GraphDB-Enterprise Release Notes

Starting from version 6, GraphDB now includes three separate products with their own version numbers: GraphDB Engine, GraphDB Workbench and GraphDB Connectors (this was an experimental feature in 6.0 and 6.1). New features and significant bug-fixes/updates for the last few releases are recorded here. Each component's full version numbers is given as:

{panel}major.minor.build_number{panel}

e.g. 5.3.5928 where the major number is 5, the minor number is 3 and the build number is 5928.
The integrated releases have their own version, e.g. 6.2.0, 6.2.1 and so on.

Releases with the same major and minor version numbers do not contain any new features. The only difference is that releases with later build numbers contain fixes for bugs discovered since the previous release. New or significantly changed features are released with a higher major or minor version number.

Highlights:

* bug fixes in the Connectors and the Workbench
* new features in the Connectors
* no changes in the engine

Component versions:
||Sesame||Engine||Workbench||Connectors||
| 2.7.8 | 6.2.2 | 6.5.2 | 4.1.0 |

h5. GraphDB Engine 6.2.2

No changes. This is a release of GraphDB that includes changes only in the Workbench and the Connectors. If you use the Connectors or the Workbench we strongly recommend you to upgrade.

h5. GraphDB Workbench 6.5.2

* WB-198 Fix: Changing the password of the default admin user works only until tomcat is restarted
* WB-490 Fix: Adding a location that was autocompleted in the browser results in an error

h5. GraphDB Connectors 4.1.0

* STORE-165 New: Improved splitting for facet field values
* STORE-170 Fix: Solr connector overrides "rows" and "start" for raw queries
* STORE-191 Fix: Lucene connector does not index xsd:dateTime properly
* STORE-192 Fix: Invalid values in typed literals are fatal but should rather be ignored (Lucene)
* STORE-193 Fix: Field sync option "facet" not interpreted correctly (Lucene)
* STORE-194 Fix: The field option "indexed" is not interpreted correctly
* STORE-195 New: Unable to specify cluster name for Elasticsearch
* STORE-196 New: Upgrade Elasticsearch to 1.6.0
* STORE-197 Fix: Entity filter graph() not working correctly for statements in named graphs
* STORE-200 New: Upgrade Lucene and Solr to 4.10.4
* STORE-201 New: Custom analyzers in Elasticsearch are unusable without a way to specify analyzer per field


h1. GraphDB 6.2.2

*Highlights:*
* bugfixes
* Storage tool enhancements

h5. GraphDB Engine 6.2.2

*Features:*

* OWLIM-2151 Storage tool discovers wrong page size in the page index and storage files
* OWLIM-2199 Storage tool index consistency check - groups statements by flags and compares counts for each index

*Bugfixes:*
* OWLIM-2082 Fix: Inconsistencies in GraphDB collection identified by the StorageTool

h5. GraphDB Workbench 6.5.1

* no changes

h5. GraphDB Connectors 4.0.1

* no changes

h1. GraphDB 6.2.1

*Highlights:*

* New Transactional Entity Pool
* Connectors - major imrovements and new features
* Parallel Reasoning in LoadRDF
* Workbench - new Import, Export and Repository views
* The Lucene connector is now included in GraphDB SE

h5. GraphDB Engine 6.2.1

*Features:*
* OWLIM-1682 Redesign the Entity pool so that it becomes transactional.
A new [transactional entity pool|GraphDB-SE Entity Pool] has been created. This allows the Connectors to be run in cluster mode.

* OWLIM-1810 Parallel inference
The [LoadRDF tool|GraphDB62:GraphDB-SE LoadRDF tool] now supports parallel (multithreaded) reasoning mode. The improvement of the loading speed is between 25% and 100%, measured on SPB-64m and Wordnet datasets, respectively.

*Miscellaneous & bug fixes:*
* \[Enterprise\] improved reporting for causes of replication failure
* \[Enterprise\] Detect and report missing master URL
* Made plugins aware of whether the entity pool is transactional (the plugins can call EntityPool.isTransactional())
* Added fingerprint tracking for the entity pool
* StorageTool - the tool is now part of the official documentation. The scan report now says whether the repository image is OK or not, in addition to the number of statements reported for each index
* LoadRDF uses lock-free data structure for faster multithreaded inference
* LoadRDF - the reverse cache option was removed
* GRAP-4 A fix for anomalous query behaviour
* OWLIM-2069 Fixed minor memory leak (which was present in OWLIM 5.4 as well)
* OWLIM-2086 Fix: The vars of the PluginPattern were not cloned (this potentially leads to a wrong result)
* OWLIM-2177 Fix: Inconsistency checks abort the transaction but the statements are still there on further transactions

h5. GraphDB Workbench 6.5.1

*Features:*
* OWLIM-2021 New Import View
-- the import is now asynchronous and keeps the state between restarts
-- there are two new ways to import a file - from a text area and from a data URL
-- native support for chunking + retry for each import
-- REST endpoints for everything which can be reused by clients
-- much better UI

