Question

Lets say we have MySQL server A, where we need to create a ‘copy’ of table, which is situated on server B.

We don’t have federated enabled. Reseting server A would cause much trouble and I believe, we cannot enable federated without reseting. I also believe that it is not enough to enable it on the B server (correct me if I’m wrong in anything)

What other solutions do we have? Is there something enabled by default in mysql server? Any ideas?

Answer 1

• You need federated enabled just on server B
• You can access a view on A by making a federated table on B
• You can do INSERT UPDATE DELETE on federated table
• If you need read-only access you can limit the user privileges

BUT! You can’t do any aggregate func. on a view which will be federated (ex. COUNT(), MAX(), UNION…) (you can, however it will lag)

• Remember to set the KEY’s on the federated table you are creating. (or it will lag horr.)
• Remember to use ALGORITHM=MERGE on views
• Remember to grant acces to USERNAME(from connection string) on server A

example of a federated table on server B:

delimiter $$
CREATE TABLE `schemaName`.`tableName`(
    `keyName` VARCHAR(10) NOT NULL,
    `key2Name` DATE DEFAULT '2012-01-01',
    KEY `keyName` (`keyName`) 
)
ENGINE=FEDERATED
DEFAULT CHARSET=utf8
CONNECTION='mysql://USERNAME:PASSWORD@IPADDRESS:PORTNUMBER/baseSchema/baseTable'
$$

And the view on server A:

CREATE
    ALGORITHM = MERGE
    DEFINER = `ANOTHERUSERNAME`@`%`
    SQL SECURITY DEFINER
VIEW `baseSchema`.`baseTable` AS
    SELECT
        ... AS `keyName`,
        ... AS `key2Name`
    FROM
        ...