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sql server replication : Behaviour of Merge Replication
1) what's the main difference between a push subscription and a pull subscription ? 2) if I have a subscriber node that for many time (4-5 months) is disconnected from publisher, what will it do when it'll be re-connected to the network ? 3) is there a method to force the re-synchronization of DB subscriber in this case ? 4) instead if I have a failure of Publisher server, and I work only with subscribers, what sould I do after the restart of Publisher to load the changes made in subscribers DB ?
Paul, Hilary
thanks for your answers.
answers inline
-- Hilary Cotter Looking for a SQL Server replication book? http://www.nwsu.com/0974973602.html Looking for a FAQ on Indexing Services/SQL FTS http://www.indexserverfaq.com [quoted text, click to view] "Marco" <peska78@tin.it> wrote in message news:1164723024.262636.185820@h54g2000cwb.googlegroups.com... >I want to deepen the function of Merge Replication: > > 1) what's the main difference between a push subscription and a pull > subscription ? With a push the publisher initiates the sync, with a pull the subscriber initiates it. Push is good for a small number of subscribers when you want to centrally manage them. Pull is good for a large number of subscribers but you don't have a central point of management. [quoted text, click to view] > It will probably have expired so you will need to send a new snapshot down. > 2) if I have a subscriber node that for many time (4-5 months) is > disconnected from publisher, what will it do when it'll be re-connected > to the network ? you can upload the subscriber changes before the snapshot is applied. [quoted text, click to view] > Its called a re-initialization. Expand your publication and right click on > 3) is there a method to force the re-synchronization of DB subscriber > in this case ? your subscription and select reinitialize to reinitilize the problem subscriber. [quoted text, click to view] > Nothing. When the subscriber comes back on line it will synchronize changes > 4) instead if I have a failure of Publisher server, and I work only > with subscribers, what sould I do after the restart of Publisher to > load the changes made in subscribers DB ? > which have occurred with the subscribers. If the retention period has passed most of your subscribers will probably have expired which means you will have to reinitialize, run the snapshot agent and then run the merge agents.
Hi Marco - answers inline:
[quoted text, click to view] > 1) what's the main difference between a push subscription and a pull Which box does the work. If I have the choice, I prefer to have the agents > subscription ? centralised and use one set of alerts and notifications. [quoted text, click to view] > The term we use is Reinitialization. sp_reinitmergesubscription and > 2) if I have a subscriber node that for many time (4-5 months) is > disconnected from publisher, what will it do when it'll be re-connected > to the network ? It will error and require reinitialization. > > 3) is there a method to force the re-synchronization of DB subscriber > in this case ? sp_reinitmergepullsubscription can be used. Run the snapshot agent then the merge agent. [quoted text, click to view] > Restore an older version of the publisher's database and synchronize. This > 4) instead if I have a failure of Publisher server, and I work only > with subscribers, what sould I do after the restart of Publisher to > load the changes made in subscribers DB ? > is not foolproof (eg schema changes and download only articles will require some thought) but it generally works. Cheers, Paul Ibison SQL Server MVP, www.replicationanswers.com .
Hi Hilary,
I new in replications and I've just realised that I need Merge replication (after reading the first chapter of your book). So I started looking for information about Merge. But still I've things unclear. For example, I don't know if I should use push or pull subscriber. When you say: [quoted text, click to view] > With a push the publisher initiates the sync, with a pull the subscriber > initiates it. Push is good for a small number of subscribers when you want > to centrally manage them. Pull is good for a large number of subscribers > but you don't have a central point of management. what's a small number of subscribers? Because I've 15 machines to be replicated, where one is a dedicated server, the Central Server. Some tables must be replicated to everywhere (using the Central Server?) and some other tables just replicated to the Central Server (so a filter should be applied?). It's like a star topology. And this goes to another question. What's better, to have the publication in the Central Server and push/pull subscription to the other computers or generate a publication on each server and make the Central Server a subscriber of all? I think that the first option is the best, at least for the tables that must be replicated to everywhere, but I'm not sure for the tables that must be filtered. Thank you, Josep Martínez "Hilary Cotter" <hilary.cotter@gmail.com> escribió en el mensaje news:eNEH1zvEHHA.4132@TK2MSFTNGP04.phx.gbl... [quoted text, click to view] > answers inline > > -- > Hilary Cotter > > Looking for a SQL Server replication book? > http://www.nwsu.com/0974973602.html > > Looking for a FAQ on Indexing Services/SQL FTS > http://www.indexserverfaq.com > > > > "Marco" <peska78@tin.it> wrote in message > news:1164723024.262636.185820@h54g2000cwb.googlegroups.com... >>I want to deepen the function of Merge Replication: >> >> 1) what's the main difference between a push subscription and a pull >> subscription ? > > With a push the publisher initiates the sync, with a