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From Josh Elser <>
Subject Re: Trigger for Accumulo table
Date Thu, 03 Dec 2015 03:50:41 GMT
Hi Thai,

There is no out-of-the-box feature provided with Accumulo that does what 
you're asking for. Accumulo doesn't provide any functionality to push 
notifications to other systems. You could potentially maintain other 
tables/columns in which you maintain the last time a row was updated, 
but the onus is on your "other services" to read the table to find out 
when a change occurred (which is probably not scalable at "real time").

There are other systems you could likely leverage to solve this, 
depending on the durability and scalability that your application needs.

For a system "close" to Accumulo, you could take a look at Fluo [1] 
which is an implementation of Google's "Percolator" system. This is a 
system based on throughput rather than low-latency, so it may not be a 
good fit for your needs. There are probably other systems in the Apache 
ecosystem (Kafka, Storm, Flink or Spark Streaming maybe?) that are be 
helpful to your problem. I'm not an expert on these to recommend on (nor 
do I think I understand your entire architecture well enough).

Thai Ngo wrote:
> Hi list,
> I have a use-case when existing rows in a table will be updated by an
> internal service. Data in a row of this table is composed of 2 parts:
> 1st part - immutable and the 2nd one - will be updated (filled in) a
> little later.
> Currently, I have a need of knowing when and which rows will be updated
> in the table so that other services will be wisely start consuming the
> data. It will make more sense when I need to consume the data in near
> realtime. So developing a notification function or simpler - a trigger
> is what I really want to do now.
> I am curious to know if someone has done similar job or there are
> features or APIs or best practices available for Accumulo so far. I'm
> thinking of letting the internal service which updates the data notify
> us whenever it updates the data.
> What do you think?
> Thanks,
> Thai

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