Re: How practical is it to add a timestamp oracle on Zookeeper
Hi, I presume you have read the percolator paper. The design there uses a single ts oracle, and BigTable itself as the transaction manager. In omid, they also have a TS oracle, but I do not know how scalable it is. But using ZK as the TS oracle would not work, since ZK can scale up to 40-50K requests per second, but depending on the cluster size, you should be getting much more than that. Especially considering all clients doing reads and writes has to obtain a TS. Instead what you want is a TS that can scale to millions of requests per sec. This can be achieved by the technique in the percolator paper, by pre allocating a range by persisting to disk, and an extremely lightweight rpc. I do not know whether Omid provides this. There is a twitter project https://github.com/twitter/snowflake that you might want to look at. Hope this helps. Enis On Sun, Apr 21, 2013 at 9:36 AM, Michel Segel wrote: > Time is relative. > What does the timestamp mean? > > Sounds like a simple question, but its not. Is it the time your > application says they wrote to HBase? Is it the time HBase first gets the > row? Or is it the time that the row was written to the memstore? > > Each RS has its own clock in addition to your app server. > > > Sent from a remote device. Please excuse any typos... > > Mike Segel > > On Apr 16, 2013, at 7:14 AM, yun peng wrote: > > > Hi, All, > > I'd like to add a global timestamp oracle on Zookeep to assign globally > > unique timestamp for each Put/Get issued from HBase cluster. The reason I > > put it on Zookeeper is that each Put/Get needs to go through it and > unique > > timestamp needs some global centralised facility to do it. But I am > asking > > how practical is this scheme, like anyone used in practice? > > > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > > code path of HBase inside Zookeeper. I know HBase has Coprocessor on > region > > server to let programmer to extend without recompiling HBase itself. Does > > Zk allow such extensibility? Thanks. > > > > Regards > > Yun >
Re: How practical is it to add a timestamp oracle on Zookeeper
Time is relative. What does the timestamp mean? Sounds like a simple question, but its not. Is it the time your application says they wrote to HBase? Is it the time HBase first gets the row? Or is it the time that the row was written to the memstore? Each RS has its own clock in addition to your app server. Sent from a remote device. Please excuse any typos... Mike Segel On Apr 16, 2013, at 7:14 AM, yun peng wrote: > Hi, All, > I'd like to add a global timestamp oracle on Zookeep to assign globally > unique timestamp for each Put/Get issued from HBase cluster. The reason I > put it on Zookeeper is that each Put/Get needs to go through it and unique > timestamp needs some global centralised facility to do it. But I am asking > how practical is this scheme, like anyone used in practice? > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > code path of HBase inside Zookeeper. I know HBase has Coprocessor on region > server to let programmer to extend without recompiling HBase itself. Does > Zk allow such extensibility? Thanks. > > Regards > Yun
Re: How practical is it to add a timestamp oracle on Zookeeper
I think Yun wants some global timestamp, not uniq ids. This is doable, technically. However, not sure what's the performance requirement. Thanks, Jimmy On Sun, Apr 21, 2013 at 9:22 AM, kishore g wrote: > Its probably not practical to do this for every put. Instead each client > can get a chunk of ids, and use it for every put. Each chunk of ids will > be mutually exclusive and monotonically increases. You need to know that > there can be holes in ids and ids will not be according to timestamp within > a small interval > > If I remember correctly, tweet ids are generated like this. Take a look at > snowflake https://github.com/twitter/snowflake > > > thanks, > Kishore G > > > On Sun, Apr 21, 2013 at 8:10 AM, PG wrote: > > > Hi, ted and JM, Thanks for the nice introduction. I have read the Omid > > paper, which looks use a centralized party to do the coordination and > > achieves 72K transactions per sec. And It does much more work than just > > assigning timestamps, and I think it implicitly justifies the usage of a > > global timestamp oracle in practice Appreciate the suggestion. > > Regards, > > Yun > > > > Sent from my iPad > > > > On Apr 16, 2013, at 9:31 AM, Jean-Marc Spaggiari < > jean-m...