* OWLIM-2009 Create a new overhauled repository view based on Angular JS with better user experience
-- rethink the structure of the page so the active location is moved at the top along with the repositories
-- create a RESTful API that will allow client to do locations management through RESTful endpoints
-- lazy initialization for repositories

* OWLIM-2022 Create a new export view based on Angular JS
-- Exporting the whole repository should be much more explicit now
-- The export view now only uses the Sesame endpoints

* OWLIM-2087 The import operation now sends the input stream directly to Sesame (instead of uploading a temp file first)
* OWLIM-2089 Initialize the repositories as lazily as possible
* OWLIM-1643 Fixed: First load of workbench interface is too slow in tomcat

*Overall changes:*

* Removed the same as from the SPARQL view because it was leading to major bugs
* ~/.owlim-workbench is changed to ~/.graphdb-workbench so previous state in the workbench will be lost. There are changes to the contents of this folder, so a simple copy/rename of the old folder won't work.


*Bugfixes:*
* OWLIM-2146 Fix the label in add repository view to represent the parameters that were mentioned in the documentation
* OWLIM-2139 Workbench locks when trying to connect to location which is not currently available
* OWLIM-2137 The JMX connection and Sesame discovery don't work on AWS
* OWLIM-2120 JMX is not auto-configured properly when we do same container Sesame auto-discovery
* OWLIM-2119 Copying/sharing the current query doesn't work properly
* OWLIM-2016 Unable to remove/edit query samples from FireFox
* OWLIM-2005 Unicode text gets scrambled in SPARQL query window of GraphDB Workbench
* OWLIM-1999 Selecting a local location with repositories for another edition makes the UI unusable
* OWLIM-1997 The user should be able to change the password if there is no repository selected
* OWLIM-1975 Cluster view is not available in the menus
* OWLIM-1973 Unable to setup cluster with file location
* OWLIM-1964 SPQRQL view should allow users with read only access to make selects to a repository
* OWLIM-1963 Unable to SignOut from SPARQL View
* OWLIM-1961 Unable to save a long sample query
* OWLIM-1959 We shouldn't allow repository locations that are relative directories
* OWLIM-1958 Vertical scroll bar is over Save and Copy in the sparql view
* OWLIM-1930 Creating a master repository shouldn't result in an exception view but we should just show the repository as a non write repo
* OWLIM-1913 Workbench doesn't shutdown the repository manager on Tomcat shutdown
* OWLIM-1909 Workbench does not report error properly when it cannot load repository from a remote endpoint
* OWLIM-1877 Deleting a repository that is in the currently selected remote location through another place results in inconsistent state
* OWLIM-1874 Inferred and explicit statement count are inverted in the popover
* OWLIM-1864 There is no proper error message when you connect to a non existing remote location
* OWLIM-1826 Restarting the workbench doesn't activate the repository from last time because of NPE
* OWLIM-1824 Exception when paging through repository graphs
* OWLIM-1823 Workbench does not show additional column in results
* OWLIM-1819 Import doesn't support BinaryRDF (.brf)
* OWLIM-1785 Unable to get system info if there isn't location selected
* OWLIM-1764 Repository size is -1 and the reason is not available
* OWLIM-1782 Properly start the workbench if the directory for the location from the last time is missing and cannot be created
* OWLIM-1759 Error message appears when deleting a master repository
* OWLIM-1647 When the name of the repository is big enough the icons go on the next line and cannot be clicked

h5. GraphDB Connectors 4.0.1

* Solr and Elasticsearch now work in a cluster (EE edition only)
* Full support for default values: plain literals, literals with a datatype, literals with languages, URIs
* Full support for matching literal languages
* More control over how data is mapped:
-- field options more closely reflect the options in Lucene/Solr/Elasticsearch
-- control over how RDF literals are mapped to Lucene/Solr/Elasticsearch types
* Support for many more types of faceting and aggregations in Solr and Elasticsearch, e.g. ranges and histograms
* Improvements and extensions to the entity filter
* Bug fixes and optimizations

