v5.0.1

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast Platform 5.0.1 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Hazelcast Platform is a major release which unifies
the former Hazelcast IMDG and Jet products in a
single solution. The changes are summarized below.

For information about upgrading from previous IMDG and Jet
releases, see the Upgrade chapter at https://docs.hazelcast.com/hazelcast/latest.

To learn about the changes in previous IMDG and Jet releases, see https://docs.hazelcast.org/docs/rn/ and
https://jet-start.sh/blog/.

Enhancements

• Updated log4j2 dependency version to 2.15.0 in Hazelcast's root pom.xml. [#20153]
• Updated Avro dependency version to 1.11.0 and AWS SDK to 1.12.120 in Hazelcast's root pom.xml. [#20008], [#20007]
• Introduced a system property for allowing you to audit that all the Hazelcast instances
  running in your environment have the instance tracking file name set correctly in the configuration.
  See the note in https://docs.hazelcast.com/hazelcast/latest/maintain-cluster/monitoring#instance-tracking. [#19930]

Fixes

• Fixed an issue where the hazelcast.yaml file was ignored when it is the only configuration file present in the
  Hazelcast setup; during startup it was looking only for the hazelcast.xml file and producing an error message saying that
  the configuration does not exist even though there is the yaml configuration file. Now it automatically uses hazelcast.yaml
  when hazelcast.xml is not available. [#20004]

• Fixed an issue where the Hazelcast command line interfaces commands were outputting incorrect command names
  when you want to see their usages using the --help argument ([#20002]). For example, the command hz-start --help was outputting
  the following:

  Usage: hazelcast-start [-d]
  -d, --daemon Starts Hazelcast in daemon mode

instead of the following:

Usage: hz-start [-d]
  -d, --daemon   Starts Hazelcast in daemon mode

• Hazelcast was executing cluster wide operations when you query the state of a member using the health
  check endpoint - it was causing to kill all the members in a cluster; this issue has been fixed. [#19905]
• Fixed an issue where there were mismatching map configurations when phone home is enabled. [#19900]
• Fixed an issue where the command hz-stop --help was not displaying the help but executing
  the hz-stop command. [#19726]
• Hazelcast's memcached implementation was interpreting the number values and parameters
  for incr and decr wrongly (numbers were being converted into byte arrays instead of decimals).
  This has been fixed by making these commands' implementations strictly follow the
  memcached protocol specification. [#19677]
• Fixed an issue where the totalPublishes statistics for the Reliable Topic data structure
  were always generated as 0. [#19651]
• When you both enable the persistence and automatic removal of stale data in the configuration,
  member startup failures were occurring. This has been fixed by adding the auto-remove-stale-data
  element to the configuration schema. [#19373]

Contributors

We would like to thank the contributors from our open source community
who worked on this release:

• Chelsea31: https://github.com/Chelsea31

v4.2.3

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.2.3 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Enhancements

For the distributions packages of IMDG, we updated the vulnerable version of log4j2 in Management Center to 2.15.0. No changes were made to the IMDG code.

v4.1.7

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.1.7 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Enhancements

For the distributions packages of IMDG, we updated the vulnerable version of log4j2 in Management Center to 2.15.0. No changes were made to the IMDG code.

v4.0.4

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.0.4 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Enhancements

For the distributions packages of IMDG, we updated the vulnerable version of log4j2 in Management Center to 2.15.0. No changes were made to the IMDG code.

v4.1.6

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.1.6 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Enhancements

• Improved the log message that is displayed when using the hazelcast.io.selectorMode
  property to decrease the high CPU usage. The previous misleading message read as
  "Recreated Selector because of possible java/network stack bug". It has been changed
  to "Selector was rebuilt, consider updating Java and/or your network stack drivers". [#19761]
• Introduced the hazelcast.internal.map.expired.key.scan.timeout.nanos property
  to limit the execution time of the cleanup operations, i.e., entry expiration tasks of a map;
  this is to prevent the increased CPU usage as the partition size grows. [#19663]

Fixes

• Hazelcast was executing cluster wide operations when you query
  the state of a member using the health check endpoint - it was causing to kill all the members
  in a cluster; this issue has been fixed. [#19837]
• The increment command (incr) in the Memcache client
  was returning the ASCII code of the expected result; this interpretation
  issue has been fixed. [#19681]

v5.0

This document lists the new features, enhancements, fixed issues and, removed
or deprecated features for Hazelcast 5.0 release. The numbers in the square
brackets refer to the issues in Hazelcast's GitHub repository.

