HBASE-29691: Change TableName.META_TABLE_NAME from being a global static by Kota-SH · Pull Request #7730 · apache/hbase

Kota-SH · 2026-02-10T15:35:58Z

HBASE-29691: Change TableName.META_TABLE_NAME from being a global static

Change TableName.META_TABLE_NAME from a global static constant to a dynamically discovered value from ConnectionRegistry.

Please refer to earlier discussion on the PR #7558 for further details.

Key changes:

Add ConnectionRegistry.getMetaTableName() method for dynamic discovery
Add MetaTableNameStore for persisting meta table name in master region
Update TableName to support dynamic meta table name
Update HMaster to integrate with MetaTableNameStore
Update all client and server code to use dynamic meta table name
Add protobuf changes for meta table name in Registry.proto

Refactoring for the test classes to be handled separately.

Change TableName.META_TABLE_NAME from a global static constant to a dynamically discovered value from ConnectionRegistry. Key changes: - Add ConnectionRegistry.getMetaTableName() method for dynamic discovery - Add MetaTableNameStore for persisting meta table name in master region - Update TableName to support dynamic meta table name - Update HMaster to integrate with MetaTableNameStore - Update all client and server code to use dynamic meta table name - Add protobuf changes for meta table name in Registry.proto Refactoring for the test classes to be handled separately.

anmolnar

lgtm. What are the build failures?

kgeisz

LGTM overall. I have some nit comments below. Also, I see PR #7558 is still open. Should that PR be closed?

kgeisz · 2026-02-10T22:06:32Z

hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfoBuilder.java

  // TODO: How come Meta regions still do not have encoded region names? Fix.
  // hbase:meta,,1.1588230740 should be the hbase:meta first region name.
+  // TODO: For now, hardcode to default. Future: lazy initialization based on config or make it use
+  // conenction


nit:

Suggested change

// conenction

// connection

kgeisz · 2026-02-10T23:52:47Z

hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparatorImpl.java

@@ -787,8 +787,13 @@ public static CellComparator getCellComparator(TableName tableName) {
   */
  public static CellComparator getCellComparator(byte[] tableName) {
    // FYI, TableName.toBytes does not create an array; just returns existing array pointer.


nit: Is this comment still applicable?

kgeisz · 2026-02-10T23:59:09Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/janitor/MetaFixer.java

    if (!createMetaEntriesFailures.isEmpty()) {
      LOG.warn(
-        "Failed to create entries in hbase:meta for {}/{} RegionInfo descriptors. First"
+        "Failed to create entries in {}} for {}/{} RegionInfo descriptors. First"


nit

Suggested change

"Failed to create entries in {}} for {}/{} RegionInfo descriptors. First"

"Failed to create entries in {} for {}/{} RegionInfo descriptors. First"

kgeisz · 2026-02-11T00:16:19Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/ModifyTableProcedure.java

        if (!cfs.contains(family)) {
          throw new HBaseIOException(
-            "Delete of hbase:meta column family " + Bytes.toString(family));
+            "Delete of " + env.getMetaTableName() + " column family " + Bytes.toString(family));


nit: IMO this could be a little more clear

Suggested change

"Delete of " + env.getMetaTableName() + " column family " + Bytes.toString(family));

"Invalid deletion of " + env.getMetaTableName() + " column family: " + Bytes.toString(family));

kgeisz · 2026-02-11T00:41:34Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MetaTableNameStore.java

+        LOG.debug("Loaded meta table name from Master Local Region: {}", cachedMetaTableName);
+        return cachedMetaTableName;
+      }
+      LOG.info("No stored meta table name found in Master Local Region:  {}", cachedMetaTableName);


nit

Suggested change

LOG.info("No stored meta table name found in Master Local Region: {}", cachedMetaTableName);

LOG.info("No stored meta table name found in Master Local Region: {}", cachedMetaTableName);

kgeisz · 2026-02-11T00:45:25Z

hbase-server/src/main/java/org/apache/hadoop/hbase/tool/BulkLoadHFilesTool.java

        startEndKeys.get(idx + 1).getFirst()) == 0)
    ) {
      throw new IOException("The endkey of one region for table " + tableName
        + " is not equal to the startkey of the next region in hbase:meta."