h1. GraphDB 6.1-SP3
This Service Pack 3 build addresses some reported problems with 6.1

h2. GraphDB Engine 6.1-b4371143

* OWLIM-1888 Better inference performance for datasets with big number of classes and onProperty restrictions
* Fixed a problem where queries containing UNION and BIND were under certain circumstances returning incorrect results
* New merge command for the storage tool
* OWLIM-1932 Count from graph http://www.ontotext.com/count does not work for describe queries
* OWLIM-1934 Removed some old and unwanted namespaces that were included by default
* OWLIM-1928 Added reversed numeric and date literal indices for better performance
* OWLIM-1990 Worker data is deleted when a plugin fails to initialize
* Using store-backed queue to keep transaction operations on the master - this should prevent out of memory errors when importing huge files


h2. GraphDB Workbench 6.4.1
- See all the release notes here: [https://confluence.ontotext.com/display/GraphDB6/GraphDB-Workbench+Release+Notes]


h2. GraphDB Connectors 3.1.4
- See all the release notes here: [https://confluence.ontotext.com/display/GraphDB6/GraphDB+Connectors+Release+notes]


h1. GraphDB 6.1-SP1
This Service Pack 1 build addresses consistency issue with the GraphDB Storage. The cluster's backup/restore functionality is also fixed.

h2. GraphDB 6.1.8410
- extended new cluster backup/restore to support multiple named backups. Important note: the backup now uses a name instead of an absolute folder
- fixes for the master URL parameter (autodetected in most cases, thus no need to specify manually)
- minor cluster improvements (shutdown on OOM during sync; worker: handling multiple initializations and no reporting of missing fingerprints on init; fixed race condition in replication; new internal URIs (not URLs) for replication)
- fixed: [owlim-1853] LoadRDF under Windows sometimes does not include statements in the PSO index and the indexes are incosistent;
- Added a check/warning to see if there is enough memory for the entity pool when it gets restored from persistence (-Xmx - cache-memory should be >= entity pool size * 1.25, i.e. 25% overhead is left for the datatype index and other in-memory structures included in the entity pool and for other purposes, e.g. for running queries)
- Constraint validation and support for multiple rulesets is out of its experimental stage and now in production. See the docs here: [https://confluence.ontotext.com/display/GraphDB6/GraphDB+Constraint+Validation]

h2. GraphDB Workbench 6.3.2
- See all the release notes here: [https://confluence.ontotext.com/display/GraphDB6/GraphDB-Workbench+Release+Notes]


h1. GraphDB - 6.1.8316
This is an Enterprise release only.

h2. Improvements (replication cluster):
- Tx Log stability improvements & fixes - scrapped optimistic join procedure; scrapped shared horizon & completed queue; fixed status patching base
- Improved logging detail
- Updates are dispatched to the other peers immediately once accepted and enqueued
- dedicated peer dispatch threads
- fixed split-brain recovery
- Client API: Changed the master retry policy (do not check every master too often; but still make sure that when previously unavailable master becomes available we detect that)

h2. Replication improvements:
- cleanup target directory on accepting replication data
- 60s timeout in replication client
- limited retries in the replication server
- replication client startup delay patch
- retry serving replication data on failure
- exposed exceptions thrown from the replication server

h2. Other improvements:
- The inferencer debug statistics were not displayed at shutdown because we used the SwitchableInferencer's ones instead of those in currentInferencer that did the job
- Created StorageTool app, used to Scan/Rebuild indexes in case of missing statements

h3. Fixes:
- [OWLIM-1838] Custom NTriples/NQuads parser: ArrayOutOfBoundsException can be thrown on empty lines while parsing and then NPE while trying to process t.getMessage() which may be null
- [OWLIM-1834] Fixed: LoadRDF Tool doesn't work with GraphDB Enterprise
- [W-44] Introduced a parameter 'in-clause-max-members' (defaults to 16) which limits the number of entities specified in the IN clause. If the IN clause contains more elements then it won't be optimized to a UNION query
- [W-55] Fixed the ASC/DESC issue in ORDER BY clause when the variable in the ORDER BY is in an OPTIONAL clause (the issue was different number of results returned in ASC/DESC cases).


h1. GraphDB version 6.1-RC1

Highlights:

