database-replication

This is the situation: We have a series of users who share some documents. The documents they can share might change throughout the day, so can the documents themselves (changes and deletions). The users can change some information on the documents. E.g. Users | Documents A | X A | Y A | Z B | X B | Z C | Y Possible groups: A+C, A+B The server on CouchDB is a replica of a SQL Server DB with this data, an ETL takes care of managing changes on CouchDB. However, the CouchDB database is replicated on each user phone via PouchDB. The goal: To replicate changes and deletions accordingly. What we've

Want to set up mysql master-slave replications in rails app. Are there plugins/db adapters available for Rails 3? Does the Masochism plugin work properly with rails 3? Try Octopus, which supports both rails3 and rails2.3: https://github.com/tchandy/octopus Masochism, DbCharmer, data_fabric et al will probably never be updated for Rails3 since so many ActiveRecord internals have drastically changed. data_fabric also now claims support for Rails 3.0.7 https://github.com/mperham/data_fabric and seamless_database_pool has been patched to support Rails 3 (but looks like it hasn't been updated in

I have a requirement where i have create replication between two tables with different names and which have different column names. Is it possible to create such replication. server A server B ---------- ---------- Table : Test Table : SUBS -------------- --------------- columns A,B,C Columns D,E,F,G,H I want to configure replication so that column A data is replicated to column D, column B data is replicated to column E, column C data is replicated to column F Apparently, the answer is: "When you define the article, you'll have to set the @vertical_partition parameter to true and then add the

In a microservice architecture, we usually have two ways to communicate 2 microservices. Let’s say service A needs to get information from service B. The first option is an remote call, usually synchronous over HTTPS, so service A query an API hosted by service B. The second option is adopting an event-driven architecture, where the state of service B can be published and consumed by service A in asynchronous way. Using this model, the service A can update its own database with the information from the service B’s events and all queries are made locally in this database. This approach has the

I am trying to find out, what the difference between optimistic concurrency control (OCC) and multi version concurrency control (MVCC) is? So far I know that both is based on version checking for updates. In OCC, I read about transactions that acquire no locks for reading access, only for the later update which will fail if in between the version was incremented and version checking fails. In this case the transaction will be rolled back. In MVCC, it is basically the same, or not? Where is the difference? I think they are sometimes used interchangeably, and if the transaction only involves one

To set up the replica set, I've run in 3 separate terminal tabs: $ sudo mongod --replSet rs0 --dbpath /data/mining --port 27017 $ sudo mongod --replSet rs0 --dbpath /data/mining2 --port 27018 $ sudo mongod --replSet rs0 --dbpath /data/mining3 --port 27019 Then, I configured replication in the Mongo shell and verified that it worked: > var rsconf = { _id: "rs0", members: [ { _id: 0, host: 'localhost:27017' }, { _id: 1, host: 'localhost:27018' }, { _id: 2, host: 'localhost:27019' } ] }; > rs.initiate(rsconf); { "info": "Config now saved locally. Should come online in about a minute.", "ok": 1 }