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