kgeisz · 2026-02-11T00:50:01Z

hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java

+        LOG.warn(
+          "Unable to close region " + hi.getRegionNameAsString()
+            + " because {} had invalid or missing " + HConstants.CATALOG_FAMILY_STR + ":"
+            + Bytes.toString(HConstants.REGIONINFO_QUALIFIER) + " qualifier value.",
+          connection.getMetaTableName());


nit: I see a mixture of using string concatenation as well as {} in the LOG.warn() method. IMO is should consistently use the {} convention.

kgeisz · 2026-02-11T00:51:22Z

hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java

+        LOG.info("Patching {} with .regioninfo: " + hbi.getHdfsHRI(),
+          connection.getMetaTableName());


nit: Mixture of string concatenation and {} in log method

kgeisz · 2026-02-11T00:51:30Z

hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java

+        LOG.info("Patching {} with with .regioninfo: " + hbi.getHdfsHRI(),
+          connection.getMetaTableName());


nit: Mixture of string concatenation and {} in log method

kgeisz · 2026-02-11T00:53:07Z

hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java

-          + hbi.getMetaEntry().regionServer + " but is multiply assigned to region servers "
-          + Joiner.on(", ").join(hbi.getDeployedOn()));
+        "Region " + descriptiveName + " is listed in " + connection.getMetaTableName()
+          + " on region server " + hbi.getMetaEntry().regionServer + " but is multiply assigned"


nit: Do you have any idea what they mean by "multiply assigned"? Like "multi-assigned"?

Apache9 · 2026-02-23T15:25:30Z

Just came back from vacation...
This is a big change, please give me more time for reviewing...
Thanks.

Copilot

Pull request overview

This pull request implements HBASE-29691, which changes TableName.META_TABLE_NAME from a global static constant to a dynamically discovered value. The change enables support for cluster-specific meta table names, particularly for read replica clusters and other specialized configurations.

Changes:

Adds ConnectionRegistry.getMetaTableName() method for dynamic meta table name discovery
Introduces MetaTableNameStore class to persist the meta table name in the Master Local Region
Updates Connection, AsyncConnection, and MasterServices interfaces to expose getMetaTableName() method
Modifies TableName.isMetaTableName() to support both default "hbase:meta" and variant table names with suffixes
Updates all client and server code paths to use the dynamic meta table name instead of the static constant
Adds new RPC endpoint GetMetaTableName in Registry.proto for retrieving the meta table name from the master

Reviewed changes

Copilot reviewed 98 out of 98 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
hbase-protocol-shaded/src/main/protobuf/server/Registry.proto	Adds GetMetaTableName RPC request/response messages
hbase-server/src/main/java/org/apache/hadoop/hbase/master/MetaTableNameStore.java	New class to store/retrieve meta table name from Master Local Region
hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java	Integrates MetaTableNameStore and overrides getMetaTableName()
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java	Implements getMetaTableName() to fetch from master via connection
hbase-client/src/main/java/org/apache/hadoop/hbase/client/Connection.java	Adds getMetaTableName() and getMetaTable() helper methods
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncConnection.java	Adds getMetaTableName() and getMetaTable() helper methods
hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionRegistry.java	Adds getMetaTableName() method for discovering meta table name
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncConnectionImpl.java	Stores and exposes meta table name fetched from registry
hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionFactory.java	Fetches meta table name from registry during connection creation
hbase-common/src/main/java/org/apache/hadoop/hbase/TableName.java	Updates isMetaTableName() to support meta table name variants, deprecates META_TABLE_NAME
hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparatorImpl.java	Updates comparator selection to support dynamic meta table names
hbase-server/src/main/java/org/apache/hadoop/hbase/HBaseServerBase.java	Provides default getMetaTableName() implementation
hbase-server/src/main/java/org/apache/hadoop/hbase/HBaseRpcServicesBase.java	Implements getMetaTableName() RPC handler
Multiple server-side utilities	Updates HBaseFsck, RegionMover, MetaTableAccessor, and other utilities to use dynamic meta table name
Multiple test files	Updates test infrastructure and mocks to support dynamic meta table name

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Copilot · 2026-02-23T15:32:45Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

          LOG.info(
            "The {} config is {} while the replica count in TableDescriptor is {}"
              + " for hbase:meta, altering...",
-            HConstants.META_REPLICAS_NUM, replicasNumInConf, metaDesc.getRegionReplication());
+            HConstants.META_REPLICAS_NUM, replicasNumInConf, metaDesc.getRegionReplication(),
+            getMetaTableName());


The log format at line 1207 has incorrect parameter count. The format string has 3 placeholders ("The {} config is {} while the replica count in TableDescriptor is {} for hbase:meta, altering...") but 4 arguments are provided: HConstants.META_REPLICAS_NUM, replicasNumInConf, metaDesc.getRegionReplication(), and getMetaTableName(). This will cause a logging error. The fourth parameter getMetaTableName() should be part of the format string template, not an extra argument.

