_TO_FIRST && range.hasMin()) {
 							iter.seek(range.getMin());
 						} else {
 							iter.seekToFirst();
diff --git a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneGroupedReactiveIterator.java b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneGroupedReactiveIterator.java
index af7db42..2967698 100644
--- a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneGroupedReactiveIterator.java
+++ b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneGroupedReactiveIterator.java
@@ -53,7 +53,7 @@ public abstract class LLLocalLuceneGroupedReactiveIterator<T> {
 							readOptions.setIterateUpperBound(new Slice(range.getMax()));
 						}
 						var rocksIterator = db.newIterator(cfh, readOptions);
-						if (range.hasMin()) {
+						if (!LLLocalDictionary.PREFER_ALWAYS_SEEK_TO_FIRST && range.hasMin()) {
 							rocksIterator.seek(range.getMin());
 						} else {
 							rocksIterator.seekToFirst();
diff --git a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneKeyPrefixesReactiveIterator.java b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneKeyPrefixesReactiveIterator.java
index 7e591cf..2ebb0fc 100644
--- a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneKeyPrefixesReactiveIterator.java
+++ b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneKeyPrefixesReactiveIterator.java
@@ -39,6 +39,7 @@ public class LLLocalLuceneKeyPrefixesReactiveIterator {
 		return Flux
 				.generate(() -> {
 					synchronized (this) {
+						System.out.println(Thread.currentThread().getName());
 						var readOptions = new ReadOptions(this.readOptions);
 						readOptions.setFillCache(range.hasMin() && range.hasMax());
 						if (range.hasMin()) {
@@ -48,7 +49,7 @@ public class LLLocalLuceneKeyPrefixesReactiveIterator {
 							readOptions.setIterateUpperBound(new Slice(range.getMax()));
 						}
 						var rocksIterator = db.newIterator(cfh, readOptions);
-						if (range.hasMin()) {
+						if (!LLLocalDictionary.PREFER_ALWAYS_SEEK_TO_FIRST && range.hasMin()) {
 							rocksIterator.seek(range.getMin());
 						} else {
 							rocksIterator.seekToFirst();
@@ -57,6 +58,7 @@ public class LLLocalLuceneKeyPrefixesReactiveIterator {
 					}
 				}, (rocksIterator, sink) -> {
 					synchronized (this) {
+						System.out.println(Thread.currentThread().getName());
 						byte[] firstGroupKey = null;
 
 						while (rocksIterator.isValid()) {
diff --git a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneReactiveIterator.java b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneReactiveIterator.java
index 6944299..1f709a0 100644
--- a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneReactiveIterator.java
+++ b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalLuceneReactiveIterator.java
@@ -43,7 +43,7 @@ public abstract class LLLocalLuceneReactiveIterator<T> {
 							readOptions.setIterateUpperBound(new Slice(range.getMax()));
 						}
 						var rocksIterator = db.newIterator(cfh, readOptions);
-						if (range.hasMin()) {
+						if (!LLLocalDictionary.PREFER_ALWAYS_SEEK_TO_FIRST && range.hasMin()) {
 							rocksIterator.seek(range.getMin());
 						} else {
 							rocksIterator.seekToFirst();