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Questions tagged [replication]

The use of redundant resources to improve reliability, fault-tolerance, or performance.

Replication is the process of sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility.

It could be data replication if the same data is stored on multiple storage devices, or computation replication if the same computing task is executed many times.

A computational task is typically replicated in space, i.e. executed on separate devices, or it could be replicated in time, if it is executed repeatedly on a single device.

The access to a replicated entity is typically uniform with access to a single, non-replicated entity. The replication itself should be transparent to an external user. Also, in a failure scenario, a failover of replicas is hidden as much as possible.

More info on Wikipedia

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Why do my MongoDB logs fill up with "getmore local.oplog.rs"?

This is repeated over and over again in my MongoDB logs. Some notes: MongoDB 1.8.1 on Ubuntu 11.04 Primary in a replica set 64gb disk 5gb RAM new Date(5610408224193773570) is always the same verbose = true is commented out in the config file Could…
Seamus Abshere
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What are the use cases for a Vector Clock versus a Version Vector?

I have been having trouble finding an example of what use cases are suitable for Vector Clocks and Version Vectors, and how they might differ. I understand that they largely work in the same way, with Vector Clocks using receive and send functions,…
arabellel
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Ehcache / Hibernate and RMI replication with large number of entities

I'm currently investigating how to use the RMI distribution option in ehcache. I've configured properly ehcache.xml and replication seems to work fine. However I've 2 questions: -> It seems ehcache/ hibernate creates 1 cache per Entity. This is…
Lionel Touati
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Tomcat: Store session in database

I am searching for a way to avoid in-memory session replication/clustering and store the session in a database. Using Tomcat's JDBCStore is useless at this point, because it only stores inactive sessions in the database to save the servers…
Fabe
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Create Oracle Materialized View to be refreshed every 5 minute Using materialized view log

I'm Trying to create Materialized View which will be updated every 5 minute automatically, I need update based on Mview log table. I have created Materialized view log on TABLE1 TABLE1.SQL Script CREATE MATERIALIZED VIEW LOG ON TABLE1; --…
JiboOne
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Cassandra Data Replication problem

I have a 2 node cassandra cluster with a replication factor of 2 and AutoBootStrap=true. Everything is good during startup and both nodes see each other. Let us call these nodes A and B. Add a set of keys and columns (lets call this set K1) to…
Rajan
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postgres streaming replication - slave only index

We have successfully deployed Postgres 9.3 with streaming replication (WAL replication). We currently have 2 slaves, the second slave being a cascaded slave from the first slave. Both slaves are hot-standby's with active read-only connections in…
Scott Johnston
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mongoDB replication+sharding on 2 servers reasonable?

Consider the following setup: There a 2 physical servers which are set up as a regular mongodb replication set (including an arbiter process, so automatic failover will work correctly). now, as far as i understand, most actual work will be done on…
MGriesbach
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MySQL replication: temporarily prevent specific SQL statements replicating to the slaves?

I want to connect and execute one (or sometimes several) SQL statements, and NOT have those replicated to the slaves. I have no replicate-do or replicate-ignore configs, so I can't use some non-replicated database to send the commands from. And I…
Nautical
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MongoDB 3.0 write lock on oplog collection in replica mode

In replica mode each write operation to any collection in any DB, also writes to the oplog collection. Now, when writing to multiple DBs in parallel, all these write operations also write to the oplog. My question: do these write operations require…
Baruch Oxman
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SQL Server equivalent of MySQL multi-master replication?

Is there an MSSQL equivalent of MySQL's multi-master replication? If so, is it available in SQL Express 2008? I've also seen it referred to as two node circular replication. Basically, I have an in-office database that I want to be perfectly…
please delete me
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Element-wise Matrix Replication in MATLAB

I have a 3 dimensional matrix. I want to replicate the matrix of size 8x2x9 to a specified number of times in the third dimension given by a vector say [3, 2, 1, 1, 5, 4, 2, 2, 1] so that the resultant matrix is of size 8x2x21. Is there any built-in…
Santhan Salai
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SQL Server 2005 Replication and different indexes on the subscriber

We have SQL Server database setup. We are setting up a replication scenarios where we have one publisher and on subscriber. The subscriber will be used as a reporting platform so that we can run all the BI queries that we need and have to hit the…
Kinlan
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How can I filter data during replication and give user only his own documents?

I need to sync server data from CouchDB and PouchDB on client side. Every user has his own data. When he is online this data is being updated. How can I filter data during replication and give user only his own documents? This is security issue for…
Oleh Herych
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Why use GTIDs in MySQL replication?

When it comes to database replication, what is the use of global transaction identifiers? Why do we need it to prevent concurrency across the servers? How is that prevention achieved exactly? I tried to read the documentation…
Chong Lip Phang
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