Hi First time this issue was reported, I felt bad because HBASE-5155 was introduced by me. I sincerely apologize for the mistake that I did. Because of my mistake I think all you guys are trying to do some workarounds. Sorry for pitching in late to this thread as I was not in town to access mails.
Next time I share surely be careful in such things. Regards Ram > -----Original Message----- > From: Gregory Chanan [mailto:[email protected]] > Sent: Saturday, September 01, 2012 10:00 AM > To: [email protected]; lars hofhansl > Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > I filed HBASE-6710. > > Greg > > On Fri, Aug 31, 2012 at 8:21 PM, lars hofhansl <[email protected]> > wrote: > > > I see. Makes sense. I made a trivial 0.94 patch for HBASE-6268. > > Can you file a jira for the other changes you describe below? > > > > -- Lars > > > > > > > > ________________________________ > > From: Gregory Chanan <[email protected]> > > To: [email protected]; lars hofhansl <[email protected]> > > Sent: Friday, August 31, 2012 7:42 PM > > Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > > > @Lars: agreed on your point of leaving the name for the 92 znode the > same. > > > > On upgrading a 0.94.0 or 0.94.1 cluster out of sync, I think it would > work. > > The 0.94.2 client should work against all 0.94.2, 0.94.1, and 0.94.0 > > versions (and all 0.92.x versions as well). We just need to apply > > HBASE-6268 to 0.94.2. So you would first upgrade the client, then > the > > server(s). The reason this works is because the client, with HBASE- > 6268 > > applied, can handle the znode being in either the 0.92 or 0.94 > format, it > > doesn't need to know which is which. I'll of course test all this > :). > > > > Greg > > > > On Fri, Aug 31, 2012 at 7:02 PM, lars hofhansl <[email protected]> > > wrote: > > > > > Also, if understand this correctly this would not help if somebody > had > > > deployed an 0.94.0 or 0.94.1 cluster and want to upgrade the client > and > > > server out of sync. > > > In one configuration the client would work against 0.94.0 and > 0.94.1 but > > > not against 0.94.2. In the other configuration the client would > work > > > against 0.94.2 but not against 0.94.0 or 0.94.1. > > > > > > > > > There is however and clean upgrade path to 0.92.2 and from there to > > 0.94.2 > > > if we just fix this in 0.92.2. > > > > > > > > > -- Lars > > > > > > > > > > > > ________________________________ > > > From: lars hofhansl <[email protected]> > > > To: Gregory Chanan <[email protected]>; "[email protected]" < > > > [email protected]> > > > Sent: Friday, August 31, 2012 6:34 PM > > > Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > > > > > Sounds complicated. But since you are the folks with customers > that'll > > > upgrade to from 0.92 to 0.94, let's do this. > > > > > > The only input I'd have is that format we'll use going forward will > not > > > have a version attached to it. > > > > > > So maybe the 92 version would still be called > > > "zookeeper.znode.tableEnableDisable" and the new node could have a > > > different name "zookeeper.znode.tableEnableDisableNew" (or > something). > > > > > > -- Lars > > > > > > > > > > > > ________________________________ > > > From: Gregory Chanan <[email protected]> > > > To: [email protected]; lars hofhansl <[email protected]> > > > Sent: Friday, August 31, 2012 5:54 PM > > > Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > > > > > > > > Actually, I think we can make 0.94.2 compatible with both > {0.94.0,0.94.1} > > > and {0.92.0,0.92.1}, although one of those sets will require > > configuration > > > changes. > > > > > > The basic problem is that there is a znode for each table > > > "zookeeper.znode.tableEnableDisable" that is handled differently. > > > > > > On 0.92.0 and 0.92.1 the states for this table are: > > > [ disabled, disabling, enabling ] or deleted if the table is > enabled > > > > > > On 0.94.1 and 0.94.2 the states for this table are: > > > [ disabled, disabling, enabling, enabled ] > > > > > > What