Re: Multimaster

<div class="moz-cite-prefix">Il 14/04/2016 07:45, Craig Ringer ha scritto:<br /></div><blockquote
cite="mid:CAMsr+YHA-ijT0Cq1UTy=YNXyEf7WcfzHAXQXxdOCqwu4M=uD+g@mail.gmail.com"type="cite"><div dir="ltr"><div
class="gmail_extra"><divclass="gmail_quote">On 2 April 2016 at 02:15, Moreno Andreo <span dir="ltr"><<a
href="mailto:moreno.andreo@evolu-s.it"moz-do-not-send="true" target="_blank">moreno.andreo@evolu-s.it</a>></span>
wrote:<br/><div> </div><blockquote class="gmail_quote" style="margin:0 0 0             .8ex;border-left:1px #ccc
solid;padding-left:1ex">Actually we have to improve what our replicator is doing: it's only replicating the single
user'sdatabase. The improvement should that we can put it on the "server" (in some cases there are groups of users
sharinga dedicated server) and, given a configuration of what and how to replicate, it should replicate more than one
DBa time.<br /></blockquote><div><br /></div><div>That's a layer on top as far as pglogical is concerned. It's only
interestedin a single database at a time.</div><div><br /></div><div>The same is true of
BDR.</div></div></div></div></blockquote>I'll try to explain.<br /> We have a "cloud server" which contains all users
DBsand to which all users connect to get replication and.<br /> Some users have more than one work site, i.e. in one
they'realone (and the PostgreSQL server is on their own work PC) and in another they're teamed up and they have a
dedicatedserver (and everyone can write on teammates' databases).<br /> In the first case it's easy: the only database
isreplicated with the corresponding one on the cloud server. Straightforward.<br /> At the current state, in the team
case,replication occurs only when the user connects to application, so if there's a user going to a particular site
say,only once a week, in the remaining days all data input by team mates won't be replicated, and the user won't be
awareon what's been done until he replicates again...<br /> So we are trying to have a process, running on the server,
thatchecks for any database to be replicated and performs the action on all of these.<br /><br /> Case 1<br /> Local   
                    Remote<br /> [User1:DB1]    -->    [DB1]<br /><br /> Case 2<br /> [User1:DB1]    -->   
[DB1]<br/> [User2:DB2]    -->    [DB2]<br /> ...<br /> [UserN:DBn]   -->    [DBn]<br /><br /><blockquote
cite="mid:CAMsr+YHA-ijT0Cq1UTy=YNXyEf7WcfzHAXQXxdOCqwu4M=uD+g@mail.gmail.com"type="cite"><div dir="ltr"><div
class="gmail_extra"><divclass="gmail_quote"><div><br /></div><div>A tool that automatically configures newly found
databasesto be replicated should be pretty trivial to write, though.</div></div></div></div></blockquote> All databases
thathave to be replicated have a flag in the app configuration, and the replication config is set up, for each database
andeach site, when the first synchronization is made, so we could spawn a process per database and replicate.<br /> Not
tomention we should be able, if necessary, to exclude one or more tables from the replication.<br /><blockquote
cite="mid:CAMsr+YHA-ijT0Cq1UTy=YNXyEf7WcfzHAXQXxdOCqwu4M=uD+g@mail.gmail.com"type="cite"><div dir="ltr"><div
class="gmail_extra"><divclass="gmail_quote"><div> </div><blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px#ccc solid;padding-left:1ex"> We were beginning to "translate" (and then improve) this program in
c#,when I bumped into articles pointing to BDR, and I started taking a look. But it seems that is good to replicahe
wholeservers, and still hasn't the granularity we need.</blockquote><div><br /></div><div>Huh?</div><div><br
/></div><div>BDRis configured database-by-database. The only exception is with bdr_init_copy, for initial setup using
binarybase backups; in that case all databases are copied.</div></div></div></div></blockquote> Hmmm... it seems I
misunderstoodsomething......<br /><blockquote
cite="mid:CAMsr+YHA-ijT0Cq1UTy=YNXyEf7WcfzHAXQXxdOCqwu4M=uD+g@mail.gmail.com"type="cite"><div dir="ltr"><div
class="gmail_extra"><divclass="gmail_quote"><div><br /></div><div>It sounds like you actually *want* to replicate all
databasesat once. Presumably the reason you're not just using physical streaming replication for that  is that
differenthosts have a different set of writeable databases? E.g.</div><div><br /></div><div>[Node A]   [Node
B]</div><div>[DB-1]  ->  [DB-1]</div><div>[DB-2]   ->  [DB-2]</div><div>[DB-3]   <-  [DB-3]</div><div>[DB-4]  
<- [DB-4]</div><div><br /></div><div>so each DB is written from only one node at a time, but both nodes have
writeableDBs. Right?</div></div></div></div></blockquote> Yes, I tried to explain this in the first part of the
message.<br/><br /> Thanks<br /> Moreno<br /><blockquote
cite="mid:CAMsr+YHA-ijT0Cq1UTy=YNXyEf7WcfzHAXQXxdOCqwu4M=uD+g@mail.gmail.com"type="cite"><div dir="ltr"><div
class="gmail_extra"><brclear="all" /><div><br /></div> -- <br /><div class="gmail_signature"><div dir="ltr"><div><div
dir="ltr"> CraigRinger                   <a href="http://www.2ndQuadrant.com/" moz-do-not-send="true"
target="_blank"><aclass="moz-txt-link-freetext"
href="http://www.2ndQuadrant.com/">http://www.2ndQuadrant.com/</a></a><br/>  PostgreSQL Development, 24x7 Support,
Training& Services<br /></div></div></div></div></div></div></blockquote><br />