Why hive 0.13 will initialize derby database if the metastore parameters are not set in hive-site.xml?

[Jim Green]

Hi Team,

Starting from hive 0.13, if the metastore parameters are not set in
hive-site.xml, but we set in .hiverc, hive will try to initialize derby
database in current working directory.
This behavior did not exist in hive 0.12.
Is it a known bug? or behavior change?

I have the repro as below:

*Env:*
Hive 0.13
MySQL as backend metastore database.
No hive metastore service.

*Case 1:*
.hiverc is not used and hive-site.xml has below 4 parameters:
<property>
  <name>javax.jdo.option.ConnectionURL</name>
  <value>jdbc:mysql://localhost/metastore</value>
  <description>the URL of the MySQL database</description>
</property>

<property>
  <name>javax.jdo.option.ConnectionDriverName</name>
  <value>com.mysql.jdbc.Driver</value>
</property>

<property>
  <name>javax.jdo.option.ConnectionUserName</name>
  <value>hive</value>
</property>

<property>
  <name>javax.jdo.option.ConnectionPassword</name>
  <value>mypassword</value>
</property>

In this case, if we run "hive" and it works fine and connects to mysql as
the backend metastore database.
It will NOT initialize the derby database in current directory.

*Case 2:*
hive-site.xml is empty and .hiverc has below 3 parameters:
[root@~]# cat .hiverc
set javax.jdo.option.ConnectionURL=jdbc:mysql://localhost/metastore;
set javax.jdo.option.ConnectionDriverName=com.mysql.jdbc.Driver;
set javax.jdo.option.ConnectionUserName=hive;
set javax.jdo.option.ConnectionPassword=mypassword;

In this case, if we run "hive" and it also works fine and connects to mysql
as the backend metastore database.
However it initialized the derby database in current working directory
where you run "hive" command:

drwxr-xr-x   5 root root   4096 Mar  6 12:18 metastore_db
-rw-r--r--   1 root root  70754 Mar  6 12:18 derby.log

If we open another putty session and run "hive" in the same directory, it
will fail with below error:
"Caused by: ERROR XSDB6: Another instance of Derby may have already booted
the database /xxx/xxx/xxx/metastore_db."
This is because derby database only allows one connection.

We do not understand why after we moved the 4 parameters from hive-site.xml
to .hiverc, hive will try to initialize the derby database?


-- 
Thanks,
www.openkb.info
(Open KnowledgeBase for Hadoop/Database/OS/Network/Tool)