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Questions tagged [database-replication]

Database replication is used to ensure consistency between redundant databases and to improve reliability and increase fault-tolerance. The replication process commonly involves continuously duplicating a "master" database to one or more additional "slave" databases.

Database replication can be used on many database management systems, usually with a master/slave relationship between the original and the copies. The master logs the updates, which then ripple through to the slaves. The slave outputs a message stating that it has received the update successfully, thus allowing the sending (and potentially re-sending until successfully applied) of subsequent updates.

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MongoDB replica sets with odd and even number of members

I've noticed a few peculiarities about MongoDB replica sets. In a 3-node replSet, if the PRIMARY goes down, I see that the set elects a new PRIMARY and everything is fine without experiencing any downtime. But if another member goes down (2 total…
CraexIt
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Enabling authentication on already running mongoDb replicaset

I'm using Ubuntu 14.04, mongodb 2.6.3(current secondary) and 2.6.4(current primary). I'm trying to enable authentication on an already running mongodb replicaset with 3 nodes of which 1 is arbiter.But I was unable to do that. Is it not possible to…
Shobhit Mishra
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MySQL master slave replication from first binlog position

I have a couple of live databases that need migrating over to a new server. These are large databases constantly in use. I want to setup replication with a slave on the new server and begin porting data across. However, I'd like to try and avoid…
James
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mysql master-master data replication consistency

As we know mysql do replication asynchronously. I heard that I need some extra plugins to do synchronous replication. So let us Consider the situation of asynchronous replication: The master writes events to its binary log but does not know whether…
huican
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Setting up MySQL master - master replication

I currently have one master server and want to add another master server for fail over. On the primary server I've added the following to "my.ini" server-id = 1 replicate-same-server-id = 0 auto-increment-increment = 2 auto-increment-offset =…
gijs007
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How to add new server in replica set in production

I am new to mongodb replica set. According to Replic Set Ref this should be connection string in my application to connect to mongodb mongodb://db1.example.net,db2.example.net,db3.example.net:2500/?replicaSet=test Suppose this is production replica…
Watt
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AWS DynamoDB read after write consistency - how does it work theoretically?

Most of the nosql solution only use eventually consistency, and given that DynamoDB replicate the data into three datacenter, how does read after write consistency is being maintained? What would be generic approach to this kind of problem? I think…
Howard
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NoSQL databases in offline mode and forward compatibility

After doing some research, it seems that when people ask about schema migration in CouchDB, they get quickly rebutted that the concept is not exactly compatible with NoSQL ideology. I understand how NoSQL is meant to be schema-less and it feels…
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ActiveRecord counter_cache giving stale count with multi_db gem

I'm using the multi-db gem with Slony-I replication on PostgreSQL in a Rails app. This mostly works perfectly, but there is a bit of a replication lag in certain cases. One of the cases involves an ActiveRecord counter_cache. For clarity, assume the…
Christopher Foy
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Is it possible to control order of replication?

I have a huge master CouchDB database and slave read-only CouchDB database, that synchronizes with master database. Because rate of changes is quick, and channel between servers is slow and unstable, I want to set order/priority to define what…
Paul Verest
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Can SymmetricDS be used for iOS

SymmetricDS has an android sqlite implementation that is awesome. I was wondering if i could do the same with iOS . I couldn't find anything on their website or on google (basic search spent around an hour). Also, I was hoping someone could tell me…
SandeepRM
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Life-copies for devel-team in MongoDb

Q: Which is the best architecture for life-copies for testing and development? Current setup: We have two amazon/EC2 mongod servers like this: Machine A: A production database (on an amazon/EC2 server) (name it ‘PROD’) Other databases…
Marina Planells
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How to determine whether a table is used to store materialized view logs?

I have table with created on it materialized view log: create table T1(A number primary key); create materialized view log on T1 with primary key; Oracle additionally creates two tables for materialized view logs: select TABLE_NAME from…
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DBMS with offline replicas + advanced security + queries

We're currently evaluating DBMS that are able to handle offline replicas (as in, replicas are allowed to stay offline for long amounts of time). CouchDB would be a prime candidate, however there are lots of drawbacks for our usecase. Some of these…
Michel Müller
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SQL Server Bi-Directional Transactional Replication - Is it a good use-case?

We're having a problem with scaling out with SQL server. This is largely because of a few reasons: 1) poorly designed data structures, 2) heavy lifting and business/processing logic is all done in T-SQL. This was verified by a Microsoft SQL guy…
Josh Barker
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