MySQL Cluster 7.4.5

A real-time open source transactional memory database designed for fast, always-on access to data under high throughput conditions

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What's new in MySQL Cluster 7.4.5:

  • 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)
DROP DATABASE failed to remove the database when the database directory contained a .ndb file which had no corresponding table in NDB. Now, when executing DROP DATABASE, NDB performs an check specifically for leftover .ndb files, and deletes any that it finds. (Bug #20480035)
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 #20062754)
During a node restart, if there was no global checkpoint completed between the START_LCP_REQ for a local checkpoint and its LCP_COMPLETE_REP it was possible for a comparison of the LCP ID sent in the LCP_COMPLETE_REP signal with the internal value SYSFILE->latestLCP_ID to fail. (Bug #76113, Bug #20631645)
When sending LCP_FRAG_ORD signals as part of master takeover, it is possible that the master not is not synchronized with complete accuracy in real time, so that some signals must be dropped. During this time, the master can send a LCP_FRAG_ORD signal with its lastFragmentFlag set even after the local checkpoint has been completed. This enhancement causes this flag to persist until the statrt of the next local checkpoint, which causes these signals to be dropped as well. This change affects ndbd only; the issue described did not occur with ndbmtd. (Bug #75964, Bug #20567730)
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)
NDB node takeover code made the assumption that there would be only one takeover record when starting a takeover, based on the further assumption that the master node could never perform copying of fragments. However, this is not the case in a system restart, where a master node can have stale data and so need to perform such copying to bring itself up to date. (Bug #75919, Bug #20546899)
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. 

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MySQL Cluster
MySQL Cluster utilizes a “shared nothing” architecture which does not require any additional infrastructure investment to provide 99.999% data availability with no single point of failure.

MySQL Cluster is primarily an in-memory database, but one that also provides optional disk-based data all available via a SQL interface or optionally via a high-performance native C++ or Java interface using the Carrier Grade Edition.

Last updated on March 21st, 2015

Runs on: Mac OS X 10.8 or later (Intel only)


#database engine #database interface #mysql database #database #transaction #engine #sql

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