diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/CachingTxnIdFactory.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/CachingTxnIdFactory.java
index d44bb13..6b3b6a0f 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/CachingTxnIdFactory.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/CachingTxnIdFactory.java
@@ -89,7 +89,7 @@
         }
 
         private long nextId() throws BlockExhaustedException {
-            long nextId = id.incrementAndGet();
+            long nextId = id.getAndIncrement();
             if (nextId >= endExclusive && (endExclusive >= start || nextId < start)) {
                 throw BLOCK_EXHAUSTED_EXCEPTION;
             }
diff --git a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/message/TxnIdBlockRequest.java b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/message/TxnIdBlockRequest.java
index b8578ec..4e1c3b1 100644
--- a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/message/TxnIdBlockRequest.java
+++ b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/message/TxnIdBlockRequest.java
@@ -33,7 +33,7 @@
 
 public class TxnIdBlockRequest implements ICcAddressedMessage {
     private static final Logger LOGGER = LogManager.getLogger();
-    private static final int BLOCK_SIZE = 100;
+    private static final int BLOCK_SIZE = 512;
     private static final long serialVersionUID = 1L;
 
     private static BlockingQueue<TxnIdBlockResponse> blockQueue = new LinkedBlockingQueue<>();