[mongodb-dev] MongoDB 4.0 Released

[Eliot Horowitz]

*MongoDB 4.0 <https://www.mongodb.com/mongodb-4.0> is now generally
available for production deployments. This release offers the best way to
work with data, to intelligently place it where you need it, and the
freedom to run anywhere. It serves all your operational, transactional, and
real-time analytics workloads. Download MongoDB
<https://www.mongodb.com/download-center#production> today, or try MongoDB
4.0 in the cloud with Atlas <https://www.mongodb.com/cloud/atlas> in
minutes.We are also announcing the release of Ops Manager 4.0 and Compass
1.14.0, accessible via our download center
<https://www.mongodb.com/download-center?filter=enterprise#ops-manager>.
Compass 1.14.0 introduces the Aggregation Pipeline Builder
<https://docs.mongodb.com/compass/manual/aggregation-pipeline-builder/>extending
the MongoDB Compass point and click visual query editor to enable
developers and business analysts to construct sophisticated processing
pipelines that transform, aggregate, and analyze MongoDB data, all from a
simple GUI. In addition, we’re pleased to announce the public beta of
MongoDB Charts <https://www.mongodb.com/products/charts>. MongoDB Charts is
designed to natively handle MongoDB’s rich data structures, making it easy
to visualize complex arrays and subdocuments without flattening the data or
spending time and effort on ETL. As an integrated tool, it connects
directly to MongoDB so that your visualizations are created on live data,
ensuring that you always have the most up-to-date view. For more
information about MongoDB 4.0, please see the following resources:​ - ​Read
the What's New In MongoDB 4.0 white paper
<https://www.mongodb.com/collateral/mongodb-40-whats-new>- Get up to speed
on MongoDB with the MongoDB 4.0 Online Course
<https://university.mongodb.com/courses/M040/about>- ​Review the MongoDB
4.0 Release Notes <http://docs.mongodb.org/manual/release-notes/4.0>​
<https://docs.mongodb.com/manual/release-notes/3.6>- ​Try MongoDB 4.0 in
Atlas <https://www.mongodb.com/cloud/atlas> in minutes​MongoDB 4.0 includes
many exciting new features. Here are some of the highlights:Multi-document
ACID transactionsWith snapshot isolation and all-or-nothing execution,
transactions extend MongoDB ACID data integrity guarantees to multiple
documents across one or many collections. These feel just like the
transactions you are familiar with from relational databases, are easy to
add to any application that needs them, and do not impact the performance
of workloads that don’t require them. With multi-document transactions it’s
easier than ever for all developers to address a complete range of use
cases with MongoDB, while for many of them, simply knowing that they are
available will provide critical peace of mind. In MongoDB 4.0 transactions
work across replica sets, and MongoDB 4.2 will support transactions across
sharded clusters.Snapshot Read ConcernTaking advantage of the transactions
infrastructure introduced in MongoDB 4.0, the new snapshot read concern
<https://docs.mongodb.com/manual/reference/read-concern-snapshot/> ensures
queries and aggregations executed within a read-only transaction will
operate against a single, isolated snapshot on the primary replica. As a
result, a consistent view of the data is returned to the client,
irrespective of whether that data is being simultaneously modified by
concurrent operations. Snapshot reads are especially useful for operations
that return data in batches with the `getMore`command.Non-Blocking
Secondary Reads To ensure that reads could not return data that was not in
the same causal order as the primary replica, MongoDB previously blocked
secondary reads while oplog entries were applied. MongoDB 4.0 avoids
blocking by reading from a snapshot on the secondary, improving read
latencies and increasing throughput from the replica set, while maintaining
a consistent ordering of data. For replica sets with a high write load, not
having to wait for readers between applying oplog batches allows for
reduced replication lag and faster confirmation of majority
writes.Extensions to Change StreamsChange Streams can now be configured
