I presented these slides at the London MySQL Meetup on Thursday 6 March 2014

1. Ivan
Zoratti
GTIDs
Explained
MySQL 5.6, MariaDB 10, Galera 3
V1403.01

2. MySQL
5.6
Replication
2
M1
S1 S2 S3

3. GTID
in
MySQL
5.6
3
3E11FA47-71CA-11E1-9E33-C80AA9429562:23
Transaction
ID
Sequence
number
determined
by
the
order
in
which
the
transaction
was
committed
on
this
server
!
Transaction
ID
=
=
Sequence
Source
ID
Identifies
the
originating
server
!
Source
ID
=
=
Server
UUID

4. GTID
in
MySQL
5.6
•Used
to
identify
a
transaction
in
a
MySQL
5.6
Cluster
•Sets
are
also
allowed
to
identify
an
interval
of
transactions
•Preserved
between
masters
and
slaves,
i.e.
they
identify
the
source
(origin)
of
a
transaction
•Transactions
with
the
same
GTID
cannot
be
applied
more
than
once
•Benefits
•Simplified
failover
(with
CHANGE
MASTER
TO
and
MASTER_AUTO_POSITION=1)
•Guarantees
slave
consistency
by
checking
Executed_Gtid_Set
4

5. Galera
Cluster
• Read
&
Write
access
to
any
node
• Client
can
connect
to
any
node
• There
can
be
several
nodes
• Automatic
node
provisioning
• Replication
is
synchronous
5

6. GTID
in
Galera
3
•Used
to
identify
a
state
change
•i.e.
to
identify
write
operations
to
the
database
•Used
to
identify
the
state
itself
•i.e.
the
last
state
change
6

7. GTID
in
Galera
3
7
!
45eec521-2f34-11e0-0800-2a36050b826b:94530586304
An
ordinal
sequence
number
(seqno,
64-­‐bit
signed
integer)
to
denote
the
position
of
the
change
in
the
sequence
!
Sequence
=
=
Change
in
the
Cluster
State
UUID
I
uniquely
identifies
the
state
and
the
sequence
of
changes
it
undergoes
!
UUID
=
=
Cluster
ID

8. GTID
in
Galera
3
•A
Galera
Cluster
acts
as
a
single
node
•No
holes
in
the
sequence
•Stored
in
grastate.dat
•5ee99582-­‐bb8d-­‐11e2-­‐b8e3-­‐23de375c1d30:8204503945773
<<<
Typical
sequence
•5ee99582-­‐bb8d-­‐11e2-­‐b8e3-­‐23de375c1d30:-­‐1
<<<
The
node
has
crashed
•00000000-­‐0000-­‐0000-­‐0000-­‐000000000000:-­‐1
<<<
The
node
has
crashed
during
the
execution
of
a
non
transactional
operations
(e.g.
a
DDL
op)
or
the
op
has
been
aborted
8

9. MariaDB
10
Replication
9

10. GTID
in
MariaDB
10
10
!
#131109 14:59:59 server id 1 end_log_pos 4151 GTID XXX-YYY-ZZZ
/*!100001 SET @@session.gtid_seq_no=ZZZ*//*!*/;
Sequence
Number
64bit
unsigned
It
increases
monotonically
at
each
commit
It
is
applied
for
each
Event
Group,
i.e.,
for
each
BEGIN/COMMIT
or
for
groups
that
have
no
BEGIN/COMMIT
(for
example
DDL
commands,
TRUNCATE
and
others)
Server
ID
32bit
unsigned
The
server_id
value
for
the
MariaDB
instance
Domain
ID
32bit
unsigned
The
domain_id
value
for
the
Replication
stream

11. GTID
in
MariaDB
10
•1
GTID
for
each
event
group
•Groups
can
be
executed
in
parallel
•Transaction
safe
(stored
in
an
InnoDB
table,
not
in
a
file)
•MASTER_USE_GTID=gtid_slave_pos
-­‐
great
to
position/reposition
slave
nodes
•Domain
ID
is
used
to
guarantee
that
this
works
with
multi-­‐source
replication
11