Hazelcast 5.0 is a major release which unifies
the former Hazelcast IMDG and Jet products in a
single solution. The changes are summarized below.

For information about upgrading from previous IMDG and Jet
releases, see the Upgrade chapter in https://docs.hazelcast.com/hazelcast/5.0/.

To learn about the changes in previous IMDG and Jet releases, see https://docs.hazelcast.org/docs/rn/ and
https://jet-start.sh/blog/.

New Features

• Jet Streaming Engine: Hazelcast now incorporates the streaming engine, which was formerly and separately known as Hazelcast Jet.

• SQL Engine: We have added the support of following operators to our SQL engine:
  ** INSERT
  ** UPDATE
  ** DELETE
  ** ORDER BY
  ** GROUP BY
  ** JOIN
  ** CASE
  See https://docs.hazelcast.com/hazelcast/5.0/sql/sql-overview.html.
  Related issue and PRs: [#18940], [#18910], [#18898], [#18734],
  [#18663], [#18569], [#18479], [#18483], [#18422], [#18067]

• Persistence: This allows individual members and whole clusters to recover
  faster by persisting map entries and JCache data on disk. Members can use persisted data to recover during restarts.
  See https://docs.hazelcast.com/hazelcast/5.0/storage/persistence.html.

• Compact Serialization Format (Preview Feature): We have introduced a new serialization format
  (CompactSerializer), which is in its beta stage currently. This format requires much
  less storage space, provides better latency and throughput, and supports more extensive type sets:
  ** It supports schema evolution of a class and does not require any version to be specified explicitly.
  ** On common use cases where the field types of an object are natively supported via this compact format,
  Java DTO classes are automatically serialized without requiring a serializer (CompactSerializer) to be implemented.
  ** Your classes do not need to implement an interface like Portable. Once you enable the compact serialization,
  the classes not matching to any other serialization methods are serialized in this new format.

  See the https://docs.hazelcast.com/hazelcast/5.0/serialization/compact-serialization.html.
  Related PR: [#19017]

• Security for Jet Engine Jobs: The Jet engine allows you to upload custom code as well as access data
  outside of Hazelcast such as files on the device that's running a member. You can secure your Hazelcast member
  against malicious uses of the Jet API. See https://docs.hazelcast.com/hazelcast/5.0/pipelines/job-security.html.

Breaking Changes

API Changes

• For Google Cloud Storage (GCS) file sources, the SecuredFunction interface now returns a list of permissions instead of a single
  permission. Previously, Hazelcast was returning only the permission for the bucket to be read, and this was causing a source to be
  possibly exploited for gaining information whether some file exists in the system. Now, Hazelcast also returns a permission
  for the keyfile that is required to read a bucket on GCS. [#19407]

• The "Hot Restart Persistence" feature name has been changed to "Persistence"; with this change
  we've performed various cleanups in its API:
  ** The HotRestartService has been deprecated; see <<removed-deprecated-features, Deprecated Features>>.
  ** Renamed com.hazelcast.hotrestart.BackupTask as com.hazelcast.persistence.BackupTask.
  ** Renamed com.hazelcast.hotrestart.BackupTaskState as com.hazelcast.persistence.BackupTaskState.
  ** Added the isBackupEnabled() to PersistenceService/HotRestartService that does
  not have a default implementation.
  [#19404]

