diff --git a/bin/hbase b/bin/hbase
index 78dbbddc65e..18f58c90df2 100755
--- a/bin/hbase
+++ b/bin/hbase
@@ -106,6 +106,7 @@ if [ $# = 0 ]; then
echo " regionsplitter Run RegionSplitter tool"
echo " rowcounter Run RowCounter tool"
echo " cellcounter Run CellCounter tool"
+ echo " pre-upgrade Run Pre-Upgrade validator tool"
echo " CLASSNAME Run the class named CLASSNAME"
exit 1
fi
@@ -465,6 +466,8 @@ elif [ "$COMMAND" = "rowcounter" ] ; then
CLASS='org.apache.hadoop.hbase.mapreduce.RowCounter'
elif [ "$COMMAND" = "cellcounter" ] ; then
CLASS='org.apache.hadoop.hbase.mapreduce.CellCounter'
+elif [ "$COMMAND" = "pre-upgrade" ] ; then
+ CLASS='org.apache.hadoop.hbase.tool.PreUpgradeValidator'
else
CLASS=$COMMAND
fi
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/PreUpgradeValidator.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/PreUpgradeValidator.java
new file mode 100644
index 00000000000..138af6a3f75
--- /dev/null
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/PreUpgradeValidator.java
@@ -0,0 +1,129 @@
+/**
+ *
+ * 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.hbase.tool;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.hadoop.hbase.HBaseInterfaceAudience;
+import org.apache.hadoop.hbase.client.Admin;
+import org.apache.hadoop.hbase.client.ColumnFamilyDescriptor;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.ConnectionFactory;
+import org.apache.hadoop.hbase.client.TableDescriptor;
+import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
+import org.apache.hadoop.hbase.util.AbstractHBaseTool;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hbase.thirdparty.org.apache.commons.cli.CommandLine;
+
+/**
+ * Tool for validating that cluster can be upgraded from HBase 1.x to 2.0
+ *
+ * Available validations:
+ *
+ * - all: Run all pre-upgrade validations
+ * - validateDBE: Check Data Block Encoding for column families
+ *
+ *
+ */
+@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
+public class PreUpgradeValidator extends AbstractHBaseTool {
+
+ public static final String NAME = "pre-upgrade";
+ private static final Logger LOG = LoggerFactory.getLogger(PreUpgradeValidator.class);
+ private static final byte[] DATA_BLOCK_ENCODING = Bytes.toBytes("DATA_BLOCK_ENCODING");
+ private boolean validateAll;
+ private boolean validateDBE;
+
+ /**
+ * Check DataBlockEncodings for column families.
+ *
+ * @return DataBlockEncoding compatible with HBase 2
+ * @throws IOException if a remote or network exception occurs
+ */
+ private boolean validateDBE() throws IOException {
+ int incompatibilities = 0;
+
+ LOG.info("Validating Data Block Encodings");
+
+ try (Connection connection = ConnectionFactory.createConnection(getConf());
+ Admin admin = connection.getAdmin()) {
+ List tableDescriptors = admin.listTableDescriptors();
+ String encoding = "";
+
+ for (TableDescriptor td : tableDescriptors) {
+ ColumnFamilyDescriptor[] columnFamilies = td.getColumnFamilies();
+ for (ColumnFamilyDescriptor cfd : columnFamilies) {
+ try {
+ encoding = Bytes.toString(cfd.getValue(DATA_BLOCK_ENCODING));
+ // IllegalArgumentException will be thrown if encoding is incompatible with 2.0
+ DataBlockEncoding.valueOf(encoding);
+ } catch (IllegalArgumentException e) {
+ incompatibilities++;
+ LOG.warn("Incompatible DataBlockEncoding for table: {}, cf: {}, encoding: {}",
+ td.getTableName().getNameAsString(), cfd.getNameAsString(), encoding);
+ }
+ }
+ }
+ }
+
+ if (incompatibilities > 0) {
+ LOG.warn("There are {} column families with incompatible Data Block Encodings. Do not "
+ + "upgrade until these encodings are converted to a supported one.", incompatibilities);
+ LOG.warn("Check http://hbase.apache.org/book.html#upgrade2.0.prefix-tree.removed "
+ + "for instructions.");
+ return false;
+ } else {
+ LOG.info("The used Data Block Encodings are compatible with HBase 2.0.");
+ return true;
+ }
+ }
+
+ @Override
+ protected void addOptions() {
+ addOptNoArg("all", "Run all pre-upgrade validations");
+ addOptNoArg("validateDBE", "Validate DataBlockEncoding are compatible on the cluster");
