Thank you guys, @Mohammad : Yeah I should retreice all the rows and compare each of them to a specific value. As I understand that Hbase by default doesn't support parallel scan,but I can implement it by my own through Coprocessors & knowing the start/end row key on each region, am I correct ?
Farrokh On Fri, Feb 1, 2013 at 8:37 PM, James Taylor <[email protected]> wrote: > If you run a SQL query that does aggregation (i.e. uses a built-in > aggregation function like COUNT or does a GROUP BY), Phoenix will > orchestrate the running of a set of queries in parallel, segmented along > your row key (driven by the start/stop key plus region boundaries). We take > advantage of a nifty feature that Lars added where you can pass in your own > ExecutorService to an HTable, so you could do something similar. > > Regards, > > James > > > On 02/01/2013 08:40 AM, Mohammad Tariq wrote: > >> Do you need to scan each n every row within that range?Or you need >> specific >> rows based on some filter? >> >> Warm Regards, >> Tariq >> https://mtariq.jux.com/ >> cloudfront.blogspot.com >> >> >> On Fri, Feb 1, 2013 at 9:16 PM, lars hofhansl <[email protected]> wrote: >> >> The scan contract in HBase is that all rows are returned in order, so all >>> regions have to be traversed in order as well. >>> It would be nice to add some facility to HBase to performs the scanning >>> in >>> parallel. >>> >>> >>> >>> ______________________________**__ >>> From: Farrokh Shahriari <[email protected]**> >>> To: [email protected] >>> Sent: Friday, February 1, 2013 5:52 AM >>> Subject: Parallel scan in HBase >>> >>> Hi there >>> I have two question about scan in Hbase : >>> 1) Does scan operation with specific filter run in parallel on different >>> regionservers ? >>> 2) I wanna know whether this code runs at client side for searching the >>> retrieved results or not ? >>> >>> for (Result result : scanner1) { >>> for (KeyValue kv : result.raw()) { >>> // >>> // some coeds >>> // >>> } >>> } >>> >>> >>> Farrokh Shahriari >>> >>> >> >
