Dear MySQL Users,
MySQL Cluster is the distributed, shared-nothing variant of MySQL.
This storage engine provides:
- In-Memory storage - Real-time performance (with optional
checkpointing to disk)
- Transparent Auto-Sharding - Read & write scalability
- Active-Active/Multi-Master geographic replication
- 99.999% High Availability with no single point of failure
and on-line maintenance
- NoSQL and SQL APIs (including C++, Java, http and Memcached)
MySQL Cluster 7.2.20, has been released and can be downloaded from
http://www.mysql.com/downloads/cluster/
where you will also find Quick Start guides to help you get your
first MySQL Cluster database up and running.
The release notes are available from
http://dev.mysql.com/doc/relnotes/mysql-cluster/7.2/en/index.html
MySQL Cluster enables users to meet the database challenges of next
generation web, cloud, and communications services with uncompromising
scalability, uptime and agility.
More details can be found at
http://www.mysql.com/products/cluster/
Enjoy !
Changes in MySQL Cluster NDB 7.2.20 (5.5.43-ndb-7.2.20) (2015-04-13)
MySQL Cluster NDB 7.2.20 is a new release of MySQL Cluster,
incorporating new features in the NDB storage engine, and
fixing recently discovered bugs in previous MySQL Cluster NDB
7.2 development releases.
Obtaining MySQL Cluster NDB 7.2. MySQL Cluster NDB 7.2
source code and binaries can be obtained from
http://dev.mysql.com/downloads/cluster/.
This release also incorporates all bugfixes and changes made
in previous MySQL Cluster releases, as well as all bugfixes
and feature changes which were added in mainline MySQL 5.5
through MySQL 5.5.43 (see Changes in MySQL 5.5.43 (Not yet
released)
(http://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-43.h
tml)).
Bugs Fixed
* It was found during testing that problems could arise
when the node registered as the arbitrator disconnected
or failed during the arbitration process.
In this situation, the node requesting arbitration could
never receive a positive acknowledgement from the
registered arbitrator; this node also lacked a stable set
of members and could not initiate selection of a new
arbitrator.
Now in such cases, when the arbitrator fails or loses
contact during arbitration, the requesting node
immediately fails rather than waiting to time out. (Bug
#20538179)
* The maximum failure time calculation used to ensure that
normal node failure handling mechanisms are given time to
handle survivable cluster failures (before global
checkpoint watchdog mechanisms start to kill nodes due to
GCP delays) was excessively conservative, and neglected
to consider that there can be at most
number_of_data_nodes / NoOfReplicas node failures before
the cluster can no longer survive. Now the value of
NoOfReplicas is properly taken into account when
performing this calculation. (Bug #20069617, Bug
#20069624)
References: See also Bug #19858151, Bug #20128256, Bug
#20135976.
* When a data node fails or is being restarted, the
remaining nodes in the same nodegroup resend to
subscribers any data which they determine has not already
been sent by the failed node. Normally, when a data node
(actually, the SUMA kernel block) has sent all data
belonging to an epoch for which it is responsible, it
sends a SUB_GCP_COMPLETE_REP signal, together with a
count, to all subscribers, each of which responds with a
SUB_GCP_COMPLETE_ACK. When SUMA receives this
acknowledgment from all subscribers, it rports this to
the other nodes in the same nodegroup so that they know
that there is no need to resend this data in case of a
subsequent node failure. If a node failed before all
subscribers sent this acknowledgement but before all the
other nodes in the same nodegroup received it from the
failing node, data for some epochs could be sent (and
reported as complete) twice, which could lead to an
unplanned shutdown.
The fix for this issue adds to the count reported by
SUB_GCP_COMPLETE_ACK a list of identifiers which the
receiver can use to keep track of which buckets are
completed and to ignoreany duplicate reported for an
already completed bucket. (Bug #17579998)
* When performing a restart, it was sometimes possible to
find a log end marker which had been written by a
previous restart, and that should have been invalidated.
Now when when searching for the last page to invalidate,
the same search algorithm is used as when searching for
the last page of the log to read. (Bug #76207, Bug
#20665205)
* When reading and copying transporter short signal data,
it was possible for the data to be copied back to the
same signal with overlapping memory. (Bug #75930, Bug
#20553247)
* When a bulk delete operation was committed early to avoid
an additional round trip, while also returning the number
of affected rows, but failed with a timeout error, an SQL
node performed no verification that the transaction was
in the Committed state. (Bug #74494, Bug #20092754)
References: See also Bug #19873609.
* Cluster API: When a transaction is started from a cluster
connection, Table and Index schema objects may be passed
to this transaction for use. If these schema objects have
been acquired from a different connection
(Ndb_cluster_connection object), they can be deleted at
any point by the deletion or disconnection of the owning
connection. This can leave a connection with invalid
schema objects, which causes an NDB API application to
fail when these are dereferenced.
To avoid this problem, if your application uses multiple
connections, you can now set a check to detect sharing of
schema objects between connections when passing a schema
object to a transaction, using the
NdbTransaction::setSchemaObjectOwnerChecks() method added
in this release. When this check is enabled, the schema
objects having the same names are acquired from the
connection and compared to the schema objects passed to
the transaction. Failure to match causes the application
to fail with an error. (Bug #19785977)
* Cluster API: The increase in the default number of
hashmap buckets (DefaultHashMapSize API node
configuration parameter) from 240 to 3480 in MySQL
Cluster NDB 7.2.11 increased the size of the internal
DictHashMapInfo::HashMap type considerably. This type was
allocated on the stack in some getTable() calls which
could lead to stack overflow issues for NDB API users.
To avoid this problem, the hashmap is now dynamically
allocated from the heap. (Bug #19306793)
* Cluster API: A scan operation, whether it is a single
table scan or a query scan used by a pushed join, stores
the result set in a buffer. This maximum size of this
buffer is calculated and preallocated before the scan
operation is started. This buffer may consume a
considerable amount of memory; in some cases we observed
a 2 GB buffer footprint in tests that executed 100
parallel scans with 2 single-threaded (ndbd) data nodes.
This memory consumption was found to scale linearly with
additional fragments.
A number of root causes, listed here, were discovered
that led to this problem:
+ Result rows were unpacked to full NdbRecord format
before they were stored in the buffer. If only some
but not all columns of a table were selected, the
buffer contained empty space (essentially wasted).
+ Due to the buffer format being unpacked, VARCHAR and
VARBINARY columns always had to be allocated for the
maximum size defined for such columns.
+ BatchByteSize and MaxScanBatchSize values were not
taken into consideration as a limiting factor when
calculating the maximum buffer size.
These issues became more evident in NDB 7.2 and later
MySQL Cluster release series. This was due to the fact
buffer size is scaled by BatchSize, and that the default
value for this parameter was increased fourfold (from 64
to 256) beginning with MySQL Cluster NDB 7.2.1.
This fix causes result rows to be buffered using the
packed format instead of the unpacked format; a buffered
scan result row is now not unpacked until it becomes the
current row. In addition, BatchByteSize and
MaxScanBatchSize are now used as limiting factors when
calculating the required buffer size.
Also as part of this fix, refactoring has been done to
separate handling of buffered (packed) from handling of
unbuffered result sets, and to remove code that had been
unused since NDB 7.0 or earlier. The NdbRecord class
declaration has also been cleaned up by removing a number
of unused or redundant member variables. (Bug #73781, Bug
#75599, Bug #19631350, Bug #20408733)
On behalf of the Oracle/MySQL Build and Release Team,
Murthy Narkedimilli
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MySQL Cluster 7.2.20 has been released (no replies)
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