Could you please post your code that is doing the scanning Steven?
On Thu, Apr 22, 2010 at 3:50 PM, Michael Segel <michael_se...@hotmail.com> wrote: > > Ok... > > This is something that I think we'll need input from a major contributor... > > It looks like there may be an issue with respect to row locking... > > I guess the questions to ask are: > > - How does HBase handle row level locking? > -Concurrent reads/fetches of the same row? > > To be honest and fair, HBase is still an immature product when compared to > databases and there going to be some issues that need to be fleshed out. > (Lets see where we are in 20+ years ;-) > > I wish I knew more about the internals of HBase, but there are only so many > hours in the day and my wife forces me to work so I can keep up with her > spending. ;-) (And if any of you happen to ever meet her, please don't bring > this up, she'll kill me. :-D ) > > Lets see what St.Ack or Andrew have to say. This might be a JIRA issue. > > Thx > > -Mike > > > >> Date: Thu, 22 Apr 2010 20:17:12 +0800 >> Subject: Re: multiple scanners on same table will cause problem? Scan >> results change among different tries. >> From: steven.zhuang.1...@gmail.com >> To: hbase-user@hadoop.apache.org >> >> hi, Michael, >> >> Sorry for not making the question clear, there are multiple >> scanners scanning a single table, there might be the case multiple scanners >> reading from a single region. >> please see answers inline. >> >> On Thu, Apr 22, 2010 at 8:08 PM, Michael Segel >> <michael_se...@hotmail.com>wrote: >> >> > >> > I'm sorry, but are you trying to say that you have multiple scanners trying >> > to read from a single region and the result sets do not match? >> > >> > Yes, the result sets do not match. >> >> > I guess it would be an easy test, enter a bunch of rows in to a region and >> > have a unique integer for each row. (1,2,3,...) >> > Then run a bunch of unfiltered scans in parallel, and generate a sum from >> > the scan. If any of the sums do not match, then you have a potential issue >> > on concurency/row locking, and row isolation level. How does HBase handle >> > row level locking and isolation levels? >> > >> > I have iterate on the rows/columnfamilies/cells, and printed the content of >> each cell, found that there are some cells missing in some scan result set. >> >> > -Mike >> > >> > > Date: Thu, 22 Apr 2010 17:07:47 +0800 >> > > Subject: multiple scanners on same table will cause problem? Scan results >> > change among different tries. >> > > From: steven.zhuang.1...@gmail.com >> > > To: hbase-user@hadoop.apache.org >> > > >> > > hi, All, >> > > Has anybody do scan on one table using multiple scanners at the >> > > same time and found some inconsistent problem? >> > > I am doing query on a table using dozens(20-120) of scanners in >> > > parallel(multiple threads), trying to take advantage of the multiple >> > cores. >> > > But I found the scan results doesn't consist among several goes. I have >> > > checked my code, seems there is no bug in it. So I guess the problem may >> > > come from the HBase itself. >> > > My HBase version is 0.20.3. >> > >> > _________________________________________________________________ >> > The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with >> > Hotmail. >> > >> > http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_5 >> > > > _________________________________________________________________ > Hotmail is redefining busy with tools for the New Busy. Get more from your > inbox. > http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_2