@spaggiari.org> > > wrote: > > > > > Hi Yun, > > > > > > Attachements are not working on the mailing list. However, everyone > > > using HBase should have the book on its desk, so I have ;) > > > > > > On the figure 8-11, you can see that client wil contact ZK to know > > > where the root region is. Then the root region to find the meta, and > > > so on. > > > > > > BUT This will be done only once per client! If you do 10 gets from > > > your client, once you know where the root region is, you don't need to > > > query ZK anymore. It will be cached locally. > > > > > > For your usecase, you might want to take a look at what Ted send. > > > https://github.com/yahoo/omid/wiki I looked a it quickly and seems to > > > be a good fit for you. > > > > > > JM > > > > > > 2013/4/16 yun peng : > > >> Hi, Jean and Jieshan, > > >> Are you saying client can directly contact region servers? Maybe I > > >> overlooked, but I think the client may need lookup regions by first > > >> contacting Zk as in figure 8-11 from definitive book(as attached)... > > >> > > >> Nevertheless, if it is the case, to assign a global timestamp, what is > > the > > >> practical solutions in real production today? since it still needs > some > > >> centralised facility.. Please enlighten me. thanks. > > >> Regards > > >> Yun > > >> > > >> > > >> > > >> > > >> On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari > > >> wrote: > > >>> > > >>> Hi Yun, > > >>> > > >>> If I understand you correctly, that mean that each time our are going > > to > > >>> do > > >>> a put or a get you will need to call ZK first? > > >>> > > >>> Since ZK has only one master active, that mean that this ZK master > > will be > > >>> called for each HBase get/put? > > >>> > > >>> You are going to create a bottle neck there. I don't know how many RS > > you > > >>> have, but you will certainly hotspot you ZK server. I'm not sure > it's a > > >>> good idea. > > >>> > > >>> JM > > >>> > > >>> 2013/4/16 yun peng > > >>> > > Hi, All, > > I'd like to add a global timestamp oracle on Zookeep to assign > > globally > > unique timestamp for each Put/Get issued from HBase cluster. The > > reason > > I > > put it on Zookeeper is that each Put/Get needs to go through it and > > unique > > timestamp needs some global centralised facility to do it. But I am > > asking > > how practical is this scheme, like anyone used in practice? > > > > Also, how difficulty is it to extend Zookeeper, or to inject code to > > the > > code path of HBase inside Zookeeper. I know HBase has Coprocessor on > > region > > server to let programmer to extend without recompiling HBase itself. > > Does > > Zk allow such extensibility? Thanks. > > > > Regards > > Yun > > > > >> > > >> > > >
Re: How practical is it to add a timestamp oracle on Zookeeper
Its probably not practical to do this for every put. Instead each client can get a chunk of ids, and use it for every put. Each chunk of ids will be mutually exclusive and monotonically increases. You need to know that there can be holes in ids and ids will not be according to timestamp within a small interval If I remember correctly, tweet ids are generated like this. Take a look at snowflake https://github.com/twitter/snowflake thanks, Kishore G On Sun, Apr 21, 2013 at 8:10 AM, PG wrote: > Hi, ted and JM, Thanks for the nice introduction. I have read the Omid > paper, which looks use a centralized party to do the coordination and > achieves 72K transactions per sec. And It does much more work than just > assigning timestamps, and I think it implicitly justifies the usage of a > global timestamp oracle in practice Appreciate the suggestion. > Regards, > Yun > > Sent from my iPad > > On Apr 16, 2013, at 9:31 AM, Jean-Marc Spaggiari > wrote: > > > Hi Yun, > > > > Attachements are not working on the mailing list. However, everyone > > using HBase should have the book on its desk, so I have ;) > > > > On the figure 8-11, you can see that client wil contact ZK to know > > where the root region is. Then the root region