HDDS-3814. Drop a column family through debug cli tool

hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/debug/DropTable.java

@@ -0,0 +1,74 @@
+/*
+ * 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.hadoop.ozone.debug;
+
+import org.rocksdb.ColumnFamilyDescriptor;
+import org.rocksdb.ColumnFamilyHandle;
+import org.rocksdb.Options;
+import org.rocksdb.RocksDB;
+import picocli.CommandLine;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.Callable;
+
+/**
+ * Drop a column Family/Table in db.
+ */
+@CommandLine.Command(
+        name = "drop_column_family",
+        aliases = "drop",
+        description = "drop column family in db."
+)
+public class DropTable implements Callable<Void> {
+
+  @CommandLine.ParentCommand
+  private RDBParser parent;
+
+  @CommandLine.Option(names = {"-n", "--name"},
+      description = "column family name.")
+  private String name;
+
+  @Override
+  public Void call() throws Exception {
+    List<ColumnFamilyDescriptor> cfs = new ArrayList<>();
+    final List<ColumnFamilyHandle> columnFamilyHandleList =
+        new ArrayList<>();
+    List<byte[]> cfList = RocksDB.listColumnFamilies(new Options(),
+        parent.getDbPath());
+    byte[] nameByte = name.getBytes(StandardCharsets.UTF_8);
+    int deleteIndex = -1;
+    if (cfList != null) {
+      for (byte[] b : cfList) {
+        cfs.add(new ColumnFamilyDescriptor(b));
+        if (Arrays.equals(b, nameByte)) {
+          deleteIndex = cfs.size() - 1;
+        }
+      }
+    }
+    try (RocksDB rocksDB = RocksDB.open(
+        parent.getDbPath(), cfs, columnFamilyHandleList)) {
+      rocksDB.dropColumnFamily(
+          columnFamilyHandleList.get(deleteIndex));
+    }
+    return null;
+  }
+}

hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/debug/RDBParser.java

@@ -29,7 +29,8 @@
         description = "Parse rocksdb file content",
         subcommands = {
                 DBScanner.class,
-                ListTables.class
+                ListTables.class,
+                DropTable.class
         })
 public class RDBParser extends GenericCli {