Yes, 10247 is precisely where we should have this discussion. Thanks for pointing it out.
On Thu, Apr 10, 2014 at 8:22 PM, lars hofhansl <la...@apache.org> wrote: > Should we discuss this here: > https://issues.apache.org/jira/browse/HBASE-10247? > > > > ________________________________ > From: Sergey Shelukhin <ser...@hortonworks.com> > To: dev@hbase.apache.org > Sent: Thursday, April 10, 2014 6:16 PM > Subject: Re: Disambiguate cell time for 1.0 > > > Adding nonces to deletes and puts is possible, but it is overhead... > > > > On Thu, Apr 10, 2014 at 6:16 PM, Sergey Shelukhin <ser...@hortonworks.com > >wrote: > > > Just to clarify what I was saying, there was a JIRA where we were > > discussing this. > > Server clocks are unreliable and when region moves (or if we have > writable > > replicas) between-server clocks are even more sor. > > So we cannot really promise consistency wrt order even for requests from > > the same client now; even if we manage TS 100%. > > My suggestion was that we have 3 modes: (1) we manage TS on server => TS > > gets written as seqNum which has guarantees, no client-supplied TS; (2) > > client manages TS and supplies it, fail put if no TS; (3) legacy compat > > mode, but TS is generated in the client library instead of RS, so the > onus > > is on the client app/client's server to manage clocks and there's no > > expectation that HBase will guarantee order. > > > > > > > > On Thu, Apr 10, 2014 at 5:09 PM, Nick Dimiduk <ndimi...@gmail.com> > wrote: > > > >> Reading through the write path, it seems to me that > >> RSRpcServices#doBatchOp(RegionActionResult.Builder,HRegion,List<Action> > >> mutations,CellScanner) should be honoring a nonce if present. The reason > >> being: if a client sends some Puts without specifying a TS, it relies on > >> the RS to provide one. Should such an operation succeed on the server > but > >> the ACK not reach the client, client may resend the operation, silently > >> inserting more cells than intended. Deletes may well be a more sinister > >> issue, removing more cells than intended. > >> > >> I've not yet written a test to confirm this. > >> > >> There was conversation around the implementation of nonces discussing > >> options for removing the coupling of TS to clock-on-the-wall time. > Sergey > >> describes the current situation quite eloquently: "server-generated TS > >> provide illusion of consistency guarantees which is not there by any > >> means". A fix for this will likely subtly break the semantics of our > data > >> coordinates, and so should be addressed with 1.0, perhaps along side a > >> revamped client-side API. > >> > >> -n > >> > > > > > > -- > CONFIDENTIALITY NOTICE > NOTICE: This message is intended for the use of the individual or entity to > which it is addressed and may contain information that is confidential, > privileged and exempt from disclosure under applicable law. If the reader > of this message is not the intended recipient, you are hereby notified that > any printing, copying, dissemination, distribution, disclosure or > forwarding of this communication is strictly prohibited. If you have > received this communication in error, please contact the sender immediately > and delete it from your system. Thank You. >
