Details
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Type:
Task
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Status: Open
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Priority:
Minor
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Resolution: Unresolved
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Fix Version/s: 10.2
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Component/s: None
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Labels:
Description
The mysqlbinlog client program needs to be updated to support GTID.
Here is a suggested list of things to be done:
- The --start-position and --stop-position options should be able to take
GTID positions; or maybe there should be new --start-gtid and --stop-gtid
options. Like "--start-gtid=0-1-100,1-2-200,2-1-1000".
- A GTID position means the point just after that GTID. So starting from
GTID 0-1-100 and stopping at GTID 0-1-200, the first GTID output will
probably be 0-1-101 and the last one 0-1-200. Note that if some domain is
not specified in the position, it means to start from the begining,
respectively stop immediately in that domain.
- Starting and stopping GTID should work both with local files, and with
--read-from-remote-server. For the latter, there are a couple of extra
things that need doing in the master-slave protocol, see
get_master_version_and_clock() in sql/slave.cc.
- At the end of the dump, put these statements, to reduce the risk of those session variables incorrectly spilling into subsequent statements run in the same session:
SET session.server_id = @@global.server_id,
session.gtid_domain_id=@@global.gtid_domain_id;
Probably some more things will come up during the work, but this looks like a
reasonable start.
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Some suggestions for getting started with this:
I would recommend to start by reading the GTID documentation, and
experimenting with all the relevant features described there, to familiarise
yourself with it. The main thing is to understand the concept of GTID position
and binlog order, and the relation to replication domains:
https://mariadb.com/kb/en/mariadb/global-transaction-id/
There are also some blog posts:
http://kristiannielsen.livejournal.com/16826.html
http://kristiannielsen.livejournal.com/17008.html
http://kristiannielsen.livejournal.com/17238.html
And similarly, familiarise yourself with mysqlbinlog and how it would make
sense for it to be extended to support GTID.
Then make a detailed proposal for how the user-visible interface of
mysqlbinlog should be extended, and send it to the list for comments.
The next step will be to understand the concept of binlog state
(@@gtid_binlog_state), and how it is used to deal correctly with out-of-order
GTID sequence numbers in binlogs. This is mostly an internal implementation
detail, but necessary to be able to correctly identify starting and stopping
GTID positions in all cases.
This is actually a really good starter project for someone to get into working with the GTID code.
The tasks requires getting some moderate understanding on how GTID works in general, but the actual code that needs to be worked on is fairly isolated and doesn't need to touch a majority of the GTID and replication stuff.