pull the subscriber > initiates it. Push is good for a small number of subscribers when you want > to centrally manage them. Pull is good for a large number of subscribers > but you don't have a central point of management. >> >> 2) if I have a subscriber node that for many time (4-5 months) is >> disconnected from publisher, what will it do when it'll be re-connected >> to the network ? > It will probably have expired so you will need to send a new snapshot > down. you can upload the subscriber changes before the snapshot is > applied. >> >> 3) is there a method to force the re-synchronization of DB subscriber >> in this case ? > Its called a re-initialization. Expand your publication and right click on > your subscription and select reinitialize to reinitilize the problem > subscriber. >> >> 4) instead if I have a failure of Publisher server, and I work only >> with subscribers, what sould I do after the restart of Publisher to >> load the changes made in subscribers DB ? >> > Nothing. When the subscriber comes back on line it will synchronize > changes which have occurred with the subscribers. If the retention period > has passed most of your subscribers will probably have expired which means > you will have to reinitialize, run the snapshot agent and then run the > merge agents. >
Hi Josip
There is no hard rule defining small, or the cut off point going from push to pull. I normally use pull for over 10 subscribers. As you have some tables which are only one direction I would use transactional replication. As you have some which are bi-directional I would use merge for those. For the merge publications use central publisher in your head office. For the uni-directional publications it depends on the data flow, if they are going to the central publisher make the branch offices the publishers, ie 14 publishers in the branch office going to the central publisher in the head office. If they are going from the central publisher in the head office to the subscribers branch office use the central publisher in the head office. HTH -- Hilary Cotter Looking for a SQL Server replication book? http://www.nwsu.com/0974973602.html Looking for a FAQ on Indexing Services/SQL FTS http://www.indexserverfaq.com [quoted text, click to view] "Josep" <jmartinez@autec.es> wrote in message news:e4BsFn5FHHA.1912@TK2MSFTNGP03.phx.gbl... > Hi Hilary, > > I new in replications and I've just realised that I need Merge replication > (after reading the first chapter of your book). So I started looking for > information about Merge. But still I've things unclear. For example, I > don't know if I should use push or pull subscriber. When you say: > >> With a push the publisher initiates the sync, with a pull the subscriber >> initiates it. Push is good for a small number of subscribers when you >> want to centrally manage them. Pull is good for a large number of >> subscribers but you don't have a central point of management. > > what's a small number of subscribers? Because I've 15 machines to be > replicated, where one is a dedicated server, the Central Server. Some > tables must be replicated to everywhere (using the Central Server?) and > some other tables just replicated to the Central Server (so a filter > should be applied?). It's like a star topology. > > And this goes to another question. What's better, to have the publication > in the Central Server and push/pull subscription to the other computers or > generate a publication on each server and make the Central Server a > subscriber of all? > I think that the first option is the best, at least for the tables that > must be replicated to everywhere, but I'm not sure for the tables that > must be filtered. > > > Thank you, > > Josep Martínez > > > > "Hilary Cotter" <hilary.cotter@gmail.com> escribió en el mensaje > news:eNEH1zvEHHA.4132@TK2MSFTNGP04.phx.gbl... >> answers inline >> >> -- >> Hilary Cotter >> >> Looking for a SQL Server replication book? >> http://www.nwsu.com/0974973602.html >> >> Looking for a FAQ on Indexing Services/SQL FTS >> http://www.indexserverfaq.com >> >> >> >> "Marco" <peska78@tin.it> wrote in message >> news:1164723024.262636.185820@h54g2000cwb.googlegroups.com... >>>I want to deepen the function of Merge Replication: >>> >>> 1) what's the main difference between a push subscription and a pull >>> subscription ? >> >> With a push the publisher initiates the sync, with a pull the subscriber >> initiates it. Push is good for a small number of subscribers when you >> want to centrally manage them. Pull is good for a large number of >> subscribers but you don't have a central point of management. >>> >>> 2) if I have a subscriber node that for many time (4-5 months) is >>> disconnected from publisher, what will it do when it'll be re-connected >>> to the network ? >> It will probably have expired so you will need to send a new snapshot >> down. you can upload the subscriber changes before the snapshot is >> applied. >>> >>> 3) is there a method to force the re-synchronization of DB subscriber >>> in this case ? >> Its called a re-initialization. Expand your publication and right click >> on your subscription and select reinitialize to reinitilize the problem >> subscriber. >>> >>> 4) instead if I have a failure of Publisher server, and I work only >>> with subscribers, what sould I do after the restart of Publisher to >>> load the changes made in subscribers DB ? >>> >> Nothing. When the subscriber comes back on line it will synchronize >> changes which have occurred with the subscribers. If the retention period >> has passed most of your subscribers will probably have expired which >> means you will have to reinitialize, run the snapshot agent and then run >> the merge agents. >> > >
Thank you for your help!
