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4

If you want real HA ("High Availability"), you need 3 nodes in 3 separate locations. When one machine goes down, the rest of the nodes vote and see that they are in the majority. They see 2 out of 3, so they declare themselves to be the cluster and their sibling to be out of the cluster. If the dead machine comes back online, the majority chatter with the ...


3

This is a common requirement. Transactional Replication is typically used to off-load reporting to another server/instance, which can be near real-time in a best case scenario. One of the benefits of Transactional Replication is you can place different indexes on the subscriber(s) to optimize reporting. Another benefit is that you can choose to replicate ...


3

Yes, this still holds true. It is covered in Upgrade Replicated Databases in the SQL Server 2014 documentation.


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DDL can still replicate with row-based replication From the MySQL Documentation for binlog-do-db For example, DDL statements such as CREATE TABLE and ALTER TABLE are always logged as statements, without regard to the logging format in effect Since CREATE INDEX is mapped to ALTER TABLE, CREATE INDEX will work just fine.


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Yes, it is very possible. As the Documentation says, you should have a minimum of three nodes in a Percona XtraDB Cluster. You only need one node out of the three nodes. Make sure all nodes in the PXC have unique server_ids. Make sure the Master you are replicating from has a unique server_id from the PXC nodes Make sure the master and every PXC node is ...


1

There are cases in Merge Replication when parent and child rows can be processed out of order on synchronization resulting in constraint violations and conflicts. To understand how and why this can occur and how it may apply to your specific scenario, I recommend reading through: How to understand Merge Replication article processing order Merge Article ...


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I am adding an additional answer because Giovanni's one is completely right, but it only defines why scaling, how to do HA on the master and on the slaves, and how to split read queries among the slaves from an architectural point of view. I think OP question was more about how to do the read-write split itself. Then answer depends on the software stack ...


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A good solution is to define two datasources for the applications. One datasource pointing to master is for writing. One datasouce pointing to slave node is for reading. The applications must be aware that data can be delayed with respect to the master. There are applications that could tolerate a slight delay on data, and other applications that must be ...


1

1) Yes 2) it's not going to be a problem but of course it depends on the problem itself. Lets use the term - incident. Problem is already a problem by definition. Solve incidents, analyze the cause , prevent the problem!!! ;) 3) in case of an error, try to think what caused it. Nothing to worry about specifically in my opinion Try to strictly separate ...


1

"Is it possible to do so? The trigger will insert some rows into a unique table that exists only on the slave." yes, you can A lot of warehousing architectures are based on the slave only. The title of your question is wrong. Change replica DB with SLAVE ONLY


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In earlier versions of MySQL, you would run this on the Master STOP SLAVE; CHANGE MASTER TO master_host = ''; and restart mysqld. For MySQL 5.5/5.6, you would run this on the Master STOP SLAVE; RESET SLAVE ALL; MySQL restart not required For more details on this, please read Disconnecting a replication slave is easier with MySQL 5.5+ (RESET SLAVE vs. ...


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PXC (and other Galera solutions) require one network hop at COMMIT time. If your application can combine writes into a single transaction, that will help at some level. However, still each COMMIT will take 300ms (or whatever it is). Regular MySQL can do Master-Master and have both writable. That replication is asynchronous. However, there are a number ...


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After you ran RESET SLAVE; make sure there is no slave status. Run this SHOW SLAVE STATUS\G If there is any information still being presented, you need to run this CHANGE MASTER TO master_host = ''; Then, go run SHOW SLAVE STATUS\G You should get nothing and master.info should be gone. From the MySQL 5.1 Documentation If any startup options ...


1

Assuming you are running transaction replication. This is how it works in your scenario When initial records are inserted with replicated column value as 'N' on publisher no records will be replicated to subscriber. Once you update the some of the records with replicated column value as 'Y' based on your logic on publisher only those 'Y' records will ...


1

Just to clarify what I mean by having an an update to date copy we don't mind if the database is only updated or synchronized once a day. Depending on the database size, I would use backup with compression and restore. You can easily automate this process. Just take full backup with compression once every night, upload it to FTP (probably secure) and ...


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There are no hard-and-fast rules for such Slaves. Let's look at two scenarios SCENARIO #1 Some standardize all DB Servers to have the same configuration. The rationale behind this is promote a Slave to a Master should have to fail over to it. SCENARIO #2 A scaled down Slave being used as a data backup. No reads from that Slave. COMPARISON OF SLAVES For ...


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One reason could be that your oplog is too small. On the master: db.getReplicationInfo() If timeDiffHours is shorter than the time that your initial sync takes, then the initial sync will fail and start again... Resizing the oplog is quite easy, if this is indeed your problem. The documentation is here: ...


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From this http://slony.info/documentation/2.0/administration.html It's a bit diff.. as to the order and which/where to issue the sync. Not sure which is preferred or best. Ive been doing without sync event and not 100% . LOCK SET(id=1,ORIGIN=1); MOVE SET(ID=1,OLD ORIGIN=1, NEW ORIGIN=3); SYNC(ID=3); WAIT FOR(ORIGIN=1, CONFIRMED=ALL,WAIT ON=1);



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