Interesting!! Can't wait to see this in action. I am already imagining huge performance gains Regards, Dhaval
________________________________ From: Ted Yu <yuzhih...@gmail.com> To: "user@hbase.apache.org" <user@hbase.apache.org>; Dhaval Shah <prince_mithi...@yahoo.co.in> Sent: Thursday, 24 October 2013 1:06 PM Subject: Re: Add Columnsize Filter for Scan Operation For streaming responses, there is this JIRA: HBASE-8691 High-Throughput Streaming Scan API On Thu, Oct 24, 2013 at 9:53 AM, Dhaval Shah <prince_mithi...@yahoo.co.in>wrote: > Jean, if we don't add setBatch to the scan, MR job does cause HBase to > crash due to OOME. We have run into this in the past as well. Basically the > problem is - Say I have a region server with 12GB of RAM and a row of size > 20GB (an extreme example, in practice, HBase runs out of memory way before > 20GB). If I query the entire row, HBase does not have enough memory to > hold/process it for the response. > > In practice, if your setCaching > 1, then the aggregate of all rows > growing too big can also cause the same issue. > > I think 1 way we can solve this issue is making the HBase server serve > responses in a streaming fashion somehow (not exactly sure about the > details on how this can work but if it has to hold the entire row in > memory, its going to be bound by HBase heap size) > > Regards, > Dhaval > > > ________________________________ > From: Jean-Marc Spaggiari <jean-m...@spaggiari.org> > To: user <user@hbase.apache.org> > Sent: Thursday, 24 October 2013 12:37 PM > Subject: Re: Add Columnsize Filter for Scan Operation > > > If the MR crash because of the number of columns, then we have an issue > that we need to fix ;) Please open a JIRA provide details if you are facing > that. > > Thanks, > > JM > > > > 2013/10/24 John <johnnyenglish...@gmail.com> > > > @Jean-Marc: Sure, I can do that, but thats a little bit complicated > because > > the the rows has sometimes Millions of Columns and I have to handle them > > into different batches because otherwise hbase crashs. Maybe I will try > it > > later, but first I want to try the API version. It works okay so far, > but I > > want to improve it a little bit. > > > > @Ted: I try to modify it, but I have no idea how exactly do this. I've to > > count the number of columns in that filter (that works obviously with the > > count field). But there is no Method that is caleld after iterating over > > all elements, so I can not return the Drop ReturnCode in the > filterKeyValue > > Method because I did'nt know when it was the last one. Any ideas? > > > > regards > > > > > > 2013/10/24 Ted Yu <yuzhih...@gmail.com> > > > > > Please take a look > > > at > > src/main/java/org/apache/hadoop/hbase/filter/ColumnCountGetFilter.java : > > > > > > * Simple filter that returns first N columns on row only. > > > > > > You can modify the filter to suit your needs. > > > > > > Cheers > > > > > > > > > On Thu, Oct 24, 2013 at 7:52 AM, John <johnnyenglish...@gmail.com> > > wrote: > > > > > > > Hi, > > > > > > > > I'm write currently a HBase Java programm which iterates over every > row > > > in > > > > a table. I have to modiy some rows if the column size (the amount of > > > > columns in this row) is bigger than 25000. > > > > > > > > Here is my sourcode: http://pastebin.com/njqG6ry6 > > > > > > > > Is there any way to add a Filter to the scan Operation and load only > > rows > > > > where the size is bigger than 25k? > > > > > > > > Currently I check the size at the client, but therefore I have to > load > > > > every row to the client site. It would be better if the wrong rows > > > already > > > > filtered at the "server" site. > > > > > > > > thanks > > > > > > > > John > > > > > > > > > >