• After the unification of cloud discovery plugins (see the Cloud Discovery Plugins section below),
  the exception class for the failure in generating SSLSocketFactory is changed from
  KubernetesClientException to RestClientException for the Kubernetes plugin. [#19132]

• Changed the type of YEAR field in the SQL client protocol from short to int. [#18984]

• Since the HOST and RACK metadata were deprecated in the previous Hazelcast
  release, these information are removed from the ZONE_AWARE partition grouping
  configuration. [#18780]

• Since DAG printing was not reflecting the real queue size, the DAG.toDotString(int defaultParallelism) method
  signature is changed as DAG.toDotString(int defaultLocalParallelism, int defaultQueueSize). You, now, need to supply the
  queue size that will be shown if it is not overriden on the edge. [#18475]

Configuration Changes

• Removed the following properties that were used in the former Jet product, since it
  is now part of Hazelcast 5.0:
  ** jet.home
  ** jet.imdg.version.mismatch.check.disabled
  [#18999]

Enhancements

Distribution

• Hazelcast distribution is now available in two versions: full and slim.
  While the full one includes Hazelcast and all of its modules along with SQL,
  Jet engine extensions and Management Center, the slim one only includes the Hazelcast
  runtime, default configurations and scripts.
  See https://docs.hazelcast.com/hazelcast/5.0/migrate/upgrading-from-imdg-4.html#changes-in-distribution-packaging
  for details. [#18990], [#18989]
• Consolidated the scripts delivered with the former IMDG and Jet distributions.
  See https://docs.hazelcast.com/hazelcast/5.0/migrate/upgrading-from-imdg-4.html#changes-in-distribution-packaging. [#18999]
• The former hazelcast-sql, hazelcast-sql-core and hazelcast-jet-sql Maven modules in the distributions
  have been merged into a single hazelcast-sql module as a part of the Hazelcast 5.0 distribution. [#18584]
• Removed the jackson-core dependency from pom.xml since it was
  breaking the extensions that depend on jackson. [#18665]
• Moved the former Hazelcast Jet code samples into the
  https://github.com/hazelcast/hazelcast-code-samples repository. [#475]

The Jet and SQL Engine

• Added support of rolling upgrades for SQL. [#19026]
• Added support of reading data from High-Density Memory Store backed maps via the SQL engine. [#19328]
• Added support of regular and index (migration tolerant) scan of High-Density Memory Store via SQL. [#19227]
• Tables were called mapping in information_schema.mappings and table in information_schema.columns.
  This inconsistency has been fixed by renaming mapping as table. [#19210]
• Added support of the CONCAT_WS function, which takes variable sized
  VARCHAR (minimum 3) and returns a VARCHAR that consists of the
  concatenation of the arguments except the first one using the first argument as a separator. [#19094]
• The 'SELECT' statement now also supports queries without the FROM clause
  so that you can submit queries like SELECT rand() without this clause. [#19030]
• The Jet engine jobs submitted in a Hazelcast cluster are now cancelled
  when you upgrade your Hazelcast version since the Jet engine doesn't provide backwards compatibility. [#19012]
• Implemented the partition-tolerant index scan processor for Hazelcast maps:
  during a partition migration, this processor searches all the migrated partitions on all
  available cluster members. [#18968]
• Added support of the putIfAbsentAsync() method for maps on the member side;
  which is required for the usage of INSERT INTO statements in SQL queries. [#18946]
• Added support of returning nested fields without having to
  deserialize them, which enables you to use Portable in client/server
  deployments without touching the server side; for example, SQL queries
  can now return columns without having the class on the server-side classpath. [#18922]
• Standardized the TIME and TIMESTAMP temporal formats for the
  SQL engine: You can now use TIME without leading zeroes and TIMESTAMP
  with space instead of the T symbol. Also added support of leading non-zero
  characters for the DATE formats. [#18881], [#18842]
• Added support of OFFSET for SQL queries. [#18866]
• Implemented IdentifiedDataSerializable for SQL schema objects. [#18851]
• Changed the since tags in Jet engine API and its extension modules
  from @since x.y to @since Jet x.y. [#18832]
• Implemented the OnHeapMapScanP class to read the Hazelcast maps directly
  by the SQL engine. [#18685]
• Implemented a basic memory management for the SQL engine
  so that number of records accumulated by it can be limited
  to avoid out of memory failures. You can use the max-processor-accumulated-records
  configuration element for this purpose. [#18671]
• Added support of dynamic parameters for the SQL engine and file table functions. [#18613], [#18522]
• Introduced QueryDataType.MAP and QueryDataTypeFamily.MAP to support map operand checks
  for file table functions. [#18602]
• Added support of EXTRACT(field FROM source) for the SQL engine.
  The function computes date parts from the source field. The supported types for source argument are as follow:
  ** Date
  ** Time
  ** Timestamp
  ** Timestamp With Time Zone
  [#18570]
• Added support of the LIMIT <n> and ORDER BY clauses for the streaming engine. [#18479]
• Implemented the following functions for the SQL engine:
  ** REPLACE
  ** ATAN2
  ** POWER
  ** SQUARE
  ** SQRT
  ** CBRT
  ** POSITION
  ** COALESCE
  ** NULLIF
  ** TO_EPOCH_MILLIS
  ** TO_TIMESTAMP_TZ
  [#18900], [#18856], [#18510], [#18487], [#18450], [#18424], [#18405]
• Added support of plan caching for Jet engine based queries. [#18446]
• Added support of plus and minus operations for interval types (date, time, etc.) for
  the SQL engine. [#18390]
• Added support of various new Portable types for the SQL engine. [#18115]
• Added support of IN and BETWEEN operators for the SQL queries. [#18483], [#18422], [#18067]