+ }
+
+ @Override
+ protected void processOptions(CommandLine cmd) {
+ validateAll = cmd.hasOption("all");
+ validateDBE = cmd.hasOption("validateDBE");
+ }
+
+ @Override
+ protected int doWork() throws Exception {
+ boolean validationFailed = false;
+ if (validateDBE || validateAll) {
+ if (validateDBE()) {
+ validationFailed = true;
+ }
+ }
+
+ return validationFailed ? 1 : 0;
+ }
+
+ public static void main(String[] args) {
+ new PreUpgradeValidator().doStaticMain(args);
+ }
+}
diff --git a/src/main/asciidoc/_chapters/appendix_hfile_format.adoc b/src/main/asciidoc/_chapters/appendix_hfile_format.adoc
index 18eafe6a221..ba824999629 100644
--- a/src/main/asciidoc/_chapters/appendix_hfile_format.adoc
+++ b/src/main/asciidoc/_chapters/appendix_hfile_format.adoc
@@ -321,7 +321,7 @@ Version 3 added two additional pieces of information to the reserved keys in the
When reading a Version 3 HFile the presence of `MAX_TAGS_LEN` is used to determine how to deserialize the cells within a data block.
Therefore, consumers must read the file's info block prior to reading any data blocks.
-When writing a Version 3 HFile, HBase will always include `MAX_TAGS_LEN ` when flushing the memstore to underlying filesystem and when using prefix tree encoding for data blocks, as described in <>.
+When writing a Version 3 HFile, HBase will always include `MAX_TAGS_LEN` when flushing the memstore to underlying filesystem.
When compacting extant files, the default writer will omit `MAX_TAGS_LEN` if all of the files selected do not themselves contain any cells with tags.
diff --git a/src/main/asciidoc/_chapters/compression.adoc b/src/main/asciidoc/_chapters/compression.adoc
index 8fc1c559ca0..6fe0d769fe9 100644
--- a/src/main/asciidoc/_chapters/compression.adoc
+++ b/src/main/asciidoc/_chapters/compression.adoc
@@ -125,7 +125,7 @@ The compression or codec type to use depends on the characteristics of your data
In general, you need to weigh your options between smaller size and faster compression/decompression. Following are some general guidelines, expanded from a discussion at link:http://search-hadoop.com/m/lL12B1PFVhp1[Documenting Guidance on compression and codecs].
* If you have long keys (compared to the values) or many columns, use a prefix encoder.
- FAST_DIFF is recommended, as more testing is needed for Prefix Tree encoding.
+ FAST_DIFF is recommended.
* If the values are large (and not precompressed, such as images), use a data block compressor.
* Use GZIP for [firstterm]_cold data_, which is accessed infrequently.
GZIP compression uses more CPU resources than Snappy or LZO, but provides a higher compression ratio.
diff --git a/src/main/asciidoc/_chapters/ops_mgt.adoc b/src/main/asciidoc/_chapters/ops_mgt.adoc
index e364a0668d5..5a9ca8804eb 100644
--- a/src/main/asciidoc/_chapters/ops_mgt.adoc
+++ b/src/main/asciidoc/_chapters/ops_mgt.adoc
@@ -793,6 +793,28 @@ For general usage instructions, pass the `-h` option.
The LoadTestTool has received many updates in recent HBase releases, including support for namespaces, support for tags, cell-level ACLS and visibility labels, testing security-related features, ability to specify the number of regions per server, tests for multi-get RPC calls, and tests relating to replication.
+[[ops.pre-upgrade]]
+=== Pre-Upgrade validator
+Pre-Upgrade validator tool can be used to check the cluster for known incompatibilities before upgrading from HBase 1 to HBase 2.
+To run all the checks use the `-all` flag.
+
+[source, bash]
+----
+$ bin/hbase pre-upgrade -all
+----
+
+==== DataBlockEncoding validation
+HBase 2.0 removed `PREFIX_TREE` Data Block Encoding from column families.
+To verify that none of the column families are using incompatible Data Block Encodings in the cluster run the following command.
+
+[source, bash]
+----
+$ bin/hbase pre-upgrade -validateDBE
+----
+
+This check validates all column families and print out any incompatibilities.
+To change `PREFIX_TREE` encoding to supported one check <>.
+
[[ops.regionmgt]]
== Region Management