In our hbase cluster, I test if delete records with hlog or without. Attachment is my my test. The result of test can testify why I make a decision of delete rows without hlog .
2012/11/22 Bing Jiang <[email protected]> > Thanks for all your suggestion and talk. > One idea occurs to me why not check or restore wal when compaction > executes. If it does, hbase can drop some unused hlog, I think that will be > effective to the issue. > please correct me if I am wrong. > > ---Bing > > 2012/11/22 lars hofhansl <[email protected]> > >> I have it on my list of things to do to allow deferred WAL flush as a per >> operation option (right now it's a CF option). >> You really do not want to do anything with the WAL off. If you use >> deferred flush there is still a chance that this might happen (the RS could >> die in the few seconds after a Delete before it is flushed to the WAL), but >> it should be a rare occurrance. >> >> >> -- Lars >> >> >> >> ________________________________ >> From: Bing Jiang <[email protected]> >> To: [email protected] >> Sent: Wednesday, November 21, 2012 7:20 AM >> Subject: Re: delete rows without writing HLog may be appear in the future? >> >> we need to confirm that put must be safe,but deletes must be quick and >> low-latency. >> On Nov 21, 2012 11:10 PM, "Michael Segel" <[email protected]> >> wrote: >> >> > Some time later? >> > >> > Time of course is relative, so I have to ask what occurred between the >> > write and the delete? >> > How much time? Did you have any compactions in between the write and the >> > delete? >> > >> > Why are you not consistent in your use of the WAL ? >> > >> > >> > On Nov 21, 2012, at 6:37 AM, Bing Jiang <[email protected]> >> wrote: >> > >> > > hi，all. >> > > I want to describe a phenomenon that happens to our hbase cluster. >> > > I use puts(List<Put>) to insert many records with writing hlog enable, >> > > and some time later I delete all of these records with writing hlog >> > disable. >> > > When one week later, i scan the table, I found some records I have >> delete >> > > reappear again. >> > > It is an interesting case. In my opinion, if we delete data without >> > enable >> > > writing hlog, when regionserver fails, the log will replay in another >> > > regionserver. >> > > Can anyone tell me if I persist on deleting records without enable >> > writing >> > > hlog, is there a way to prevent these records from reappearing again >> some >> > > time later? >> > > >> > > Cheers! >> > > -- >> > > Bing Jiang >> > > weibo: http://weibo.com/jiangbinglover >> > > BLOG: http://blog.sina.com.cn/jiangbinglover >> > > BLOG: http://www.binospace.com >> > > National Research Center for Intelligent Computing Systems >> > > Institute of Computing technology >> > > Graduate University of Chinese Academy of Science >> > >> > >> > > > > -- > Bing Jiang > Tel：(86)134-2619-1361 > > weibo: http://weibo.com/jiangbinglover > BLOG: http://blog.sina.com.cn/jiangbinglover > National Research Center for Intelligent Computing Systems > Institute of Computing technology > Graduate University of Chinese Academy of Science > > -- Bing Jiang Tel：(86)134-2619-1361 weibo: http://weibo.com/jiangbinglover BLOG: http://blog.sina.com.cn/jiangbinglover National Research Center for Intelligent Computing Systems Institute of Computing technology Graduate University of Chinese Academy of Science