saves us is that the location of this znode is configurable. > So the > > > basic idea is to have the 0.94.2 master write two different znodes, > > > "zookeeper.znode.tableEnableDisabled92" and > > > "zookeeper.znode.tableEnableDisabled94" where the 92 node is in 92 > > format, > > > the 94 node is in 94 format. And internally, the master would only > use > > the > > > 94 format in order to solve the original bug HBASE-5155 solves. > > > We can of course make one of these the same default as exists now, > so we > > > don't need to make config changes for one of 0.92 or 0.94 clients. > I > > argue > > > that 0.92 clients shouldn't have to make config changes for the > same > > reason > > > I argued above. But that is debatable. > > > > > > Then, I think the only question left is Stack's question of how to > bring > > > along the {0.94.0, 0.94.1} crew. A {0.94.0, 0.94.1} client would > work > > > against a 0.94.2 cluster by just > > > configuring "zookeeper.znode.tableEnableDisable" in the client to > be > > > whatever "zookeeper.znode.tableEnableDisabled94" is in the cluster. > A > > > 0.94.2 client would work against both a {0.94.0, 0.94.1} and > {0.92.0, > > > 0.92.1} cluster if it had HBASE-6268 applied. About rolling > upgrade from > > > {0.94.0, 0.94.1} to 0.94.2 -- I'd have to think about that. Do the > > > regionservers ever read the tableEnableDisabled znode? > > > > > > Greg > > > > > > On Fri, Aug 31, 2012 at 4:41 PM, lars hofhansl > <[email protected]> > > > wrote: > > > > > > I guess you voiced your opinion in your initial email already (you > prefer > > > to break compatibility between 0.94.0/0.94.1 with 0.94.2). > > > >If that is indeed the consensus, please file a jira against > 0.94.2. > > > > > > > >-- Lars > > > > > > > > > > > > > > > > > > > >----- Original Message ----- > > > >From: lars hofhansl <[email protected]> > > > >To: "[email protected]" <[email protected]> > > > >Cc: > > > >Sent: Friday, August 31, 2012 4:24 PM > > > >Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > > > > > > >What do you think we should do? > > > > > > > >1. Breaking compatibility between minor versions is bad. (i.e. we > should > > > fix this in 0.92.2 as currently proposed) > > > >2. At the same time 0.92 might be in wider distribution and that > the > > > upgrade path 0.94 might be more important (and include the fix that > you > > > propose). > > > > > > > >I'm +1 on #1 and +0 on #2. > > > > > > > > > > > >I agree we need better cross-version integration testing and be > > generally > > > more diligent about this. > > > > > > > >-- Lars > > > >________________________________ > > > >From: Gregory Chanan <[email protected]> > > > >To: [email protected] > > > >Cc: lars hofhansl <[email protected]> > > > >Sent: Friday, August 31, 2012 4:06 PM > > > >Subject: Re: 0.92/0.94 compatibility and HBASE-5206 > > > > > > > >@Lars: > > > >you are correct that this would break compatibility between > {0.94.0, > > > >0.94.1} and 0.94.2. > > > > > > > >We clearly need better compatibility testing, these issues are > hard to > > > find > > > >by just looking at patches. > > > > > > > >Greg > > > > > > > >On Fri, Aug 31, 2012 at 4:03 PM, Ted Yu <[email protected]> > wrote: > > > > > > > >> I should also apologize for HBASE-5206 where I didn't maintain > > > >> compatibility in the first place. > > > >> > > > >> We just need to find the solution which minimizes impact of this > > issue. > > > >> > > > >> Cheers > > > >> > > > >> On Fri, Aug 31, 2012 at 3:55 PM, lars hofhansl > <[email protected]> > > > >> wrote: > > > >> > > > >> > Won't we then break compatibility between 0.94.0 and 0.94.1 > with > > > 0.94.2? > > > >> > I do not have a strong opinion about this. > > > >> > > > > >> > It was my fault that HBASE-5206 slipped into 0.94.0, I > apologize for > > > >> that. > > > >> > > > > >> > I was going to spin the first 0.94.2 today. Is the general > consensus > > > that > > > >> > I should wait? > > > >> > > > > >> > > > > >> > -- Lars > > > >> > > > > >> > > > > >> > > > > >> > ________________________________ > > > >> > From: Gregory Chanan <[email protected]> > > > >> > To: [email protected] > > > >> > Sent: Friday, August 31, 2012 3:13 PM > > > >> > Subject: 0.92/0.94 compatibility and HBASE-5206 > > > >> > > > > >> > There has been some discussion on the JIRA lately about what > to do > > > about > > > >> a > > > >> > 0.92/0.94 compatibility issue. I wanted to bring this up to a > > larger > > > >> > audience in order to solicit additional opinions. > > > >> > > > > >> > HBASE-5206 (https://issues.apache.org/jira/browse/HBASE-5206), > > which > > > is > > > >> in > > > >> > 0.94.0 and 0.94.1, breaks compatibility with 0.92.0 and > 0.92.1. The > > > >> issue > > > >> > is described in the release notes for HBASE-5155 (of which > > HBASE-5206 > > > is > > > >> a > > > >> > forward port). Excerpted here: > > > >> > > > > >> > This issue is an incompatible change. > > > >> > If an HBase client with the changes for HBASE-5155 and a > server > > > >> (master) > > > >> > without the changes for HBASE-5155 is used, then the > is_enabled > > (from > > > >> HBase > > > >> > Shell) or isTableEnabled() (from HBaseAdmin) will return false > > though > > > the > > > >> > table is already enabled as per the master. > > > >> > > > > >> > If the HBase client does have the changes for HBASE-5155 and > the > > > server > > > >> > does not have the changes for HBASE-5155, then if we try to > Enable a > > > >> table > > > >> > then the client will hang. > > > >> > > > > >> > The reason is because, > > > >> > Prior to HBASE-5155 once the table is enabled the znode in > the > > > >> zookeeper > > > >> > created for the table is deleted. > > > >> > After HBASE-5155 once the table is enabled the znode in the > > > zookeeper > > > >> > created for the table is not deleted, whereas the same node is > > updated > > > >> with > > > >> > the status ENABLED. > > > >> > > > > >> > The client also expects the status of the znode in the > zookeeper > > to > > > be > > > >> in > > > >> > the ENABLED state if the table has been enabled successfully. > > > >> > The above changes makes the client behaviour incompatible if > the > > > client > > > >> > does not have this fix whereas the server has this fix. > > > >> > If both the client and the server does not have this fix, > then the > > > >> > behaviour is as expected. > > > >> > > > > >> > So we have a situation where 0.92.0 and 0.92.1 clients are not > > > compatible > > > >> > with 0.94.0 and 0.94.1 servers and visa-versa. > > > >> > > > > >> > The issue is, what should we do about the 0.94.2 server? As > far as > > I > > > can > > > >> > tell, we cannot make both {0.92.0,0.92.1} and {0.94.0,0.94.1} > > clients > > > >> > happy. I propose we make the 0.94.2 server compatible with > the > > > {0.92.0, > > > >> > 0.92.1} client set. My thinking is that we should optimize > for the > > > most > > > >> > common use case. Given that both CDH4 and HDP 1.0 ship > 0.92.1, and > > > that > > > >> > 0.94 is relatively new, it seems more likely that users will > upgrade > > > >> > servers from 0.92.1 to 0.94.2+ than from an earlier 0.94 > version. I > > > >> think > > > >> > we can do this while actually fixing the issue that HBASE-5206 > > > purports > > > >> to > > > >> > fix by moving the ENABLED state to a different znode. I'll > even > > > >> volunteer > > > >> > to do that :). I don't think there is an obvious or easy > answer > > > here, so > > > >> > wanted to get other's opinions. > > > >> > > > > >> > As for the client, HBASE-6268 ( > > > >> > https://issues.apache.org/jira/browse/HBASE-6268) was > introduced in > > > >> 0.92.2 > > > >> > to handle both cases of servers ({0.92.0,0.92.1} and > > {0.94.0,0.94.1}) > > > by > > > >> > accepting both possibilities for the table znode. I think > that > > > approach > > > >> > works whether we leave the server as is or go with what I've > > proposed > > > -- > > > >> > but we should test. > > > >> > > > > >> > Greg > > > >> > > > > > > > > > > > > >
