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HBase >> mail # user >> CheckAndAppend Feature


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Jerry Lam 2012-08-07, 15:22
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syed kather 2012-08-07, 16:09
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syed kather 2012-08-07, 16:12
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lars hofhansl 2012-08-07, 15:55
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Alex Baranau 2012-08-07, 16:00
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lars hofhansl 2012-08-08, 00:30
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Michael Segel 2012-08-08, 00:54
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lars hofhansl 2012-08-08, 01:05
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Re: CheckAndAppend Feature
Hi Lars,

To be honest its just an initial gut feel.
I haven't thought the issue through and I wonder if there are any downsides like dead locks or if some code goes awry how to recover.

I understand that its on the server side, and that's why I'm a little concerned.
On Aug 7, 2012, at 8:05 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:

> Hi Mike,
>
> do you have a specific downside in mind?The built-in checkAndSet type operations do the same.
> Coprocessors are an extension mechanism for HBase, not to be compared with (say) server side stored procedures in relational databases.
>
> (the canonical example is that nothing stops a RegionObserver implementation from calling System.exit(), taking the RegionServer with it).
>
>
> -- Lars
>
>
>
> ----- Original Message -----
> From: Michael Segel <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
> Cc:
> Sent: Tuesday, August 7, 2012 5:54 PM
> Subject: Re: CheckAndAppend Feature
>
> While this may be a trivial fix, have you considered possible down sides to the implementation?
>
> I'm not sure its a bad idea, but one that could have some potential issues when put into practice.
>
> -Mike
>
> On Aug 7, 2012, at 7:30 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
>> I filed HBASE-6522. It is a trivial change to make locks and leases available to coprocessors.
>> So checkAndSet type operations can then be implemented via coprocessor endpoints: lock row, check, fail or update, unlock row.
>>
>> Since the patch is so simple I'll commit that soon (to 0.94.2 and 0.96)
>>
>>
>> -- Lars
>>
>> ________________________________
>> From: lars hofhansl <[EMAIL PROTECTED]>
>> To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
>> Sent: Tuesday, August 7, 2012 8:55 AM
>> Subject: Re: CheckAndAppend Feature
>>
>> There is no such functionality currently, and there is no good way to simulate that.
>>
>> Currently that cannot even be done with a coprocessor endpoint, because region coprocessors have no way to create a region lock (just checked the code).
>> (That is something we have to change I think - I will create an issue once the Jira system is back from the walk in the park).
>>
>> -- Lars
>>
>>
>> ----- Original Message -----
>> From: Jerry Lam <[EMAIL PROTECTED]>
>> To: user <[EMAIL PROTECTED]>
>> Cc:
>> Sent: Tuesday, August 7, 2012 8:22 AM
>> Subject: CheckAndAppend Feature
>>
>> Hi HBase community:
>>
>> I checked the HTable API, it has checkAndPut and checkAndDelete but I'm
>> looking for checkAndAppend. Is there a way to simulate similarly?
>> For instance, I want to check the last 32 bytes of a value (let assume that
>> it has 128 bytes in total) in a column before appending atomically some
>> values into it.
>>
>> Thanks!
>>
>> Jerry
>>
>
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lars hofhansl 2012-08-08, 02:04
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Jerry Lam 2012-08-08, 00:50
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB