Question: Configuration (hortonworks)

* hive: BUILD hive-1.2.1.2.3.0.0
* Hadoop 2.7.1.2.3.0.0-2557

I'm trying to execute 

```
lock table event_metadata EXCLUSIVE;

```

Hive response:

> 
> Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. Current transaction manager does not support explicit lock requests. Transaction manager: org.apache.hadoop.hive.ql.lockmgr.DbTxnManager
> 
> 
> 

In the code there is obvious place where explicit locks are disabled:
<http://grepcode.com/file/repo1.maven.org/maven2/org.apache.hive/hive-exec/1.2.0/org/apache/hadoop/hive/ql/lockmgr/DbTxnManager.java#DbTxnManager>

```
321  @Override
322  public boolean supportsExplicitLock() {
323    return false;
324  }

```

Questions:

how can I make explicit locks work? In what version of hive do they appear?

Here is an example <http://www.ericlin.me/how-table-locking-works-in-hive> for cloudera that explicit locks work.

Answer: 
You may set the concurrency parameter on the fly:

```
 set hive.support.concurrency=true;

```

After this you may try executing your command
Try the following:

set hive.txn.manager=org.apache.hadoop.hive.ql.lockmgr.DummyTxnManager;

unlock table *tablename*;