When a file gets written to hdfs, there is a guarantee the file is local as long as that systems disks are not full. Accumulo does not have a locality guarantee as tablets will migrate on occasion. However, as data is added, major compactions will occur which will restore locality. On Dec 12, 2012 1:09 PM, "ameet kini" <[email protected]> wrote:
> > Along these lines.... > > Can someone help me understand how tablets map to files on disk in HDFS? > From what I understand, after a compaction, there may be one (or more?) > files on HDFS for a given tablet. Each file can consist of multiple HDFS > blocks. Does Accumulo guarantee that the tablet serving a given data range > finds all its blocks locally? If so, how does it keep this guarantee? > Wouldn't HDFS distribute these blocks around based on HDFS balancing > strategy? > > Thanks, > Ameet > > On Tue, Dec 11, 2012 at 9:37 AM, William Slacum < > [email protected]> wrote: > >> Tablets will split automatically, down to the granularity of a row. >> >> >> On Tue, Dec 11, 2012 at 9:32 AM, Mathias Herberts < >> [email protected]> wrote: >> >>> Hi, >>> >>> I've read the user manual for v1.4.2 and I have not seen any mention of >>> automatic tablet splitting. Is there such a thing in Accumulo or is >>> pre-splitting the only way to split a table? >>> >>> Thanks, >>> >>> Mathias. >>> >> >> >