- *Various stability fixes to the cluster*, including proper master shutdown sequence error handling, error-resilient synchronization threads, safe saving of configuration properties of the cluster config. The repository fingerprint now also reflects the number of statements and there is better handling of stress events which happen during transactions & dirty shutdowns (e.g. out of disk space)

- *Much faster write transactions* for small insert/update/delete operations on large repositories. Results on LDBC [Semantic Publishing Benchmark|http://ldbcouncil.org/developer/spb] (SPB) at 50M went up from 32 read and 12 write queries per second in ver. 6.0 to 40 reads/s and 31 writes/s in ver. 6.1. The improvement gets even more visible and SPB at 1B scale: from 10 reads/s and 2 writes/s in ver. 6.0 to 11 reads/s and 10 writes/s in ver. 6.1. In summary, GraphDB 6.1 is able to handle twice more updates at 50M scale and 5 times more updates at scale of 1 billion statements. This way GraphDB 6.1 is already capable to deal with true Dynamic Semantic Publishing scenario, like the one of [BBC|http://www.bbc.co.uk/blogs/legacy/bbcinternet/2012/04/sports_dynamic_semantic.html], at a scale of 1 billion statements and higher.
See more: http://www.ontotext.com/graphdb-benchmark-results/

- *Improved load capabilities for large new datasets in live databases* instances. Scenario description: there is a production cluster with average load - running LDBC-50m (SPB) with 4 reading threads (doing select queries) and 1 writing thread (doing update queries). We need to add a large dataset (e.g. DBPedia) with hundreds of millions statements -- as fast as possible, but without disrupting the overall cluster speed too much (not introducing write latency of more than 1-2s). The data set doesn't need inference, so it is loaded with the empty rule set.
Our implementation introduces a new "magic" statement (u, u, u), where u=<[http://www.ontotext.com/useParallelInsertion]>. If this statement is inserted in the beggining of the transaction, then the data will be loaded almost twice faster (it reuses parts of the load-chain from LoadRDF tool) and also the engine will temporarily switch the ruleset to 'emtpy'. We found that splitting the data set into 50k chunks is a good compromise between high loading speed and lower latency increase of parallel updates.

- Small *improvements in the bulk loading tools (LoadRDF)*. It is possible to load different files into different contexts now, as well as provide Statements programmatically to it. See the page for the LoadRDF for the details. [GraphDB-SE LoadRDF tool|GraphDB6:GraphDB-SE LoadRDF tool].&nbsp;These improvements, combined with the increased update speed, allow us to load the English part of DBPedia 2014 (566M statements), in less than an hour at speed of 179 905 statements/sec.

- Improvements in *GraphDB Workbench*: The focus with this release was on *security* (users, roles) as well as small stability and usability improvements.

This is an integrated release that includes:
- GraphDB Engine 6.0.8274
- GraphDB Workbench 6.2.3
- GraphDB Connectors 3.1.0

h1. GraphDB version 6.0-RC6

This is an integrated release that includes:
- GraphDB Engine 6.0.8120
- GraphDB Workbench 6.2.2
- GraphDB Connectors 3.1.0

h2. GraphDB Engine 6.0.8120

The focus on this release was further improvement of the updates speed on larger transactions (10K\+ statements) as well as overall stability.

Improvements:
- The transactions are serialized to JSON instead of XML. JSON Streaming parser is used - this minimizes the memory footprint of the master nodes
- improved handling of long transactions
- bigger transactions are compressed via GZip in the transaction log and when communicated between masters and workers
- GZipped updates can be sent via curl; add "Content-Encoding: gzip" header to use them
- Rule files can now be specified via HTTP and other protocols instead of local files

Fixes:
- Fixed: OWLIM-1610 OOM on the Master with large update (600k statements)
- Fixed JMX update statistics
- Removed the obsolete Remote Master flag in the replication cluster
- Master backup folder moved over under sesame data folder
- Fixed Lucene plugin to support Custom Analyzers/Scorers (this was broken on 6.0 releases due to plugin classloader not loading jars from the plugin directory)
- [OWLIM-1730|OWLIM-1730] Fixed handling of a failed initialisation within LiteralsPlugin
- [OWLIM-1712|OWLIM-1712] Query Optimizer does not apply 'strong' equality within FILTER when bot variables are used as subject of some statement patterns
- [OWLIM-1615|OWLIM-1615] Fixed how running queries are handled on shutdown

h2. GraphDB Workbench

- the full list of changes in the latest version is available in this page: [GraphDB-Workbench Release Notes|GraphDB6:GraphDB-Workbench Release Notes]

h2. GraphDB Connectors (experimental)

