2012/4/13 Florin P <florinp...@yahoo.com>: > Hello! > Thank you all for all responses. It is possible to have a matrix of > hadoop > file input format that supports append or if I understood correctly, all > formats are now supporting append? > Thanks a lot. > Regards, > Florin
Hi Florin, Append is a file-system feature not a file format feature although some file formats are designed to be immutable (MapFile, HFile). You can append to them, just don't use the interface they normally provide. > ________________________________ > From: Inder Pall <inder.p...@gmail.com> > To: hdfs-user@hadoop.apache.org > Sent: Tuesday, April 10, 2012 8:12 AM > Subject: Re: Is append allowed in HDFS? > > Harsh, > > idea is to call sync for a configured batch. Still under implementation as > other parts of the system's aren't complete. > > recovery/resume-from-errors-at-DN code around general tail-like >>>This sounds promising, can you please shed some more light on this. > > - inder > On Tue, Apr 10, 2012 at 1:07 AM, Harsh J <ha...@cloudera.com> wrote: > > Your approach looks fine to me. I'd throw in some > recovery/resume-from-errors-at-DN code around general tail-like > consumption but I think you may have already done that :) > > But just for my curiosity - do you call sync for every record/unit or > batch it by a few, for your problem? > > On Mon, Apr 9, 2012 at 10:34 PM, Inder Pall <inder.p...@gmail.com> wrote: >> Yes makes sense. My use-case is more like a producer/consumer and >> consumer >> trying to stream data as it arrives. >> Has anyone hit this before and if so resolved it in a better way. >> >> Apologies, if i am digressing from the subject of this thread however >> seems >> to land in the bucket of append support in HDFS. >> >> - Inder >> >> >> On Mon, Apr 9, 2012 at 6:27 PM, Harsh J <ha...@cloudera.com> wrote: >>> >>> Inder, >>> >>> Yes, that is a requirement for readers of sync-ing data. The new meta >>> entries can only be read by new readers. The read code would end up >>> being exactly like the implementation for method "fs -tail" at >>> >>> >>> >>> http://svn.apache.org/viewvc/hadoop/common/branches/branch-1/src/core/org/apache/hadoop/fs/FsShell.java?view=markup >>> (Line 1101) >>> >>> HBase does not read the WAL (HLog) continuously/vigorously as it >>> syncs, by the way. It only reads the them when a specific request is >>> made (for splitting, replaying and debug-printing). >>> >>> On Mon, Apr 9, 2012 at 6:05 PM, Inder Pall <inder.p...@gmail.com> wrote: >>> > Based on what i have tried, after a sync you need to open a new >>> > Reader. >>> > Please correct if that's not the write semantics. >>> > >>> > Thanks, >>> > - Inder >>> > >>> > >>> > On Mon, Apr 9, 2012 at 4:23 PM, Harsh J <ha...@cloudera.com> wrote: >>> >> >>> >> I'd also like to note that there are some unresolved issues with the >>> >> append version in the 1.x (stable) line. >>> >> >>> >> Note that HBase's use of the 0.20-append branch features are limited >>> >> to using "sync" calls alone (Described in p68 "Coherency Model", >>> >> Chapter 3 (The Hadoop Distributed File System) in Hadoop: The >>> >> Definitive Guide, 2nd Edition (O'Reilly)). Not the file-reopening >>> >> "append" calls. The latter is what is still with issues in the 1.x >>> >> releases today. Using the former is alright if its done in the way >>> >> similar to HBase's WAL (HLog) (or for similar needs). >>> >> >>> >> On Mon, Apr 9, 2012 at 3:45 PM, Ioan Eugen Stan >>> >> <stan.ieu...@gmail.com> >>> >> wrote: >>> >> > 2012/4/7 Florin P <florinp...@yahoo.com>: >>> >> >> Hello! >>> >> >> Just google it for supporting of append into HDFS files and the >>> >> >> result: >>> >> >> I'm puzzled. Can someone say: YES you can append in TextFile or >>> >> >> SequenceFile >>> >> >> or whatever format. If yes, in which version this feature is >>> >> >> supported >>> >> >> ? >>> >> >> Also where can I find a good example of using the API? I know that >>> >> >> is a >>> >> >> long >>> >> >> debate about this subject, but really it is challenge to find on >>> >> >> the >>> >> >> google >>> >> >> the current status of this feature. >>> >> >> I look forward for a trust source answer. >>> >> >> Thank you, >>> >> >> Regards, >>> >> >> Florin >>> >> > >>> >> > Hi Florian, >>> >> > >>> >> > HDFS supports append in Hadoop 1.0.x branch and also 0.22 (a.k.a >>> >> > hadoop 2.x branch) and 0.23 (a.k.a hadoop 3.x branch). >>> >> > >>> >> > [1] http://hbase.apache.org/book/hadoop.html >>> >> > [2] http://hbase.apache.org/book/hadoop.html -- search for append >>> >> > in >>> >> > release notes >>> >> > >>> >> > Cheers, >>> >> > -- >>> >> > Ioan Eugen Stan >>> >> > http://ieugen.blogspot.com/ >>> >> >>> >> >>> >> >>> >> -- >>> >> Harsh J >>> > >>> > >>> > >>> > >>> > -- >>> > Thanks, >>> > - Inder >>> > Tech Platforms @Inmobi >>> > Linkedin - http://goo.gl/eR4Ub >>> >>> >>> >>> -- >>> Harsh J >> >> >> >> >> -- >> Thanks, >> - Inder >> Tech Platforms @Inmobi >> Linkedin - http://goo.gl/eR4Ub > > > > -- > Harsh J > > > > > -- > Thanks, > - Inder > Tech Platforms @Inmobi > Linkedin - http://goo.gl/eR4Ub > > -- Ioan Eugen Stan http://ieugen.blogspot.com/