Data Structures

• The previous Replicated Map implementation was iterating all the values
  while calculating the size of map; ...

v4.1.5

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.1.5 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Fixes

• Fixed an issue where a high amount of garbage collection pressure was occurring
  during repartitioning especially when having a high partition count. [#19295]
• Fixed an issue where the client state listener was not properly working
  with failover clients (in blue-green deployments); it was failing with
  invalid configuration exception. [#19116]

Deprecated/Removed Features

• Deprecated the following properties:
  ** hazelcast.client.statistics.period.seconds
  ** hazelcast.client.statistics.enabled

v4.2.2

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 4.2.2 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Fixes

• Fixed an issue where the client state listener was not properly working
  with failover clients (in blue-green deployments); it was failing with
  invalid configuration exception. #19115

v5.0-BETA-2

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast IMDG 3.12 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

==== 3.12 ====

1. Breaking Changes

• Support for JDK 6 and 7 has been dropped. The minimum Java version that Hazelcast supports now is Java 8. See the Supports JVMs section.

2. New Features

Hazelcast IMDG Enterprise New Features:

• Blue-Green and Disaster Recovery for Java Clients: Introduced the support for Hazelcast Java clients to switch between alternative clusters. See the Blue Green Deployment and Disaster Recovery section.

Hazelcast IMDG Open Source New Features:

• CP Subsystem: Implementing the https://raft.github.io/[Raft consensus algorithm], Hazelcast introduces its CP subsystem which runs within a Hazelcast cluster and offers linearizable implementations of Hazelcast's concurrency APIs. See the CP Subsystem chapter.
• Querying JSON Strings: You can now query JSON strings stored inside your Hazelcast clusters. See the Querying JSON Strings section.
• Pipelining: Introduced pipelining mechanism using which you can send multiple requests in parallel to Hazelcast members or clients, and read the responses in a single step. See the Pipelining section.
• Support for Multiple Endpoints When Configuring Member’s Networking: Added the ability to configure the Hazelcast members with separate server sockets for different protocols. See the Advanced Network Configuration section.
• YAML Configuration Support: Added the support for configuring Hazelcast in YAML. See the Configuring Declaratively with YAML section.