track changes across an entire database or whole cluster. Additionally,
change streams now will return a cluster time associated with an event,
which can be used by the application to provide an associated wall clock
time for the event.Data Type ConversionsA $convert
<https://docs.mongodb.com/manual/reference/operator/aggregation/convert/>
expression has been added to the aggregation framework. This will not only
allow new ETL workloads and simplify app development, but also allow the
MongoDB BI Connector <https://www.mongodb.com/products/bi-connector> to
push down large amounts of work to MongoDB Server, unlocking significantly
improved performance for users of this connector.Improved Migrations
ThroughputSharded migrations are now up to 40% faster, so users can more
easily and quickly scale capacity elastically in response to changing
application demand as nodes are added and removed from sharded
clusters.SCRAM-SHA-256We’ve added support for SCRAM-SHA-256, allowing
individual users to store SHA-2 based credentials when security policies
disallow the use of SHA-1.Native TLSOn macOS and Windows, MongoDB now uses
the platform's native cryptography and TLS support, and no longer uses
OpenSSL. Additionally, the system certificate stores can be used to manage
certificates.Improved Sharded Operation ManagementOperators can now list
and kill queries
<https://docs.mongodb.com/manual/reference/operator/aggregation/currentOp/#pipe._S_currentOp>
running in a sharded cluster directly on a mongos node. When a sharded
query either encounters an operation-fatal error, or is explicitly killed
by an operator, on either mongos or any shard, the query will be promptly
terminated on all other shards in the cluster.Slow Query Logging on
mongosPreviously only available on mongod, we now log operations which
exceed a particular latency threshold on mongos, enabling DBAs to more
quickly identify problematic queries.Hybrid Cursor CachingImprovements in
cursor caching unlock up to 2x performance gains on deployments running
with a large number of collections, and enable operations like dropping a
collection to execute without causing any performance degradation on other
active collections.Download the latest drivers
<https://docs.mongodb.com/ecosystem/drivers/> to take advantage of these
new features. See the Driver compatibility matrix
<https://docs.mongodb.com/ecosystem/drivers/driver-compatibility-reference/>
for the full list of languages supporting MongoDB 4.0.For community users,
MongoDB 4.0 adds a free monitoring cloud service, available wherever they
run their databases. You can opt in and out of the service at any time
directly from the MongoDB shell. With monitoring enabled, metrics collected
by the serverStatus command are visualized by the MongoDB cloud GUI,
accessed from a simple URL. Replica set configuration, memory, network, and
disk usage, the status of active connections and logical sessions, page
faults, locks, ops counters, query latency, TLS certificate lifecycles, and
more are accessible. You can quickly assess database health and optimize
performance, all from the convenience of a powerful browser-based GUI.
Last but not least, we would like to acknowledge the following community
members who have contributed to this release: Aidan SE Mahler, Alexander
Paderin, Alon Horev, Andrei Belashou, Andrew Stiegmann, Antoine Hom, Artem,
Benoit Bui, Calvin Sze, CenZheng, Chibuikem Amaechi, Clive Hill, Dandan
Lin, Daniel Stewart, David Bartley, Dmitri Shubin, Emmanuel Cagadas, Fox
Lady, Gianfranco Palumbo, Gianluca De Cicco, Jelle van der Waa, Jozef
Dobos, Juan Paulo Gutierrez, Juergen Zimmermann, Jun He, Keita Akutsu,
Kevin Cybura, Maia Fox, Manuel, Marek SkalickÜ, Matthew Kruse, Max Allan,
Michael Jansen, Naveen, Olav Morken, Oleg Rekutin, Paco, Paderin Aleksandr,
Patrik Laszlo, Peter Ahlers, Praveen Arkeri, Sergei Turchanov, Sergio
Maruki, Simone Maratea, Tim Niemueller, Tomislav Plavcic, Xavier Del
Castillo, Yuriy, atish, lang qiu, ppqtyq, and simon hall -- as well as over
three thousand 4.0 beta testers. Thank you!Please continue sending us your
feedback!Thanks,The MongoDB Team*