Re: newbie help: error in dropping/recreating tables

Mon, 19 Oct 2009 10:16:12 -0700

Thanks again, yep I am going to switch to just creating one column family with 30 qualifiers. 

On Oct 19, 2009, at 10:38 AM, Jonathan Gray wrote:


There is a distinct difference between adding "columns" and adding  
"column families".



As you hinted at in a previous e-mail, you really wanted a single  
family with multiple qualifiers in it.



Creating a table, disabling it, modifying it (adding column  
_families_), enabling it, and repeating could certainly uncover some  
of the "issues" in those operations, this is what is meant by  
flaky.  It does mostly work, but in a scenario like that where you  
are rapidly altering and modifying the table state, it could uncover  
some of the flakiness :)



Cleaning up this process is one of the major targets for 0.21, at  
which point doing what you did originally (however misguided it may  
have been) would work without issue.


JG

yz5od2 wrote:

OK, changing the way I create tables to the suggested way below  
(populating a table descriptor prior to table create, VS. adding  
columns to a pre-existing table) appears to have fixed this issue.   
(Thanks!)
However i don't understand why adding columns to an existing table  
vs via the descriptor before table creation works vs. the latter  
does not.
Why would adding columns to an existing table, have such an effect  
on failing to re-create a table on the 2nd run? Might this be a bug?

On Oct 19, 2009, at 9:11 AM, Tatsuya Kawano wrote:

Hi,

Could you please set the logging level to DEBUG and check the hbase
master log and region server log if they have some error or warning

messages? By default, those logs should be under $HBASE_HOME/logs/  
and

you can set DEBUG logging by un-commenting the following line in
$HBASE_HOME/conf/log4j.properties

log4j.logger.org.apache.hadoop.hbase=DEBUG


Also, when you create a table, you can skip disabling and enabling

steps by adding HColumnDescriptor ***before*** creating the table.  
So

why don't you try this?

================================
HTableDescriptor tableDesc = new HTableDescriptor(tableName);

String[] columns = this.getColumns(clazz);

for (String column : columns) {
  tableDesc.addFamily(tableName, new HColumnDescriptor(column));
}

admin.createTable(tableDesc);
================================

Thanks,

--
Tatsuya Kawano (Mr.)
Tokyo, Japan




On Mon, Oct 19, 2009 at 9:53 AM, yz5od2 <[email protected] 
> wrote:

And another followup.


One of the table's has around 30 columns (MyTable1). If I do not  
create any
of the columns in this table on the 2nd run of the test, the  
table is

created, disabled, enabled, then dropped successfully.


Are there any restrictions in column names or anything related to  
inserting
data into that table, then dropping it that I would need to be  
aware of?


On Oct 18, 2009, at 11:48 AM, yz5od2 wrote:


Hi,
I am running the latest version of Hbase in standalone mode.


I have a Junit test which connects to the local Hbase process,  
creates 2
tables, inserts some records, reads those records, then deletes  
the records.
When the test is done, it disables both tables and then deletes  
the tables.
All of these actions complete successfully. When I bring up the  
Hbase shell,

I verify that the tables do not exist. (code below)

-----------------
1st run
-----------------

Here is the console output when it creates the new tables before  
inserting

data


[18/10/09 11:35:57:057 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1
[18/10/09 11:35:57:057 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1

[18/10/09 11:35:58:058 MDT]  INFO client.HBaseAdmin: Enabled table
MyTable1
[18/10/09 11:35:58:058 MDT]  INFO client.HBaseAdmin: Enabled table
MyTable1

[18/10/09 11:36:10:010 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable2
[18/10/09 11:36:10:010 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable2

[18/10/09 11:36:10:010 MDT]  INFO client.HBaseAdmin: Enabled table
MyTable2
[18/10/09 11:36:10:010 MDT]  INFO client.HBaseAdmin: Enabled table
MyTable2

DATA IS PUT, GET and DELETEd here.....


[18/10/09 11:37:27:027 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1
[18/10/09 11:37:27:027 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1
[18/10/09 11:37:27:027 MDT]  INFO client.HBaseAdmin: Deleted  
MyTable1
[18/10/09 11:37:27:027 MDT]  INFO client.HBaseAdmin: Deleted  
MyTable1
[18/10/09 11:37:33:033 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable2
[18/10/09 11:37:33:033 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable2
[18/10/09 11:37:33:033 MDT]  INFO client.HBaseAdmin: Deleted  
MyTable2
[18/10/09 11:37:33:033 MDT]  INFO client.HBaseAdmin: Deleted  
MyTable2



After the process completes, I verify in Hbase shell that the  
tables in

fact do not exist.


-------------------
2nd run
-------------------


However when I run the same test the 2nd time, it fails on  
trying to

enable the first table it re-creates, with the following error.


[18/10/09 11:39:42:042 MDT]  INFO zookeeper.ClientCnxn: Server  
connection

successful

[18/10/09 11:39:55:055 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1
[18/10/09 11:39:55:055 MDT]  INFO client.HBaseAdmin: Disabled  
MyTable1



At this point it seems to sit there, and fails with the  
following error.
When I go to Hbase shell, I see that the MyTable1 does in fact  
exist.
However it looks like my code fails on enabling it. What might  
be the

problem?


Caused by: java.io.IOException: Unable to enable table MyTable1
      at

org 
.apache 
.hadoop.hbase.client.HBaseAdmin.enableTable(HBaseAdmin.java:356)

      at

org 
.apache 
.hadoop.hbase.client.HBaseAdmin.enableTable(HBaseAdmin.java:315)




I really don't follow why this error is occurring. here is my  
code that

creates the tables and deletes them:


this.config = new HBaseConfiguration();
try {
      admin = new HBaseAdmin(config);
} catch(MasterNotRunningException e) {

      throw new Exception("Could not setup HBaseAdmin as no  
master is

running...");
}

// FOR EACH of my tables (MyTable1 and MyTable2)
...

String tableName = clazz.getSimpleName();

if (!admin.tableExists(tableName)) {
      admin.createTable(new HTableDescriptor(tableName));
      admin.disableTable(tableName);

      String[] columns = this.getColumns(clazz);

      for (String column : columns) {

              admin.addColumn(tableName, new  
HColumnDescriptor(column));

      }

}

if (!admin.isTableEnabled(tableName)) {
      admin.enableTable(tableName);
}

.....


// MY CODE TO DELETE THE TABLES (for each ... MyTable1 etc..)
if (admin.tableExists(tableName)) {
      admin.disableTable(tableName);
      admin.deleteTable(tableName);
}






























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