3. Enhancements

Hazelcast IMDG Enterprise Enhancements:

• Sharing Hot Restart base-dir among Multiple Members: The base directory for the Hot Restart feature (base-dir) is now used as a shared directory between multiple members, and each member uses a unique sub-directory
  inside this base directory. This allows using the same configuration on all the members. Previously, each member had to use a separate directory which complicated the deployments on cloud-like environments. During the restart, a member tries to lock an already existing Hot Restart directory inside the base directory. If it cannot acquire any, then it creates a fresh new directory. See the Configuring Hot Restart section.
• Lower Latencies and Higher Throughput in WAN Replication: Improved the design of the WAN replication mechanism to allow configuring it for lower latencies and higher throughput. See the Tuning WAN Replication For Lower Latencies and Higher Throughput section.
• Add/Remove WAN Publishers in a Running Cluster: Introduced the ability to dynamically add or remove WAN publishers (target clusters). See the Dynamically Adding WAN Publishers section.
• Automatic Removal of Stale Hot Restart Data: Introduced an option that allows the stale Hot Restart data to be removed automatically. See the description of the auto-remove-stale-data configuration element in the Configuring Hot Restart section.
• Client Permission Handling When a New Member Joins: Introduced a declarative configuration attribute on-join-operation for the client permission in the Security configuration (its programmatic configuration equivalent is the setOnJoinPermissionOperation() method). This attribute allows to choose whether a new member joining to a cluster will apply the client permissions stored in its own configuration, or will use the ones defined in the cluster. See the Handling Permissions When a New Member Joins section.
• Automatic Cluster Version Change after a Rolling Upgrade: Introduced the ability to automatically upgrade the cluster version after a rolling upgrade. See the Upgrading Cluster Version section.
• FIPS 140-2 Validation: Hazelcast now can be configured to use a FIPS 140-2 validated module. See the FIPS 140-2 section.

Hazelcast IMDG Open Source Enhancements:

• Client Instance Names and Labels: You can now retrieve the names of client instances on the member side. Moreover, client labels have been introduced so that you can group your clients and/or perform special operations for specific clients. See the Defining Client Labels section.
• Composite Indexes: Introduced the ability to recognize the queries that use all the indexed properties and treat them as a composite, e.g., foo = 1 and bar = 2 and foobar = 3. See the Composite Indexes section.
• REST Endpoint Groups: With this enhancement you can enable or disable the REST API completely, Memcache protocol and REST endpoint groups. See the Using the REST Endpoint Groups section.

The following are the other improvements performed to solve the enhancement issues opened by the Hazelcast customers/team.

• Improved the YAML configuration so that you can configure multiple WAN member sockets. [#14800]
• Members now fail fast when the max-idle-seconds element for the entries in a map is set to 1 second. See the note in the Configuring Map Eviction section for this element. [#14697]
• Removed group password from the Hazelcast’s default XML configuration file. Also improved the non-empty password INFO message. It's now only logged if security is disabled, password is not empty and password is not the Hazelcast default one. [#14603]
• Improved the code comments for the HazelcastInstance interface. [#14439]
• Improved the Javadoc of HazelcastClient so that the code comments now use "unisocket client" instead of "dumb client". [#14213]
• Added the ability to perform an LDAP subtree search for groups in Hazelcast Management Center’s LDAP authenticator. [#14118]
• Added the ability to set the EvictionConfig.comparatorClassName() in the client’s declarative configuration, too. [#14093]
• Introduced the /ready endpoint to the REST API to allow checking a member if it is ready to be used after it joins to the cluster. [#14089]
• Improved the syncing of XSD files. [#14070]
• The IMap.removeAll() method now supports PartitionPredicate. [#12238]
• Improved the diagnostics tool so that it automatically creates the configured directory for the diagnostic outputs. [#11946]