to find the meta, and > > so on. > > > > BUT This will be done only once per client! If you do 10 gets from > > your client, once you know where the root region is, you don't need to > > query ZK anymore. It will be cached locally. > > > > For your usecase, you might want to take a look at what Ted send. > > https://github.com/yahoo/omid/wiki I looked a it quickly and seems to > > be a good fit for you. > > > > JM > > > > 2013/4/16 yun peng : > >> Hi, Jean and Jieshan, > >> Are you saying client can directly contact region servers? Maybe I > >> overlooked, but I think the client may need lookup regions by first > >> contacting Zk as in figure 8-11 from definitive book(as attached)... > >> > >> Nevertheless, if it is the case, to assign a global timestamp, what is > the > >> practical solutions in real production today? since it still needs some > >> centralised facility.. Please enlighten me. thanks. > >> Regards > >> Yun > >> > >> > >> > >> > >> On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari > >> wrote: > >>> > >>> Hi Yun, > >>> > >>> If I understand you correctly, that mean that each time our are going > to > >>> do > >>> a put or a get you will need to call ZK first? > >>> > >>> Since ZK has only one master active, that mean that this ZK master > will be > >>> called for each HBase get/put? > >>> > >>> You are going to create a bottle neck there. I don't know how many RS > you > >>> have, but you will certainly hotspot you ZK server. I'm not sure it's a > >>> good idea. > >>> > >>> JM > >>> > >>> 2013/4/16 yun peng > >>> > Hi, All, > I'd like to add a global timestamp oracle on Zookeep to assign > globally > unique timestamp for each Put/Get issued from HBase cluster. The > reason > I > put it on Zookeeper is that each Put/Get needs to go through it and > unique > timestamp needs some global centralised facility to do it. But I am > asking > how practical is this scheme, like anyone used in practice? > > Also, how difficulty is it to extend Zookeeper, or to inject code to > the > code path of HBase inside Zookeeper. I know HBase has Coprocessor on > region > server to let programmer to extend without recompiling HBase itself. > Does > Zk allow such extensibility? Thanks. > > Regards > Yun > > >> > >> >
Re: How practical is it to add a timestamp oracle on Zookeeper
Hi, ted and JM, Thanks for the nice introduction. I have read the Omid paper, which looks use a centralized party to do the coordination and achieves 72K transactions per sec. And It does much more work than just assigning timestamps, and I think it implicitly justifies the usage of a global timestamp oracle in practice Appreciate the suggestion. Regards, Yun Sent from my iPad On Apr 16, 2013, at 9:31 AM, Jean-Marc Spaggiari wrote: > Hi Yun, > > Attachements are not working on the mailing list. However, everyone > using HBase should have the book on its desk, so I have ;) > > On the figure 8-11, you can see that client wil contact ZK to know > where the root region is. Then the root region to find the meta, and > so on. > > BUT This will be done only once per client! If you do 10 gets from > your client, once you know where the root region is, you don't need to > query ZK anymore. It will be cached locally. > > For your usecase, you might want to take a look at what Ted send. > https://github.com/yahoo/omid/wiki I looked a it quickly and seems to > be a good fit for you. > > JM > > 2013/4/16 yun peng : >> Hi, Jean and Jieshan, >> Are you saying client can directly contact region servers? Maybe I >> overlooked, but I think the client may need lookup regions by first >> contacting Zk as in figure 8-11 from definitive book(as attached)... >> >> Nevertheless, if it is the case, to assign a global timestamp, what is the >> practical solutions in real production today? since it still needs some >> centralised facility.. Please enlighten me. thanks. >> Regards >> Yun >> >> >> >> >> On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari >> wrote: >>> >>> Hi Yun, >>> >>> If I understand you correctly, that mean that each time our are going to >>> do >>> a put or a get you will need to call ZK first? >>> >>> Since ZK has only one master active, that mean that this ZK master will be >>> called for each HBase