-------- Original Message -------- From: Wellington Chevreuil <[email protected]> Sent: Thursday, July 17, 2014 04:34 AM To: [email protected] Subject: Re: Replace a block with a new one
>Hi, > >there's no way to do that, as HDFS does not provide file updates features. >You'll need to write a new file with the changes. > >Notice that even if you manage to find the physical block replica files on the >disk, corresponding to the part of the file you want to change, you can't >simply update it manually, as this would give a different checksum, making >HDFS mark such blocks as corrupt. > >Regards, >Wellington. > > > >On 17 Jul 2014, at 10:50, Zesheng Wu <[email protected]> wrote: > >> Hi guys, >> >> I recently encounter a scenario which needs to replace an exist block with a >> newly written block >> The most straightforward way to finish may be like this: >> Suppose the original file is A, and we write a new file B which is composed >> by the new data blocks, then we merge A and B to C which is the file we >> wanted >> The obvious shortcoming of this method is wasting of network bandwidth >> >> I'm wondering whether there is a way to replace the old block by the new >> block directly. >> Any thoughts? >> >> -- >> Best Wishes! >> >> Yours, Zesheng >