4. Fixes

• Fixed an issue where the state of member list on the clients were broken after a hot restart in the cluster. [#14839]
• Fixed an issue where the outbound pipeline was not waking up properly after merging the write-through changes. [#14830]
• Fixed an issue where a Hazelcast Java client was not able to connect to the cluster (which has the advanced-network configuration) after a split-brain syndrome is healed. [#14768]
• Fixed an issue where the like and ilike predicates didn’t catch any entity with the text field containing the '\n' character. [#14751]
• Fixed an issue where NullPointerExceptions was thrown recursively when a client is connected to an unreachable member during a split-brain. [#14722]
• Fixed an issue where Hazelcast running on RHEL (OpenJDK8) shows unknown gc in the logs, instead of major gc and minor gc. [#14701]
• Fixed an issue where the IP client selector was not working for the local clients. [#14654]
• Fixed the wording of a misleading error in the first attempt to connect to a wrongly configured cluster. The error message has been changed to “Unable to connect to any cluster”. https://github.com/hazelcast/hazelcast/issues/14574[[#14574]]
• Fixed an issue where a connection configured using AdvancedNetworkConfig was not denied correctly for some inappropriate endpoints. [#14532]
• Fixed the REST service which was not working when the REST endpoint is configured for AdvancedNetworkConfig. [#14516]
• Fixed an issue where the setAsync() method was throwing NullPointerException. [#14445]
• Fixed an issue where the collection attributes indexed with [any] were causing incorrect SQL query results, if the first data inserted to the map has no value for the attribute or the collection is empty. [#14358]
• Fixed an issue where mapEvictionPolicy couldn’t be specified in the JSON configuration file. [#14092]
• Fixed an issue where the rolling upgrade was failing when all members change their IP addresses. [#14088]
• Fixed an issue where the resources were not wholly cleared when destroying DurableExecutorService causing some resources to be left in the heap. [#14087]
• Fixed an issue where the REST API was not handling the HTTP requests without headers correctly: when a client sends an HTTP request without headers to the Hazelcast REST API, the HttpCommand class was wrongly expecting an additional new line. [#14353]
• Fixed an issue where QueryCache was not returning the copies of the found objects. [#14333]
• Fixed an issue where the MultiMap's RemoveOperation was iterating through the backing collection, which caused performance degradation (when using the SET collection type). [#14145]
• Fixed an issue where the user code deployment feature was throwing NullPointerException while loading multiple nested classes and using entry processors. [#14105]
• Fixed an issue where the newly joining members could not form a cluster when the existing members are killed. [#14051]
• Fixed an issue where the IMap.get() method was not resetting the idle time counter when read-backup-data is enabled. [#14026]
• Fixed an issue where the addIndex() method was performing a full copy of entries when a new member joins the cluster, which is not needed. [#13964]
• Fixed an issue where the initialization failure of discoveryService was causing some threads to remain open and the JVM could not be terminated because of these threads. [#13821]
• Fixed the discrepancy between the XSD on the website and the one in the download package. [#13011]
• PagingPredicate with comparator was failing to serialize when sending from the client or member when the cluster size is more than 1. This has been fixed by making the PagingPredicateQuery comparator s...

v5.0-BETA-1

This document lists the new features, enhancements, fixed issues and, removed or deprecated features for Hazelcast 5.0-BETA-1 release. The numbers in the square brackets refer to the issues in Hazelcast's GitHub repositories.

Hazelcast 5.0 will be a major release which unifies the former Hazelcast IMDG and Jet products in a single solution. The changes are summarized below.

For information on upgrading from previous IMDG and Jet releases, see the "Migrate to this Version" chapter of Hazelcast documentation.

To learn about the changes in previous IMDG and Jet releases, see https://docs.hazelcast.org/docs/rn/ and
https://jet-start.sh/blog/[Jet release notes].

