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From Karthik Kambatla <kkamb...@cs.purdue.edu>
Subject Re: Flaky tableExists()
Date Wed, 21 Jul 2010 19:19:28 GMT
I  have tried 0.20.4 and it behaves the same way. Finally, I am back to
0.20.1, and it works fine.

Thanks
Karthik

On Wed, Jul 21, 2010 at 10:43 AM, Karthik Kambatla
<kkambatl@cs.purdue.edu>wrote:

> Thanks a lot for the prompt help. [I had sent an immediate reply but from
> the wrong address... hopefully, you would receive this.]
>
>
> I am running HBase 0.20.5. I have cleaned the whole cluster and re-setup
> everything (HDFS, MapReduce, and HBase). Here is the transcript -- from when
> the HBase cluster has been started.
>
>
> [kambatla@mercado-2 ~]$ hbase shell
> HBase Shell; enter 'help<RETURN>' for list of supported commands.
> Version: 0.20.5, rUnknown, Thu Jul 15 22:27:05 PDT 2010
>
> hbase(main):001:0> list
> 0 row(s) in 0.0910 seconds
>
> hbase(main):002:0> create 'Test'
> 0 row(s) in 1.0990 seconds
>
> hbase(main):003:0> list
> Test
>
>
> 1 row(s) in 0.0070 seconds
>
> hbase(main):004:0> exit
>
>
> [kambatla@mercado-2 ~]$ hbase shell
> HBase Shell; enter 'help<RETURN>' for list of supported commands.
> Version: 0.20.5, rUnknown, Thu Jul 15 22:27:05 PDT 2010
>
> hbase(main):001:0> list
> 0 row(s) in 0.0860 seconds
>
> hbase(main):004:0> scan '.META.'
> ROW
> COLUMN+CELL
>
>  Test,,1279665697803         column=info:server, timestamp=1279668781099,
> value=15.25.119.96:60020
>  Test,,1279665697803         column=info:serverstartcode,
> timestamp=1279668781099, value=1279665651801
> 1 row(s) in 0.0260 seconds
>
> hbase(main):005:0> create 'Test1'
> 0 row(s) in 1.1050 seconds
>
> hbase(main):006:0> list
> 0 row(s) in 0.0060 seconds
>
> hbase(main):007:0> scan '.META.'
> ROW
> COLUMN+CELL
>
>  Test,,1279665697803         column=info:server, timestamp=1279668781099,
> value=15.25.119.96:60020
>  Test,,1279665697803         column=info:serverstartcode,
> timestamp=1279668781099, value=1279665651801
> 1 row(s) in 0.0100 seconds
>
> hbase(main):008:0> exit
>
>
> [kambatla@mercado-2 ~]$ hbase shell
> HBase Shell; enter 'help<RETURN>' for list of supported commands.
> Version: 0.20.5, rUnknown, Thu Jul 15 22:27:05 PDT 2010
>
> hbase(main):001:0> list
> 0 row(s) in 0.0900 seconds
>
> hbase(main):002:0> scan '.META.'
> ROW
> COLUMN+CELL
>
> 0 row(s) in 0.0130 seconds
>
> hbase(main):003:0> scan '.META.'
> ROW
> COLUMN+CELL
>
> 0 row(s) in 0.0070 seconds
>
> Thanks
> Karthik
>
>
> On Tue, Jul 20, 2010 at 4:15 PM, Jonathan Gray <jgray@facebook.com> wrote:
>
>> Also, I'm not sure this will be fixed with the master changes.
>>
>> tableExists() actually makes a call to listTables() and then checks if the
>> table you are looking for is in the list.
>>
>> listTables() uses a MetaScanner/MetaVisitor.  Though the master changes
>> de-emphasize the general use of meta scanning, it would not necessarily
>> change the implementation of these client (to RS) calls.
>>
>> Hard to say what would make this flakey besides some of the older bugs
>> around lots of META StoreFiles.
>>
>> What version of HBase are you running?
>>
>> JG
>>
>> > -----Original Message-----
>> > From: Jonathan Gray [mailto:jgray@facebook.com]
>> > Sent: Tuesday, July 20, 2010 4:06 PM
>> > To: user@hbase.apache.org
>> > Subject: RE: Flaky tableExists()
>> >
>> > I've personally never seen a flaky tableExists() but it's not something
>> > I've used heavily.
>> >
>> > Could you do the same operations you did below in the shell but also
>> > run:  scan '.META.'
>> >
>> > > -----Original Message-----
>> > > From: Karthik Kambatla [mailto:karthik.shashank.kambatla@gmail.com]
>> > > Sent: Tuesday, July 20, 2010 3:26 PM
>> > > To: user@hbase.apache.org
>> > > Subject: Re: Flaky tableExists()
>> > >
>> > > Thanks Ryan for understanding the pain :)
>> > >
