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Jay Janssen Lead Consultant
February 5th, 2014
What’s new in Percona Xtradb Cluster 5.6
www.percona.com
Overview
PXC 5.6 is the aggregation of Percona Server 5.6 Codership MySQL 5.6 patches Galera 3.x
Agenda Major new features Async replication and PXC 5.6 5.6 features that play nicely (or not) with Galera Future features Questions
www.percona.com
What is Percona XtraDB Cluster?
Read and Write anywhere Innodb cluster Highly available quorum-based failover Synchronous replication for data consistency Cluster responsible for node state PXC product 2 years in GA with 5.5, 13 releases
total, over 150k downloads Lots of development effort in the test suite Easy to migrate from and integrated with MySQL
async replication
Galera Replication Enhancements
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Replication overhead for Keys
Keys track all Schemas, Tables, and PK/UKs/FKs of rows being modified in the writeset
250k row inserts ala sysbench prepare
Rep
licat
ed M
Byte
s
0
12.5
25
37.5
50
Galera 2 Galera 3
1.915.2545.2545.25
RBRKeys
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Keys are now hashed
Hashed keys reduces writeset sizes Especially for large key columns !
Single INSERT writeset size
Byte
s
0
100
200
300
400
G2 INT G2 CHAR(128) G3 FLAT8 G3 FLAT16
7147
174
58223223223223 RBR
Keys
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Improved Memory usage (certification index)
mysqld RSS
Kill
obyt
es
0
175,000
350,000
525,000
700,000
wsrep_provider=none Galera 2 Galera 3
384,252
646,444
170,664 198,428197,460168,684
Startup ((innodb_buffer_pool_populate=ON) After Large Trx
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Overall improvements
Writesets have a new format faster certification less memory checksums Writeset keys stored as hashes FLAT8/FLAT16 Socket Checksums CRC32-C (hw accel where supported)
WAN Segments
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Multiple Datacenter Cluster
Datacenter 1
Datacenter 2
Datacenter 3
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Replication without Segments
Datacenter 1
Datacenter 2
Datacenter 3
Client commits here
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Cluster segments
Set gmcast.segment distinct per-location All nodes in colo1 have gmcast.segment=1 All nodes in colo2 have gmcast.segment=2 etc. Benefits Replication traffic is minimized between segments Donor selection prefers local segment
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Replication with Segments
Datacenter 1
Datacenter 2
Datacenter 3
Client commits here
gmcast.segment=2
gmcast.segment=1
gmcast.segment=3
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Donor Selection with Segments
Datacenter 1
Datacenter 2
Datacenter 3
gmcast.segment=2
gmcast.segment=1
gmcast.segment=3
Joiner
prefers local nodes
Asynchronous Replication into the cluster
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Any node can be a slave
node1
node3 node2
async master
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Galera 2 behavior
async
begin
apply
commit request
replicate
certify
commit finalized
slave node
begin
apply
certify
commit finalized
node2
begin
apply
certify
commit finalized
node3cy
cle
per r
eplic
ated
tran
sact
ion
Galera <= 2.x or wsrep_preordered=OFF
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Galera 3 with wsrep_preordered=ON
async
replicate
certify*
commit finalized
slave node
begin
apply
certify*
commit finalized
node2
begin
apply
certify*
commit finalized
node3
cycl
e pe
r rep
licat
ed tr
ansa
ctio
n
Galera 3+ and wsrep_preordered=ON
begin
apply
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When to use wsrep_preordered
wsrep_preordered=ON Better performance Does not allow for conflicts with any other writes No parallel apply for these transactions Good for Master / Slave to Cluster migration wsrep_preordered=OFF Detects conflicts with any other writes Allows parallel apply Good for permanent Cluster-is-a-slave
Asynchronous Replication out of the cluster
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5.6 async GTID integration
Every node with log-bin will have the same GTID for the same transaction
node1
node3 node2
async slave
node1
failed node2
async slave
CHANGE MASTER TO MASTER_HOST='node2',
MASTER_AUTO_POSITION=1
General 5.6 Improvements
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Can I use <5.6 feature> in PXC?
Every new feature works fine within a single node E.g., Innodb Full Text Indexes, Partitioning,
Optimizer enhancements, Performance Schema, etc.
Don’t expect automatic “cluster” support E.g., Online DDL improvements memcached server https://bugs.launchpad.net/percona-xtradb-
cluster/+bug/1254126
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Minimal RBR images
Pre-5.6 RBR is full row images for any row change 5.6 adds binlog_row_image=minimal (not default) Seems fine with PXC RBR image is black-box to Galera 1 Minute Sysbench Update Test (1 col out of 3 modified)
MB
Rep
licat
ed
0
17.5
35
52.5
70
full minimal
13.4
62.3
Upgrading a 5.5 cluster to 5.6
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The easy way
Take the downtime and upgrade it all at once Check for my.cnf settings that are not 5.6
compatible Start each node with “wsrep_provider=none” Run mysql_upgrade Shutdown again Bootstrap normally
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Rolling upgrade
RBR 5.6 -> 5.5 replication is broken For each 5.6 upgraded node Compatibility options with 5.5 must be set Galera socket.checksum=1 Don’t SST 5.5 to 5.6! Don’t write on these nodes! Before last node, flip application to 5.6 nodes Take down remaining 5.5 node(s) for upgrade Rolling restart to remove 5.5 compat options http://bit.ly/pxc56-rolling-upgrade
Odds and Ends
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My Favorite Bug Fixes
Adding auto_increment column to existing table doesn’t cause inconsistency with auto_increment_control
wsrep_local_bf_aborts catches all BF aborts now wsrep_flow_control_sent/received now global
counters wsrep_max_ws_size/ws_rows moving towards
being properly enforced now*
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Future Features
Automatic huge transaction fragmentation/streaming support
Non-blocking DDL support Cluster tolerance to inconsistencies Intelligent inconsistency handling (e.g., node voting) Intelligent donor selection (e.g., check gcache) Performance optimizations (i.e., multi-core) Multiple provider support
Questions?
Advanced Rates End March 2nd at 11:30pm PST, 2014 !
Special Discount for Webinar Attendees: Use Code WebinarSC to receive 10% off of standard
rates (new registrations only) !
http://www.percona.com/live/mysql-conference-2014/
!!!