New Features

• SQL Engine: We have added the support of following operators to our SQL engine:
  ** INSERT
  ** UPDATE
  ** DELETE
  ** ORDER BY
  ** GROUP BY
  ** JOIN
  ** CASE
  [#18940], [#18910], [#18946], [#18569], [#18479], [#18483], [#18422], [#18067]

• Compact Serialization Format (Preview Feature): We have introduced a new serialization format
  (CompactSerializer), which is in its beta stage currently. This format requires much
  less storage space, provides better latency and throughput, and supports more extensive type sets:
  ** It supports schema evolution of a class and does not require any version to be specified explicitly.
  ** On common use cases where the field types of an object are natively supported via this compact format,
  Java DTO classes are automatically serialized without requiring a serializer (CompactSerializer) to be implemented.
  ** Your classes do not need to implement an interface like Portable. Once you enable the compact serialization,
  the classes not matching to any other serialization methods are serialized in this new format.
  [#19017]

• Merkle Tree for ICache: Like Hazelcast maps, now caches (ICache) also support
  the Delta WAN Synchronization using Merkle trees. [#18898]

Breaking Changes

BETA API Changes

• Changed the type of YEAR field in the SQL client protocol from short to int. [#18984]
• Since the HOST and RACK metadata were deprecated in the previous Hazelcast
  release, these information are removed from the ZONE_AWARE partition grouping
  configuration. [#18780]
• Since DAG printing was not reflecting the real queue size, the DAG.toDotString(int defaultParallelism) method
  signature is changed as DAG.toDotString(int defaultLocalParallelism, int defaultQueueSize). You, now, need to supply the
  queue size that will be shown if it is not overriden on the edge. [#18475]

Configuration Changes

• Removed the following properties that were used in the former Jet product, since it
  is now part of Hazelcast 5.0:
  ** jet.home
  ** jet.imdg.version.mismatch.check.disabled
  [#18999]

Enhancements

Distribution

• Hazelcast distribution is now available in two versions: full and slim.
  While the full one includes Hazelcast and all of its modules along with SQL,
  Jet engine extensions and Management Center, the slim one only includes the Hazelcast
  runtime, default configurations and scripts.
  for details. [#18990], [#18989]
• Consolidated the scripts delivered with the former IMDG and Jet distributions.
  See the Changes in Distribution Packaging section. [#18999]
• The former hazelcast-sql, hazelcast-sql-core and hazelcast-jet-sql Maven modules in the distributions
  have been merged into a single hazelcast-sql module as a part of the Hazelcast 5.0 distribution. [#18584]
• Removed the jackson-core dependency from pom.xml since it was
  breaking the extensions that depend on jackson. [#18665]
• Moved the former Hazelcast Jet code samples into the Hazelcast code samples repository. [#475]

The Jet and SQL Engine

• The Jet engine jobs submitted in a Hazelcast cluster are now cancelled
  when you upgrade your Hazelcast version since the Jet engine doesn't provide backwards compatibility. [#19012]
• Added support of the putIfAbsentAsync() method for maps on the member side;
  which is required for the usage of INSERT INTO statements in SQL queries. [#18946]
• Added support of returning nested fields without having to
  deserialize them, which enables you to use Portable in client/server
  deployments without touching the server side; for example, SQL queries
  can now return columns without having the class on the server-side classpath. [#18922]
• Standardized the TIME and TIMESTAMP temporal formats for the
  SQL engine: You can now use TIME without leading zeroes and TIMESTAMP
  with space instead of the T symbol. Also added support of leading non-zero
  characters for the DATE formats. [#18881], [#18842]
• Added support of OFFSET for SQL queries. [#18866]
• Changed the since tags in Jet engine API and its extension modules
  from @since x.y to @since Jet x.y. [#18832]
• Implemented the OnHeapMapScanP class to read the Hazelcast maps directly
  by the SQL engine. [#18685]
• Implemented a basic memory management for the SQL engine
  so that number of records accumulated by it can be limited
  to avoid out of memory failures. You can use the max-processor-accumulated-records
  configuration element for this purpose. [#18671]
• Added support of dynamic parameters for the SQL engine and file table functions. [#18613], [#18522]
• Introduced QueryDataType.MAP and QueryDataTypeFamily.MAP to support map operand checks
  for file table functions. [#18602]
• Added support of EXTRACT(field FROM source) for the SQL engine.
  The function computes date parts from the source field. The supported types for source argument are as follow:
  ** Date
  ** Time
  ** Timestamp
  ** Timestamp With Time Zone
  [#18570]
• Added support of the LIMIT <n> clauses for the streaming engine. [#18479]
• Implemented the following functions for the SQL engine:
  ** REPLACE
  ** ATAN2
  ** POWER
  ** SQUARE
  ** SQRT
  ** CBRT
  ** POSITION
  ** COALESCE
  ** NULLIF
  ** TO_EPOCH_MILLIS
  ** TO_TIMESTAMP_TZ
  [#18900],[#18856], [#18510], [#18487], [#18450], [#18424], [#18405]
• Added support of plan caching for Jet engine based queries. [#18446]
• Added support of plus and minus operations for interval types (date, time, etc.) for
  the SQL engine. [#18390]
• Added support of various new Portable types for the SQL engine. [#18115]
• Added support of IN and BETWEEN operators for the SQL queries. [#18483], [#18422], [#18067]

