Vidhya, Did you try setting scanner time range. It takes min and max timestamps, and when instantiating the scanner at RS, a time based filtering is done to include only selected store files. Have a look at StoreFile.shouldseek(Scan, Sortedset<byte[]). I think it should improve the response time.
Himanshu On Wed, Apr 13, 2011 at 8:44 AM, Vidhyashankar Venkataraman < [email protected]> wrote: > Hi > We had enabled scanner caching but I don't think it is the same issue > because scanner.next in this case is blocking: the scanner is busy in the > region server but hasn't returned anything yet since a row to be returned > hasn't been found yet (all rows have expired but are still there since they > havent been compacted yet). > > Vidhya > > On 4/13/11 1:44 AM, "Ted Yu" <[email protected]> wrote: > > Have you read the following thread ? > "ScannerTimeoutException when a scan enables caching, no exception when it > doesn't"Did you enable caching ? If not, it is different issue. > > On Wed, Apr 13, 2011 at 12:40 AM, Vidhyashankar Venkataraman < > [email protected]> wrote: > > > (This could be a known issue. Please let me know if it is). > > > > We had a set of uncompacted store files in a region. One of the column > > families had a store file of 5 Gigs. The other column families were > pretty > > small (a few megabytes at most). > > > > It so turned out that all these files had rows whose TTL had expired. > Now > > when this region was scanned (which should yield a result of a null set), > we > > got Scanner timeouts and UnknownScannerExceptions. > > > > And when we tried scanning the region without the large column family, > the > > scanner returned back safely with no result. > > > > So, I major compacted it and the scan started working correctly. > > > > So it looks like timeouts happen if the scanner does not return any > output > > for a specified time. > > Which isn't exactly the correct thing to do, because it could be the case > > that the scanner was indeed busy but it just so happened that there are > no > > rows yet to return back to the client. > > > > We can try increasing the scanner timeout, but this doesn't resolve the > > underlying problem. Is this a know issue? > > > > Thank you > > Vidhya > > > >
