database-replication | 易学教程

MongoDB balancer timeout with delayed replica

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问题 We have a setup of two mongodb shards. Each shard contains a master, a slave, a 24h slave delay slave and an arbiter. However the balancer fails to migrate any shards waiting for the delayed slave to migrate. I have tried setting _secondaryThrottle to false in the balancer config, but I still have the issue. It seems the migration goes on for a day and then fails (A ton of waiting for slave messages in the logs). Eventually it gives up and starts a new migration. The message says waiting for

Logical decoding on a standby node

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问题 PostgreSQL 9.4 introduced Logical Decoding: http://www.postgresql.org/docs/9.4/static/logicaldecoding.html It also has Cascade Streaming Replication: http://www.postgresql.org/docs/9.4/static/warm-standby.html#CASCADING-REPLICATION Logical Decoding seems to be based on Streaming Replication. However a PostgreSQL server will refuse to start a Logical replication slot on a hot standby. It will only allow Logical Decoding on the master node. What prevents a hot standby node to replicate itself

Rails Octopus Gem - Master-Slave Replication connection behaviour when slave is down

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问题 I'm testing this great gem Octopus with Rails 4.0.2 in development. I created a Slave db and configured octopus as follows (config>shards.yml) : octopus: environments: - development replicated: true fully_replicated: true verify_connection: true development: slave1: host: 192.168.1.12 adapter: mysql2 username: slave_reader password: my_password database: my_server_development reconnect: true It works very nice, reading from the Slave and writing to the Master, however if My Slave server is

What is syncobj in SQL Server

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问题 When I run this script to search particular text in sys.columns and I get a lot of "dbo.syncobj_0x3934443438443332" like rows. SELECT c.name, s.name + '.' + o.name FROM sys.columns c INNER JOIN sys.objects o ON c.object_id=o.object_id INNER JOIN sys.schemas s ON o.schema_id=s.schema_id WHERE c.name LIKE '%text%' If I get it right, they are replication objects. Is it so? Can i just throw them away from my query just like o.name NOT LIKE '%syncobj%' or there's another way? Thank you. 回答1: I've

Best practices for daily MySQL (partial and filtered) replication?

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I have a reasonable large database with > 40 tables. I only need to replicated a few tables (+/- 5). And each tables is also filtered. I'm looking for some best practices for replicating this data (daily is enough), where i can select just a few tables and included some WHERE clauses for each table. I'm thinking of starting mysqldump for each table (with a where clause) and make for each table a separate .sql file. I then can then truncate all tables (all data is daily overwritten) on the destination db, and run mysql for importing each table separate. Example: # dump each table mysqldump -u

Can I set up a filtered, star-pattern database replication?

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问题 We have a client that needs to set up N local databases, each one containing one site's data, and then have a master corporate database containing the union of all N databases. Changes in an individual site database need to be propagated to the master database, and changes in the master database need to be propagated to the appropriate individual site database. We've been using MySQL replication for a client that needs two databases that are kept simultaneously up to date. That's a

CouchDB replication strategy with dynamic groups of users

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问题 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

Is it possible to control order of replication?

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问题 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 documents come first. I need to ensure that the documents with highest priority are definitely of the latest version, and I can ignore documents in the end of list. SORTING, not FILTERING If it is not possible, what solution could be? Resource I have

MongoDB Multiple Masters in ReplicaSet

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问题 I've got a question concerning multiple masters in a replicaSet with MongoDB. I have the following layout: Server A --> with MongoDB & several applications Server B --> with MongoDB & several applications Both instances of MongoDB are organised in the same replica Set (Server A as Primary, Server B as Secondary). But now there is the problem. Both databases should contain data from the applications on the server. Is it possible to deploy a replica Set with two masters so that the data from

How to implement real-time replication of MongoDB (or CouchDB) to many remote clients

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I'm considering how to design a mechanism for replicating a (potentially large) MongoDB or other NoSQL (CouchDB, etc) database to dozens of clients at once. The clients would function like a replica set, but the replication would be one-way and the remote clients would belong to other parties. Specifically, I am looking for the following features: real-time : changes to the master database should be pushed out to the clients as quickly as possible replication to new clients : a new client must be able to connect, automatically sync the majority of existing data, then receive real-time updates.