>> > > Is there a work-around for the time being? I haven't experienced any
>> > > such
>> > > issues with earlier versions of HBase. Was I just lucky or would it
>> > > make
>> > > sense to revert to earlier questions?
>> > >
>> > > Thanks
>> > > Karthik
>> > >
>> > > On Tue, Jul 20, 2010 at 2:54 PM, Ryan Rawson <ryanobjc@gmail.com>
>> > > wrote:
>> > >
>> > > > This sucks, and there are being substantial reworks to master
>> > > > functions in 0.90 :-)
>> > > >
>> > > > Hopefully that will permanently address these kinds of bugs.
>> > > >
>> > > > Hopefully within a few weeks there'll be a developer preview (0.89
>> > > > series) that has that code.
>> > > >
>> > > > -ryan
>> > > >
>> > > > On Tue, Jul 20, 2010 at 2:52 PM, Karthik Kambatla
>> > > > <kkambatl@cs.purdue.edu> wrote:
>> > > > > Hi all
>> > > > >
>> > > > > I have been noticing a slightly flaky behavior with respect to
>> > > > > HBaseAdmin.tableExists(). After I have created the table, it
>> > > returns
>> > > > > true/false every time when called. In hbase shell, the list
>> > command
>> > > > prints
>> > > > > out all the tables sometimes, and shows no tables on other
>> > > occasions. Any
>> > > > > ideas as to why this happens?
>> > > > >
>> > > > > The master on my cluster runs the HDFS - namenode, secondary
>> > > namenode;
>> > > > HBase
>> > > > > - HMaster, HQuorumPeer. The 12 slaves run the HDFS datanode and
>> > > HBase
>> > > > > HRegionServer. Below is the transcript of operations on hbase
>> > > shell...
>> > > > Every
>> > > > > time I exit and enter hbase shell, the output changes.
>> > > > >
>> > > > > Thanks
>> > > > > Karthik
>> > > > >
>> > > > > hbase(main):002:0> count 'SUBSCRIPTIONS'
>> > > > > 0 row(s) in 6.0560 seconds
>> > > > > hbase(main):003:0> create 'Test'
>> > > > > 0 row(s) in 1.0840 seconds
>> > > > > hbase(main):004:0> list
>> > > > > SUBSCRIPTIONS
>> > > > >
>> > > > >
>> > > > > 1 row(s) in 0.0090 seconds
>> > > > >
>> > > > > hbase(main):010:0> create 'Test'
>> > > > > NativeException: org.apache.hadoop.hbase.TableExistsException:
>> > > > > org.apache.hadoop.hbase.TableExistsException: Test
>> > > > >    at
>> > > >
>> > org.apache.hadoop.hbase.master.HMaster.createTable(HMaster.java:798)
>> > > > >    at
>> > > >
>> > org.apache.hadoop.hbase.master.HMaster.createTable(HMaster.java:762)
>> > > > >    at sun.reflect.GeneratedMethodAccessor13.invoke(Unknown
>> > Source)
>> > > > >    at
>> > > > >
>> > > >
>> > >
>> > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccesso
>> > > rImpl.java:25)
>> > > > >    at java.lang.reflect.Method.invoke(Method.java:597)
>> > > > >    at
>> > > org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:657)
>> > > > >    at
>> > > > >
>> > >
>> > org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:91
>> > > 5)
>> > > > >
>> > > > >
>> > > > > hbase(main):011:0> list
>> > > > > SUBSCRIPTIONS
>> > > > >
>> > > > > 1 row(s) in 0.0070 seconds
>> > > > > hbase(main):012:0> exit
>> > > > >
>> > > > > [kambatla@mercado-2 ~]$ hbase shell
>> > > > > HBase Shell; enter 'help<RETURN>' for list of supported
commands.
>> > > > > Version: 0.20.5, rUnknown, Thu Jul 15 22:27:05 PDT 2010
>> > > > > hbase(main):001:0> list
>> > > > > TOPICS
>> > > > >
>> > > > > Test
>> > > > >
>> > > > > TestTable
>> > > > >
>> > > > > USERS
>> > > > >
>> > > > > 4 row(s) in 0.0930 seconds
>> > > > > hbase(main):005:0> exit
>> > > > >
>> > > > > [kambatla@mercado-2 ~]$ hbase shell
>> > > > > HBase Shell; enter 'help<RETURN>' for list of supported
commands.
>> > > > > Version: 0.20.5, rUnknown, Thu Jul 15 22:27:05 PDT 2010
>> > > > > hbase(main):001:0> list
>> > > > > EVENTS
>> > > > >
>> > > > > SUBSCRIPTIONS
>> > > > >
>> > > > > TOPICS
>> > > > >
>> > > > > TestTable
>> > > > >
>> > > > > USERS
>> > > > >
>> > > > > 5 row(s) in 0.1000 seconds
>> > > > >
>> > > >
>>
>
>

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