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
