Обсуждение: BDR
Sorry if this question was asked before. As I understand currently BDR does not support the replicating nodes to run different major versions, like 9.4 <-> 9.5. Is this in the works? thanks
Sorry if this question was asked before. As I understand currently
BDR does not support the replicating nodes to run different major
versions, like
9.4 <-> 9.5.
Is this in the works?
This seems relevant...
But you question seems vague since BDR is a concept for which many implementations exist.
David J.
> This seems relevant... > > http://bdr-project.org/docs/stable/logical-vs-physical.html thanks. very useful.
On 11 June 2016 at 02:26, David G. Johnston <david.g.johnston@gmail.com> wrote:
Sorry if this question was asked before. As I understand currently
BDR does not support the replicating nodes to run different major
versions, like
9.4 <-> 9.5.
Is this in the works?This seems relevant...But you question seems vague since BDR is a concept for which many implementations exist.
I think they're specifically referring to 2ndQ's BDR project here, rather than bi-directional logical replication general.
On 11 June 2016 at 02:12, Rakesh Kumar <rakeshkumar464a3@gmail.com> wrote:
Sorry if this question was asked before. As I understand currently
BDR does not support the replicating nodes to run different major
versions, like
9.4 <-> 9.5.
Is this in the works?
Not with BDR between 9.4 and 9.5, no, as there will not be a 9.5 version of BDR. It'll be skipping straight to 9.6.
pglogical, a simplified and streamlined version of the logical replication facilities used in BDR, can replicate from 9.4 to 9.5 (or to/from any other combo of verisons 9.4+). It doesn't support multimaster or DDL replication like BDR does, though.
You can also look into Londiste and Slony-I.
http://bdr-project.org/docs/next/logical-vs-physical.html "It (BDR) has significant advantages - and some disadvantages - when compared to PostgreSQL's older physical (block-based) streaming or archive-based replication with warm or hot standby" What exactly is block based? Changes are recorded in the redo log, right? Does that mean that in streaming replication, from redo log the server applies changes at the block level of the data-file. That would also mean that at any time, both primary and standby would be exactly same, block by block.
Block based replication is the replication mechanism postgres incorporates natively. It's, in brief, sending all the file-levelchanges to all the slaves, so the data folder is always the same. It's like having a replicated folder, not includinglogs and some other things. The disadvantage of block level replication, according to BDR, it that, when you have an open transaction, all DML is writtento disk, even when the transaction is not committed. In a large transaction, all the date would be send to the slaves,even when, at the end, the transaction is rolled back. With BDR, the transaction is sent to the other masters onlyonce it's committed. Of course, this can be a problem in both cases, depending on your environment. With block level replication, you can getunnecessary traffic for transactions that would be finally rolled back(in contrast with BDR, which will send the wholetransaction once it's committed); on BDR, you will get traffic peaks for some large transactions, as the whole transactionis sent once it's committed(in contrast to block level replication, which would send changes as they are beingexecuted). The later can also cause some delay, depending on the connection between the servers: Regards, Alvaro Aguayo Jefe de Operaciones Open Comb Systems E.I.R.L. Oficina: (+51-1) 3377813 | RPM: #034252 / (+51) 995540103 | RPC: (+51) 954183248 Website: www.ocs.pe ----- Original Message ----- From: "Rakesh Kumar" <rakeshkumar464a3@gmail.com> Cc: "PostgreSql-general" <pgsql-general@postgresql.org> Sent: Monday, 13 June, 2016 07:13:09 Subject: Re: [GENERAL] BDR http://bdr-project.org/docs/next/logical-vs-physical.html "It (BDR) has significant advantages - and some disadvantages - when compared to PostgreSQL's older physical (block-based) streaming or archive-based replication with warm or hot standby" What exactly is block based? Changes are recorded in the redo log, right? Does that mean that in streaming replication, from redo log the server applies changes at the block level of the data-file. That would also mean that at any time, both primary and standby would be exactly same, block by block. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general