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: > > > hiļ¼all. > > 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 > >
