aokolnychyi commented on a change in pull request #1862:
URL: https://github.com/apache/iceberg/pull/1862#discussion_r535043116



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File path: api/src/main/java/org/apache/iceberg/IsolationLevel.java
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@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.iceberg;
+
+/**
+ * An isolation level in a table.
+ * <p>
+ * Two isolation levels are supported: serializable and snapshot isolation. 
Both of them provide
+ * a read consistent view of the table to all operations and allow readers to 
see only already
+ * committed data. While serializable is the strongest isolation level in 
databases,
+ * snapshot isolation is beneficial for environments with many concurrent 
writers.
+ * <p>
+ * The serializable isolation level guarantees that an ongoing 
UPDATE/DELETE/MERGE operation
+ * fails if a concurrent transaction commits a new file that might contain 
rows matching
+ * the condition used in UPDATE/DELETE/MERGE. For example, if there is an 
ongoing update
+ * on a subset of rows and a concurrent transaction adds a new file with 
records
+ * that potentially match the update condition, the update operation must fail 
under
+ * the serializable isolation but can still commit under the snapshot 
isolation.
+ */
+public enum IsolationLevel {

Review comment:
       Sound good to me.




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