Serialization

• Added support of default serializers for the following classes
  which has been necessary for non-Java clients to use these:
  ** LocalDate
  ** LocalTime
  ** LocalDateTime
  ** OffsetDatetime
  [#18983]

Security

• Introduced the simple authentication configuration; it allows to have users and
  their assigned roles stored together with other Hazelcast configurations. See the example [#18948]:

hazelcast:
security:
enabled: true
realms:
- name: simpleRealm
authentication:
simple:
users:
- username: test
password: 'a1234'
roles:
- monitor
- hazelcast
- username: root
password: 'secret'
roles:
- admin

Configuration

• Added a configuration option to enable/disable resource uploading for
  Jet engine jobs.
• Even when the factory configuration is missing on the member but
  the map is configured to have the the in-memory format as OBJECT, Hazelcast now can store
  portables as PortableGenericRecord and still query them
  without needing to convert them to Object/Data. [#18891]
• Introduced the following properties:
  ** hazelcast.partition.rebalance.mode: It determines whether cluster
  membership change triggers partition rebalancing automatically (auto) or
  explicit action is required for rebalancing to occur (manual). Its default is auto.
  ** hazelcast.partition.rebalance.delay.seconds: it specifies the time in seconds
  to wait before triggering automatic partition
  rebalancing after a member leaves the cluster unexpectedly. Unexpectedly in this
  context means that a member leaves the cluster by programmatic termination, a
  process crash or network partition. Its default is 0, which means rebalancing is
  triggered immediately.
  [#18425]

Other Enhancements

• Added the client console entry point to the Hazelcast command line
  interface; you can now use the hazelcast console command to start
  the client console application. [#18857]
• Enhanced the getPartitionGroupStrategy() method to have cluster members
  as arguments so that useful partitioning strategies can be implemented by accessing
  the members using this method. [#18794]
• The log message for infinite cluster connection timeout is clearer now.
  Previously, it was represented as the value of Long.MAX_VALUE. [#18642]
• Introduced a new mechanism in the background expiration tasks;
  now a thread local array controls the allocations for these tasks otherwise
  which may cause increased garbage collection pressure and CPU usage spikes when
  you use aggressive expiration configurations, e.g., low time-to-live values. [#18633]
• The license key is, now, not shown while starting a member on Docker with overriding configurations. [#18568]
• Limited the number of parallel partition reads (to a fixed value of five)
  for maps and caches to prevent out of memory failures. [#18663], [#18499]
• Added a comprehensive documentation for metrics produced by Hazelcast.
  See https://docs.hazelcast.com/imdg/5.0/list-of-hazelcast-metrics.html[here]
  for the full list of metrics with their descriptions. [#17880]
• Improved the speed of connection by a member when it joins the cluster, by
  removing the unnecessary sleep statements in the code. [#17428]

== Fixes

• SQL expressions now does not fail when used with trailing semicolons. [18976]
• Fixed an issue where the health monitor was incorrectly showing the value for
  free metadata memory. [#...