- the full list of changes in the latest version is available in this page: [GraphDB6:GraphDB Connectors Release notes]


h1. GraphDB version 6.0-RC5

This is an integrated release that includes:
- GraphDB Engine 6.0.8070
- GraphDB Workbench 6.0.2
- GraphDB Connectors 3.0.0.RC2

h2. GraphDB Engine 6.0.8070


h3. Major changes:

- Improvements to the HA Cluster wrt New Cluster Tests: improved intra-cluster communications, worker initialization, status reporting, improved diagnostics and logging;
- Query monitoring via JMX - the full text of the query is now visible
- Fixes for the Constraint Violation support & multiple rulesets
- Faster update speeds
-- Now using GraphDB Custom NTriples/NQuads parser by default (so NTriples, NQuad formats are parsed faster than other formats)
-- when a transaction is using the *empty* ruleset, the commit can added to all indexes in parallel. In order to use this experiment feature, add the special system statement: \_:b <[http://owlim.ontotext.com/owlim/useParallel]> \_:b in the beginning of the transacton. This makes sense for larger transactions (10K statements and above).

h3. Full list of changes:

- OWLIM-1628 Added a fix of the issue of not being able to explore a ruleset when the empty ruleset was set initially.
- OWLIM-1626 RepositoryException in Worker is not thrown by the Master
- OWLIM-1600 Query returns no results when using FILTER and BIND(if(...)) in it.
- T-10 Implemented automatic entity pool restore procedure which can recover a truncated entity pool and removes the statements from the repo using the IDs beyond the new entity pool size
- OWLIM-1603 Owlim crashes with lock error without obvious reasons (there is no other process that might have locked the repo).
- OWLIM-1592 Queries with at least one sub-select which intersect with an ordinary block of statement patterns perform poorly because of multiple clones and transforms of the Sesame's query model to Owlim's one.
- OWLIM-1593 Fixed bug in MainQuery.clone() (when using Subselect and there are OPTIONALs)
- OWLIM-1572 Query Monitoring - show query text instead of query id
- OWLIM-1559 Fixed property path bug when same property paths are repeated in the query
- F-320 JMX: NumberOfExplicitTriples and NumberOfTriples shows \-1 even though data has been written to the triple store
- OWLIM-1563 Fixed the issue with custom ruleset + disable-sameAs=true.
- OWLIM-1559 Implemented a shortcut in the MINUS operator which allows for faster calculation when the MINUS is over two subqueries with one triple pattern (which may have filters).

h2. GraphDB Workbench

- the full list of changes in the latest version is available in this page: [GraphDB-Workbench Release Notes|GraphDB6:GraphDB-Workbench Release Notes]

h2. GraphDB Connectors (experimental)

- the full list of changes in the latest version is available in this page: [GraphDB6:GraphDB Connectors Release notes]

h1. GraphDB version 6.0-RC4

This is an integrated release that includes:
- GraphDB Engine 6.0.7914
- GraphDB Workbench 6.0.1
- GraphDB Connectors 3.0.0.RC2


h1. GraphDB version 6.0-RC3 (build 7914)

h2. Fixes:

* The plugins were moved to <webapps>/openrdf-sesame/WEB-INF/classes/plugins;
* Running GraphDB under embedded Tomcat failed with NPE (because of non existing webapps/ folder).

h1. GraphDB version 6.0-RC2 (build 7892)

h2. Improvements:

* Added mini LDBC Semantic Publishing Benchmark ([http://ldbc.eu]) into benchmark/ldbc-spb folder in the distribution;
* The plugins are now in <webapps>/openrdf-sesame/plugins folder. Lucene plugin is enabled by default. This could be overwritten by the \-Dregister-external-plugins option;
* Minor rearrangement of the files in the main distribution folder (all .pie files are put into rules/ subfolder, the scripts into scripts/ subfolder).

h2. Fixes:

* Fixed issue with the default/evaluation license;
* Fixed issue with the LoadRDF tool.


h1. GraphDB version 6.0 (build 7784)

GraphDB 6.0 is a re-branded Owlim 5.6 version. The differences are given in the last stable Owlim 5.4 release.

h2. Improvements:

