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Multiple MySQL Date Replication

0 votes
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I have been asked to set up multiple database replication which I have done before for simple cases however there are some nuances with this instance that add some complexity and I'd like to hear your collective expertise on this proposed scenario:-

1) Single master database
2) n (probably 3 to start with) number of slave databases
3) All but 5 tables (123 tables in total) are to be replicated from the master to all the slaves
4) 3 tables from the slaves are to be replicated back to the master

It is mainly item 4) that concerns me - the primary ID's are almost certain to collide unless I seed the auto increment ID to partition the IDs into separate ranges or does MySQL handle this issue?
There are some foreign keys on one of the 3 slave to master tables but they are pointing at some extremely static tables that are very unlikely to change. Is the above a feasible implementation...?

posted Jul 24, 2013 by anonymous

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1 Answer

+1 vote
4) 3 tables from the slaves are to be replicated back to the master

NO.

However, consider Percona XtraDb Cluster or MariaDB+Galera. They allow multiple writable masters. But they won't let you be so selective about tables not being replicated. Here are the gotchas for Galera usage:
http://mysql.rjweb.org/doc.php/galera
If you can live with them (plus replicating everything), it may be best for you.

answer Jul 24, 2013 by anonymous
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+1 vote

We have replication set-up, where we cater to huge amounts of data. Since quite some time, we have been facing issues wherein the slave lags behind master quite a lot.

So, yesterday we were able to setup parallel replication, by incorporating the following changes ::

a) To begin with, partitioned some tables into dedicated databases.

b) Set up the "slave-parallel-workers" parameter.

The above seems to work functionally fine, but we have one doubt/query about the scalability of this solution.

First, I will jot down the flow as far as I understand (please correct if wrong) ::

"Even in parallel-replication scenario, the master writes all the binlog (combined for all databases) in just one file, which then gets passed onto the slave as single-file itself. Thereafter, all the replication commands (combined for all databases) are written sequentially onto one slave-relay file.

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So far, so good. However, what would happen if the slave-relay file contains the following ::

db1-statement-1 (short-running)
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We will be grateful if someone could please clarify, as to how the above statements will be managed among the Manager and the Worker-Threads (let's say there is just one worker-thread-per-db) ?

In particular, does the Manager thread creates internal slave-relay-log-files, one for per database-statements?

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