The slides are written, uploaded and the code snippets work. I’m ready to present.
One of the topics will be merging binlogs which is what multi-master replication is all about on the low level. A common example is sharding where you have several masters which share the same table-structures, but store the data independently. This is great for scaling out, but tricky if you have to run a query over the full dataset.
The logfiles look like:
$ mysqlbinlog binlog-merge-1.log -s
SET TIMESTAMP=1240066015/*!*/;
INSERT INTO tbl VALUES ( 1 )
/*!*/;
SET TIMESTAMP=1240066017/*!*/;
INSERT INTO tbl VALUES ( 3 )
/*!*/;
# End of log file
ROLLBACK /* added by mysqlbinlog */;and
$ mysqlbinlog binlog-merge-2.log -s
SET TIMESTAMP=1240066016/*!*/;
INSERT INTO tbl VALUES ( 2 )
/*!*/;
SET TIMESTAMP=1240066018/*!*/;
INSERT INTO tbl VALUES ( 4 )
/*!*/;
# End of log file
ROLLBACK /* added by mysqlbinlog */;As the two binlogs are independent and can’t contain collisions we can just merge the two binlogs based on the timestamp:
$ mysqlbinlog binlog-merged.log -s
SET TIMESTAMP=1240066015/*!*/;
INSERT INTO tbl VALUES ( 1 )
/*!*/;
SET TIMESTAMP=1240066016/*!*/;
INSERT INTO tbl VALUES ( 2 )
/*!*/;
SET TIMESTAMP=1240066017/*!*/;
INSERT INTO tbl VALUES ( 3 )
/*!*/;
SET TIMESTAMP=1240066018/*!*/;
INSERT INTO tbl VALUES ( 4 )
/*!*/;
# End of log file
ROLLBACK /* added by mysqlbinlog */;In my session I’ll show you what is going in the background to merge any number of binlogs into one binlog. It is less than 50 lines of lua-code.
Just add a network-interface to it and another problem to make MySQL “sharding-complete” is solved.