Copilot · 2026-02-23T15:32:46Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

+    } catch (IOException e) {
+      LOG.info("Exception loading/storing meta table name from master region");
+      throw new RuntimeException(e);
+    }


The error message at line 1689 is missing important context. When logging an exception, it should describe what operation failed. The message "Exception loading/storing meta table name from master region" should be logged with the exception using LOG.error() or LOG.warn() with the exception as the second parameter, not LOG.info(). Also, rethrowing as RuntimeException loses the original exception message - consider using new RuntimeException("Exception loading/storing meta table name from master region", e) to preserve the exception chain.

Copilot · 2026-02-23T15:32:46Z

hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparatorImpl.java

  }
+
+  static boolean isMetaTable(byte[] tableName) {
+    return Bytes.startsWith(tableName, TableName.META_TABLE_NAME.getName());


The implementation uses TableName.META_TABLE_NAME.getName() as a prefix check, but this could match unintended table names. For example, if someone creates a table "hbase:metadata", this check would incorrectly return true because it starts with "hbase:meta". The logic should verify exact match or use a more precise delimiter-based check. Consider checking if the bytes are exactly equal OR if they match the pattern with an underscore separator.

Suggested change

return Bytes.startsWith(tableName, TableName.META_TABLE_NAME.getName());

byte[] metaName = TableName.META_TABLE_NAME.getName();

// Match exactly "hbase:meta" or names starting with "hbase:meta_" (e.g., "hbase:meta_1").

if (Bytes.equals(tableName, metaName)) {

return true;

}

if (tableName == null || tableName.length <= metaName.length) {

return false;

}

if (!Bytes.startsWith(tableName, metaName)) {

return false;

}

// Require an underscore delimiter after "hbase:meta" to avoid matching names like "hbase:metadata".

return tableName[metaName.length] == (byte) '_';

Copilot · 2026-02-23T15:32:46Z

hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfoBuilder.java

  // TODO: How come Meta regions still do not have encoded region names? Fix.
  // hbase:meta,,1.1588230740 should be the hbase:meta first region name.
+  // TODO: For now, hardcode to default. Future: lazy initialization based on config or make it use
+  // conenction


The comment on line 46 has a typo: "conenction" should be "connection".

Suggested change

// conenction

// connection

Copilot · 2026-02-23T15:32:47Z

hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java

+  private static TableName getMetaTableNameFromConf(Configuration conf) {
+    // TODO: Support replica-specific meta table names from masterRegion
+    return TableName.META_TABLE_NAME;


The TODO comment on line 147 mentions "Support replica-specific meta table names from masterRegion" but this contradicts the PR's design. The PR adds MetaTableNameStore which stores the meta table name in the master region. This method, however, is static and doesn't have access to the master region. The comment and implementation should be aligned - either this method should not exist (and callers should use the dynamic meta table name from the connection/master), or the TODO should explain how static methods will interact with the dynamic meta table name system.

Copilot · 2026-02-23T15:32:47Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MetaTableNameStore.java

+      LOG.info("No stored meta table name found in Master Local Region:  {}", cachedMetaTableName);
+      return cachedMetaTableName;


The log message at line 89 is misleading. When no stored meta table name is found, cachedMetaTableName is still null, but the log message says "No stored meta table name found in Master Local Region: {}", cachedMetaTableName. This will log null, which is confusing. The message should be clearer that no value was found and null will be returned.

Copilot · 2026-02-23T15:32:48Z

hbase-server/src/main/java/org/apache/hadoop/hbase/master/janitor/MetaFixer.java

    if (!createMetaEntriesFailures.isEmpty()) {
      LOG.warn(
-        "Failed to create entries in hbase:meta for {}/{} RegionInfo descriptors. First"
+        "Failed to create entries in {}} for {}/{} RegionInfo descriptors. First"


The log parameter format string has a typo - there's an extra closing brace. The format string shows "Failed to create entries in {}} for {}/{}" but should be "Failed to create entries in {} for {}/{}" with only one closing brace after the first placeholder.