get/put? >>> >>> You are going to create a bottle neck there. I don't know how many RS you >>> have, but you will certainly hotspot you ZK server. I'm not sure it's a >>> good idea. >>> >>> JM >>> >>> 2013/4/16 yun peng >>> Hi, All, I'd like to add a global timestamp oracle on Zookeep to assign globally unique timestamp for each Put/Get issued from HBase cluster. The reason I put it on Zookeeper is that each Put/Get needs to go through it and unique timestamp needs some global centralised facility to do it. But I am asking how practical is this scheme, like anyone used in practice? Also, how difficulty is it to extend Zookeeper, or to inject code to the code path of HBase inside Zookeeper. I know HBase has Coprocessor on region server to let programmer to extend without recompiling HBase itself. Does Zk allow such extensibility? Thanks. Regards Yun >> >>
Re: How practical is it to add a timestamp oracle on Zookeeper
Hi Yun, Attachements are not working on the mailing list. However, everyone using HBase should have the book on its desk, so I have ;) On the figure 8-11, you can see that client wil contact ZK to know where the root region is. Then the root region to find the meta, and so on. BUT This will be done only once per client! If you do 10 gets from your client, once you know where the root region is, you don't need to query ZK anymore. It will be cached locally. For your usecase, you might want to take a look at what Ted send. https://github.com/yahoo/omid/wiki I looked a it quickly and seems to be a good fit for you. JM 2013/4/16 yun peng : > Hi, Jean and Jieshan, > Are you saying client can directly contact region servers? Maybe I > overlooked, but I think the client may need lookup regions by first > contacting Zk as in figure 8-11 from definitive book(as attached)... > > Nevertheless, if it is the case, to assign a global timestamp, what is the > practical solutions in real production today? since it still needs some > centralised facility.. Please enlighten me. thanks. > Regards > Yun > > > > > On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari > wrote: >> >> Hi Yun, >> >> If I understand you correctly, that mean that each time our are going to >> do >> a put or a get you will need to call ZK first? >> >> Since ZK has only one master active, that mean that this ZK master will be >> called for each HBase get/put? >> >> You are going to create a bottle neck there. I don't know how many RS you >> have, but you will certainly hotspot you ZK server. I'm not sure it's a >> good idea. >> >> JM >> >> 2013/4/16 yun peng >> >> > Hi, All, >> > I'd like to add a global timestamp oracle on Zookeep to assign globally >> > unique timestamp for each Put/Get issued from HBase cluster. The reason >> > I >> > put it on Zookeeper is that each Put/Get needs to go through it and >> > unique >> > timestamp needs some global centralised facility to do it. But I am >> > asking >> > how practical is this scheme, like anyone used in practice? >> > >> > Also, how difficulty is it to extend Zookeeper, or to inject code to the >> > code path of HBase inside Zookeeper. I know HBase has Coprocessor on >> > region >> > server to let programmer to extend without recompiling HBase itself. >> > Does >> > Zk allow such extensibility? Thanks. >> > >> > Regards >> > Yun >> > > >
Re: How practical is it to add a timestamp oracle on Zookeeper
Hi, Jean and Jieshan, Are you saying client can directly contact region servers? Maybe I overlooked, but I think the client may need lookup regions by first contacting Zk as in figure 8-11 from definitive book(as attached)... Nevertheless, if it is the case, to assign a global timestamp, what is the practical solutions in real production today? since it still needs some centralised facility.. Please enlighten me. thanks. Regards Yun On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari < jean-m...