* High Availability Cluster;
* Fast writes in SAFE Mode (OWLIM 5.5 improvement, which lead to incompatible binary formats between 5.4 and 5.5+);
* LoadRDF tool for faster bulk loading of data; speeds \~100KSt/s and above, without inference;
* Explain Plan like functionality;
* LVM-based Backup and Replication.

h2. Fixes:

* Databases created with one setting of the "entity-id-size" parameter (32 vs 40-bit) and opened with another setting, would crash in versions prior to 6.0. Now an exception is thrown and the repository is not initialized.



h1. Version 5.6 (build 7713)

h2. Improvements:

* [LVM-based Backup and Replication|OWLIM56:LVM-based Backup and Replication] \- Backup can optionally be based on the LVM Shadow Volume Copy - which makes it faster and the worker is released a few seconds after the backup is started (ported from 5.4).
* [New Cluster Test (cluster deployment and test tool)|OWLIM56:New Cluster Test (cluster deployment and test tool)] \- a tool for automated deployment and testing of clusters of various sizes. Can deploy on AWS and local instances. Supports docker format. Allows for acceptance, stress and load tests to be run on the deployed clusters. Optionally, creates Nagios configuration for the deployed cluster.
* LoadRDF tool - a tool for a faster bulk loading of data, which has been merged from 5.5 branch.
* Merged EntityPool Reverse Cache from 5.5 - speeds up large updates (100\+ statements).

h2. Fixes:

* All AcceptanceTests that were previously failing are now fixed:
** Improved communication between master and worker nodes with respect to the acceptance tests;
** Worker thread: fixed out-of-sync handling upon initialisation;
* Improved logging, fixed the skip of some stacktraces by the JVM in particular;
* Initialisation of 5.6 worker from 5.4 image now skip "entityIdSize" and InferencerCRC from owlim.properties.

h1. Version 5.6 beta 3 (build 7659)

Fixes:
* cluster - empty worker initialisation;
* worker - initial update handling;
* log sync: 10s wait between idle rounds (network bandwidth optimisation);
* Tx log: initialisation bug fixed;
* update might fail when replication is in progress;
* miscellaneous bug fixes in the cluster utils (deployment/status) and proxies restart;
* detailed logging:
** replication cluster worker events;
** HTTP client stats;
** Tx log initialisation.

Known issues:
* AcceptanceTests failing: W4, M4, MW3, MW7, MW8;
* the new/experimental LVM backup/restore feature is not yet ported from 5.4 (and thus MW10 and MW11 Acceptance Tests are not implemented, because they are based on it).

h1. Version 5.6 beta 2 (build 7523)

Fixes:
- updated AcceptanceTests in the MastersAndWorkers section;
- replication start/wait methods improved;
- several fixes to the TxLog protocol;
- fixed replication logic to delete the Worker repo, only when the remote worker confirms the replication;
- additional sanity checks added to the Master-to-Master and Master-to-Worker synchronisation;
- improved logging, incl. "SPLITBRAIN" events logged both to logs and to JMX.

Known issues:
- some MW\* tests with the forced replication fail randomly, but rarely - related to the Proxy tool.

h1. Version 5.6 beta 1 (build 7368)

Ontotext redesigned its cluster architecture to support the case of two or more separate data centres (each with its own Master and Worker nodes), and to provide asynchronous transactions and Master fail-over. OWLIM Enterprise already supported Master-Worker clusters with Automatic Replication, Load-balancing and Transaction Logs, but in this release these components are improved. OWLIM 5.6 is based on 5.5 and inherits its write performance improvements.
* [OWLIM56:Client Fail-over Utility|OWLIM56:Client Fail-over Utility], which can be configured to fallback to the next master, if the first master becomes unavailable;
* Better TransactionLog support (see: [OWLIM56:Transaction Log Improvements]) - the updates are synchronised between all masters in all data centers;
* All Masters are now Read/Write;
* [OWLIM56:Smart Replication];
* Protocol backwards compatibility - the ability to upgrade the OWLIM cluster without downtime, following the OWLIM Upgrade Procedure;
* [External Plug-ins|OWLIM56:External Plug-ins] \- the plugins in OWLIM are moved into a separate plugin directory, and now can be upgraded/maintained separately.

h2. Known issues:

* Transaction consistency concern. In the new cluster, the Master responds to an update from a client as soon as the test node completes it.

In a single threaded scenario the next query can be evaluated on a node that still has either not received it or not completed it which could lead to inconsistency from the client application point of view. This deviates from the update processing in 5.4, where the response is created after the last of available nodes completes it\[OWLIM-1483\].