Copilot · 2026-02-23T15:32:48Z

hbase-common/src/main/java/org/apache/hadoop/hbase/TableName.java

+      throw new IllegalArgumentException(OLD_META_STR + " no longer exists. The table has been "
+        + "renamed to hbase:meta or hbase:meta_suffix in conf");


The error message at line 305-306 references "hbase:meta or hbase:meta_suffix in conf" but this is confusing because the meta table name is not directly configured. The message should be updated to reflect that the meta table name is dynamically discovered, not configured. Consider: "The table has been renamed to hbase:meta (or a cluster-specific meta table name)"

Copilot · 2026-02-23T15:32:48Z

hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/client/ThriftConnection.java

+  @Override
+  public TableName getMetaTableName() {
+    return toAsyncConnection().getMetaTableName();
+  }


Calling toAsyncConnection().getMetaTableName() on line 374 will throw NotImplementedException because toAsyncConnection() on line 379 throws NotImplementedException. This creates a method that always throws an exception, which is a bug. The getMetaTableName() implementation should either throw NotImplementedException directly or have a proper implementation that doesn't depend on toAsyncConnection().

Copilot · 2026-02-23T15:32:49Z

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

+  public TableName getMetaTableName() {
+    if (asyncClusterConnection != null) {
+      try {
+        return asyncClusterConnection.getMetaTableName();
+      } catch (Exception e) {
+        LOG.warn("Failed to get meta table name from Master", e);
+      }
+    }
+    // Bootstrap
+    return super.getMetaTableName();
+  }


The getMetaTableName() method in HRegionServer could return different values over time, which could cause inconsistencies. During bootstrap (before asyncClusterConnection is set), it returns the default meta table name from the parent class. After the connection is established, it returns the value from the connection. If there's any caching or state that depends on this value, changing it mid-execution could cause issues. Consider caching the value once it's successfully retrieved from the connection to ensure consistency.

anmolnar approved these changes Feb 10, 2026

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kgeisz suggested changes Feb 11, 2026

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Apache9 requested review from Apache9 and Copilot February 23, 2026 15:25

Copilot started reviewing on behalf of Apache9 February 23, 2026 15:26 View session

Copilot AI reviewed Feb 23, 2026

View reviewed changes

	"Failed to create entries in {}} for {}/{} RegionInfo descriptors. First"
	"Failed to create entries in {} for {}/{} RegionInfo descriptors. First"

	"Delete of " + env.getMetaTableName() + " column family " + Bytes.toString(family));
	"Invalid deletion of " + env.getMetaTableName() + " column family: " + Bytes.toString(family));

	LOG.info("No stored meta table name found in Master Local Region: {}", cachedMetaTableName);
	LOG.info("No stored meta table name found in Master Local Region: {}", cachedMetaTableName);

		LOG.info("Patching {} with .regioninfo: " + hbi.getHdfsHRI(),
		connection.getMetaTableName());

		LOG.info("Patching {} with with .regioninfo: " + hbi.getHdfsHRI(),
		connection.getMetaTableName());

-    return Bytes.startsWith(tableName, TableName.META_TABLE_NAME.getName());
+    byte[] metaName = TableName.META_TABLE_NAME.getName();
+    // Match exactly "hbase:meta" or names starting with "hbase:meta_" (e.g., "hbase:meta_1").
+    if (Bytes.equals(tableName, metaName)) {
+      return true;
+    }
+    if (tableName == null || tableName.length <= metaName.length) {
+      return false;
+    }
+    if (!Bytes.startsWith(tableName, metaName)) {
+      return false;
+    }
+    // Require an underscore delimiter after "hbase:meta" to avoid matching names like "hbase:metadata".
+    return tableName[metaName.length] == (byte) '_';

		LOG.info("No stored meta table name found in Master Local Region: {}", cachedMetaTableName);
		return cachedMetaTableName;

		throw new IllegalArgumentException(OLD_META_STR + " no longer exists. The table has been "
		+ "renamed to hbase:meta or hbase:meta_suffix in conf");

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Kota-SH commented Feb 10, 2026

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kgeisz Feb 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Apache9 commented Feb 23, 2026

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Pull request overview

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kgeisz Feb 11, 2026 •

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