How do you copy a table from MySqlServer_A to MySqlServer_B?
I tend to shy away from the FEDERATED storage engine for three(3) reasons:


It only supports MyISAM
DDL performed on the source table requires manually changing the FEDERATED table design on external services.
Bulk operations against a FEDERATED table can become an instant mightmare !!!


What to do ???

One possibility is to use mysqldump and merge them

EXAMPLE
Assuming all tables have identical structures
Assuming all tables are not using auto_increment IDs
Assuming all tables are InnoDB

On the server that will combine the three tables, create four(4) import databases (one time operation):

CREATE DATABASE ImportDB1;
CREATE DATABASE ImportDB2;
CREATE DATABASE ImportDB3;
CREATE DATABASE ImportCombined;


Import Process Goes Something Like This

mysqldump the three(3) tables

mysqldump -hHOSTIP1 -Pportnumber1 -u... -p... dbname tbname &gt; /root/ImportTable1.sql &amp;
mysqldump -hHOSTIP2 -Pportnumber2 -u... -p... dbname tbname &gt; /root/ImportTable2.sql &amp;
mysqldump -hHOSTIP3 -Pportnumber3 -u... -p... dbname tbname &gt; /root/ImportTable3.sql &amp;
wait


Load the mysqldumps into the separate import databases in parallel:

mysql -hHOSTIP4 -u... -p... -A -DImportDB1 &lt; /root/ImportTable1.sql &amp;
mysql -hHOSTIP4 -u... -p... -A -DImportDB2 &lt; /root/ImportTable2.sql &amp;
mysql -hHOSTIP4 -u... -p... -A -DImportDB3 &lt; /root/ImportTable3.sql &amp;
wait
rm -f /root/ImportTable1.sql &amp;
rm -f /root/ImportTable2.sql &amp;
rm -f /root/ImportTable3.sql &amp;
wait


Next, combine the data.

DROP TABLE IF EXISTS ImportCombined.tbname;
CREATE TABLE ImportCombined.tbname LIKE ImportDB1.tbname;
ALTER TABLE ImportCombined.tbname DISABLE KEYS;
INSERT INTO ImportCombined.tbname SELECT * FROM ImportDB1.tbname;
INSERT INTO ImportCombined.tbname SELECT * FROM ImportDB2.tbname;
INSERT INTO ImportCombined.tbname SELECT * FROM ImportDB3.tbname;
ALTER TABLE ImportCombined.tbname ENABLE KEYS;
ALTER TABLE ImportCombined.tbname ENABLE KEYS;


Now, perform the task you already have in place against the ImportCombined.tbname table.

"You fill in these steps"

Then, when the table is ready to be exported, mysqldump it and copy 2 times:

mysqldump -hHOSTIP4 -Pportnumber4 -u... -p... ImportCombined tbname &gt; /root/ExportTable1.sql
cp /root/ExportTable1.sql /root/ExportTable2.sql &amp;
cp /root/ExportTable1.sql /root/ExportTable3.sql &amp;
mysql -hHOSTIP1 -Pportnumber1 -u... -p... -A -Ddbname &lt; /root/ExportTable1.sql &amp;
mysql -hHOSTIP2 -Pportnumber2 -u... -p... -A -Ddbname &lt; /root/ExportTable2.sql &amp;
mysql -hHOSTIP3 -Pportnumber3 -u... -p... -A -Ddbname &lt; /root/ExportTable3.sql &amp;
wait
rm -f /root/ExportTable[123].sql &amp;


As show from these steps, these things should be shell scripted and perhaps crontab'd.



Here is another maneuver: If the tables are MyISAM, you could copy the MyISAM tables (.frm, .MYD, and .MYI files for each table) in other folders (databases in the eyes of mysqld) instead of doing mysqldumps, and perform similar operations as mentioned before. Make sure no writes to the tables take place during the copy.