@spaggiari.org> wrote: > Hi Yun, > > If I understand you correctly, that mean that each time our are going to do > a put or a get you will need to call ZK first? > > Since ZK has only one master active, that mean that this ZK master will be > called for each HBase get/put? > > You are going to create a bottle neck there. I don't know how many RS you > have, but you will certainly hotspot you ZK server. I'm not sure it's a > good idea. > > JM > > 2013/4/16 yun peng > > > Hi, All, > > I'd like to add a global timestamp oracle on Zookeep to assign globally > > unique timestamp for each Put/Get issued from HBase cluster. The reason I > > put it on Zookeeper is that each Put/Get needs to go through it and > unique > > timestamp needs some global centralised facility to do it. But I am > asking > > how practical is this scheme, like anyone used in practice? > > > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > > code path of HBase inside Zookeeper. I know HBase has Coprocessor on > region > > server to let programmer to extend without recompiling HBase itself. Does > > Zk allow such extensibility? Thanks. > > > > Regards > > Yun > > >
Re: How practical is it to add a timestamp oracle on Zookeeper
Have you looked at https://github.com/yahoo/omid/wiki ? The Status Oracle implementation may give you some clue. Cheers On Apr 16, 2013, at 5:14 AM, yun peng wrote: > Hi, All, > I'd like to add a global timestamp oracle on Zookeep to assign globally > unique timestamp for each Put/Get issued from HBase cluster. The reason I > put it on Zookeeper is that each Put/Get needs to go through it and unique > timestamp needs some global centralised facility to do it. But I am asking > how practical is this scheme, like anyone used in practice? > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > code path of HBase inside Zookeeper. I know HBase has Coprocessor on region > server to let programmer to extend without recompiling HBase itself. Does > Zk allow such extensibility? Thanks. > > Regards > Yun
RE: How practical is it to add a timestamp oracle on Zookeeper
Yes, Jean-Marc Spaggiari is right. Performance is the big problem of this approach, though zookeeper can help you implement this. Regards, Jieshan -Original Message- From: Jean-Marc Spaggiari [mailto:jean-m...@spaggiari.org] Sent: Tuesday, April 16, 2013 8:20 PM To: user@hbase.apache.org Subject: Re: How practical is it to add a timestamp oracle on Zookeeper Hi Yun, If I understand you correctly, that mean that each time our are going to do a put or a get you will need to call ZK first? Since ZK has only one master active, that mean that this ZK master will be called for each HBase get/put? You are going to create a bottle neck there. I don't know how many RS you have, but you will certainly hotspot you ZK server. I'm not sure it's a good idea. JM 2013/4/16 yun peng > Hi, All, > I'd like to add a global timestamp oracle on Zookeep to assign globally > unique timestamp for each Put/Get issued from HBase cluster. The reason I > put it on Zookeeper is that each Put/Get needs to go through it and unique > timestamp needs some global centralised facility to do it. But I am asking > how practical is this scheme, like anyone used in practice? > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > code path of HBase inside Zookeeper. I know HBase has Coprocessor on region > server to let programmer to extend without recompiling HBase itself. Does > Zk allow such extensibility? Thanks. > > Regards > Yun >
Re: How practical is it to add a timestamp oracle on Zookeeper
Hi Yun, If I understand you correctly, that mean that each time our are going to do a put or a get you will need to call ZK first? Since ZK has only one master active, that mean that this ZK master will be called for each HBase get/put? You are going to create a bottle neck there. I don't know how many RS you have, but you will certainly hotspot you ZK server. I'm not sure it's a good idea. JM 2013/4/16 yun peng > Hi, All, > I'd like to add a global timestamp oracle on Zookeep to assign globally > unique timestamp for each Put/Get issued from HBase cluster. The reason I > put it on Zookeeper is that each Put/Get needs to go through it and unique > timestamp needs some global centralised facility to do it. But I am asking > how practical is this scheme, like anyone used in practice? > > Also, how difficulty is it to extend Zookeeper, or to inject code to the > code path of HBase inside Zookeeper. I know HBase has Coprocessor on region > server to let programmer to extend without recompiling HBase itself. Does > Zk allow such extensibility? Thanks. > > Regards > Yun >