In the uni-directional publications the data is going from the branch offices to the head office. So the branch office should be the publisher, but the problem is that our customer wants to install MSDE in the branch offices and a SQL Server 2000 Enterprise Edition in the head office. So I can't use the transactional replication :-( So, I'll use a one-way Merge Replication... And some branch offices have a ISDN connection (we can consider that a low connection?) and they should be always online, although they can go offline (maximum a day). These ISDN branches will have a small amount of data replicated to head house. In the case that our client reconsider not to use MSDE, would you still use a Transactional Replication after knowing this? Thanks :-) Josep Martínez "Hilary Cotter" <hilary.cotter@gmail.com> escribió en el mensaje news:%23bU07lFGHHA.2112@TK2MSFTNGP03.phx.gbl... [quoted text, click to view] > Hi Josip > > There is no hard rule defining small, or the cut off point going from push > to pull. I normally use pull for over 10 subscribers. > > As you have some tables which are only one direction I would use > transactional replication. As you have some which are bi-directional I > would use merge for those. > > For the merge publications use central publisher in your head office. For > the uni-directional publications it depends on the data flow, if they are > going to the central publisher make the branch offices the publishers, ie > 14 publishers in the branch office going to the central publisher in the > head office. If they are going from the central publisher in the head > office to the subscribers branch office use the central publisher in the > head office. > > HTH > -- > Hilary Cotter > > Looking for a SQL Server replication book? > http://www.nwsu.com/0974973602.html > > Looking for a FAQ on Indexing Services/SQL FTS > http://www.indexserverfaq.com > > > > "Josep" <jmartinez@autec.es> wrote in message > news:e4BsFn5FHHA.1912@TK2MSFTNGP03.phx.gbl... >> Hi Hilary, >> >> I new in replications and I've just realised that I need Merge >> replication (after reading the first chapter of your book). So I started >> looking for information about Merge. But still I've things unclear. For >> example, I don't know if I should use push or pull subscriber. When you >> say: >> >>> With a push the publisher initiates the sync, with a pull the subscriber >>> initiates it. Push is good for a small number of subscribers when you >>> want to centrally manage them. Pull is good for a large number of >>> subscribers but you don't have a central point of management. >> >> what's a small number of subscribers? Because I've 15 machines to be >> replicated, where one is a dedicated server, the Central Server. Some >> tables must be replicated to everywhere (using the Central Server?) and >> some other tables just replicated to the Central Server (so a filter >> should be applied?). It's like a star topology. >> >> And this goes to another question. What's better, to have the publication >> in the Central Server and push/pull subscription to the other computers >> or generate a publication on each server and make the Central Server a >> subscriber of all? >> I think that the first option is the best, at least for the tables that >> must be replicated to everywhere, but I'm not sure for the tables that >> must be filtered. >> >> >> Thank you, >> >> Josep Martínez >> >> >> >> "Hilary Cotter" <hilary.cotter@gmail.com> escribió en el mensaje >> news:eNEH1zvEHHA.4132@TK2MSFTNGP04.phx.gbl... >>> answers inline >>> >>> -- >>> Hilary Cotter >>> >>> Looking for a SQL Server replication book? >>> http://www.nwsu.com/0974973602.html >>> >>> Looking for a FAQ on Indexing Services/SQL FTS >>> http://www.indexserverfaq.com >>> >>> >>> >>> "Marco" <peska78@tin.it> wrote in message >>> news:1164723024.262636.185820@h54g2000cwb.googlegroups.com... >>>>I want to deepen the function of Merge Replication: >>>> >>>> 1) what's the main difference between a push subscription and a pull >>>> subscription ? >>> >>> With a push the publisher initiates the sync, with a pull the subscriber >>> initiates it. Push is good for a small number of subscribers when you >>> want to centrally manage them. Pull is good for a large number of >>> subscribers but you don't have a central point of management. >>>> >>>> 2) if I have a subscriber node that for many time (4-5 months) is >>>> disconnected from publisher, what will it do when it'll be re-connected >>>> to the network ? >>> It will probably have expired so you will need to send a new snapshot >>> down. you can upload the subscriber changes before the snapshot is >>> applied. >>>> >>>> 3) is there a method to force the re-synchronization of DB subscriber >>>> in this case ? >>> Its called a re-initialization. Expand your publication and right click >>> on your subscription and select reinitialize to reinitilize the problem >>> subscriber. >>>> >>>> 4) instead if I have a failure of Publisher server, and I work only >>>> with subscribers, what sould I do after the restart of Publisher to >>>> load the changes made in subscribers DB ? >>>> >>> Nothing. When the subscriber comes back on line it will synchronize >>> changes which have occurred with the subscribers. If the retention >>> period has passed most of your subscribers will probably have expired >>> which means you will have to reinitialize, run the snapshot agent and >>> then run the merge agents. >>> >> >> > >
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