@@ -24,18 +24,18 @@ Transactions
2424 :class: twocols
2525
2626.. meta::
27- :description: For situations that require atomicity of reads and writes to multiple documents (in a single or multiple collections), MongoDB supports multi-document transactions.
27+ :description: For situations that require atomicity of reads and writes to multiple documents (in a single or multiple collections), MongoDB supports multi-document transactions, also called distributed transactions .
2828 :keywords: MongoDB, transactions, distributed transactions, MongoDB multi-document transactions, MongoDB multi-statement transactions, java transaction examples, python transaction examples, node transaction examples, php transaction examples, scala transaction examples, csharp transaction examples, perl transaction examples, ruby transaction examples
2929
3030In MongoDB, an operation on a single document is atomic. Because you can
3131use embedded documents and arrays to capture relationships between data
3232in a single document structure instead of normalizing across multiple
3333documents and collections, this single-document atomicity obviates the
34- need for multi-document transactions for many practical use cases.
34+ need for distributed transactions for many practical use cases.
3535
3636For situations that require atomicity of reads and writes to multiple
3737documents (in a single or multiple collections), MongoDB supports
38- multi-document transactions. With distributed transactions,
38+ distributed transactions. With distributed transactions,
3939transactions can be used across multiple operations, collections,
4040databases, documents, and shards.
4141
@@ -288,32 +288,10 @@ upper-right to set the language of the following example.
288288Transactions and Atomicity
289289--------------------------
290290
291- .. note :: Distributed Transactions and Multi-Document Transactions
291+ .. include :: /includes/transactions/distributed-transaction-repl-shard-support.rst
292292
293- Starting in MongoDB 4.2, the two terms are synonymous. Distributed
294- transactions refer to multi-document transactions on sharded
295- clusters and replica sets. Multi-document transactions (whether on
296- sharded clusters or replica sets) are also known as distributed
297- transactions starting in MongoDB 4.2.
298-
299- For situations that require atomicity of reads and writes to multiple
300- documents (in a single or multiple collections), MongoDB supports
301- multi-document transactions:
302-
303- - **In version 4.0**, MongoDB supports multi-document transactions on
304- replica sets.
305-
306- - **In version 4.2**, MongoDB introduces distributed transactions,
307- which adds support for multi-document transactions on sharded
308- clusters and incorporates the existing support for
309- multi-document transactions on replica sets.
310-
311- To use transactions on MongoDB 4.2 deployments (replica sets and
312- sharded clusters), clients :red:`must` use MongoDB drivers updated for
313- MongoDB 4.2.
314-
315- Multi-document transactions are atomic (i.e. provide an
316- "all-or-nothing" proposition):
293+ Distributed transactions are atomic. They provide an "all-or-nothing"
294+ proposition:
317295
318296- When a transaction commits, all data changes made in the transaction
319297 are saved and visible outside the transaction. That is, a transaction
@@ -339,7 +317,7 @@ Transactions and Operations
339317---------------------------
340318
341319Distributed transactions can be used across multiple operations,
342- collections, databases, documents, and, starting in MongoDB 4.2, shards.
320+ collections, databases, documents, and shards.
343321
344322For transactions:
345323
@@ -359,19 +337,15 @@ For a list of operations not supported in transactions, see
359337Create Collections and Indexes In a Transaction
360338~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
361339
362- Starting in MongoDB 4.4, you can perform the following operations inside
363- of a :ref:`multi-document transaction <transactions>` as long as
364- the transaction is not a cross-shard write transaction:
340+ You can perform the following operations inside of a :ref:`distributed
341+ transaction <transactions>` as long as the transaction is not a
342+ cross-shard write transaction:
365343
366344- Create collections.
367345
368346- Create indexes on new empty collections created earlier in the same
369347 transaction.
370348
371- In MongoDB 4.2 and earlier, operations that affect the database catalog,
372- such as creating or dropping a collection or an index, are
373- :red:`disallowed` in transactions.
374-
375349When creating a collection inside a transaction:
376350
377351- You can :ref:`implicitly create a collection
@@ -470,8 +444,7 @@ Restricted Operations
470444Transactions and Sessions
471445-------------------------
472446
473- - Transactions are associated with a session; i.e. you start a
474- transaction for a session.
447+ - Transactions are associated with a session
475448
476449- At any given time, you can have at most one open transaction for a
477450 session.
@@ -549,20 +522,17 @@ Transactions support the following read concern levels:
549522``"majority"``
550523``````````````
551524
552- - Read concern :readconcern:`"majority"` returns data that has been
553- acknowledged by a majority of the replica set members (i.e. data
554- cannot be rolled back) **if** the transaction commits with
555- :ref:`write concern "majority" <transactions-write-concern>`.
556-
557- - If the transaction does not use :ref:`write concern "majority"
558- <transactions-write-concern>` for the commit, the
559- :readconcern:`"majority"` read concern provides **no** guarantees that
560- read operations read majority-committed data.
525+ - If the transaction commits with :ref:`write concern "majority"
526+ <transactions-write-concern>`, read concern :readconcern:`"majority"`
527+ returns data that has been acknowledged by a majority of the replica
528+ set members and can't be rolled back. Otherwise, read concern
529+ :readconcern:`"majority"` provides no guarantees that read operations
530+ read majority-committed data.
561531
562- - For transactions on sharded cluster, :readconcern:`"majority"` read
563- concern cannot guarantee that the data is from the same snapshot
564- view across the shards. If snapshot isolation is required, use
565- :ref:`transactions-read-concern-snapshot` read concern .
532+ - For transactions on sharded cluster, read concern
533+ :readconcern:`"majority"` can't guarantee that the data is from the
534+ same snapshot view across the shards. If snapshot isolation is
535+ required, use read concern :ref:`transactions-read-concern-snapshot`.
566536
567537.. _transactions-read-concern-snapshot:
568538
@@ -616,7 +586,7 @@ You can set the transaction-level :doc:`write concern
616586 <replica-set-arbiter-configuration>`. See
617587 :ref:`wc-default-behavior`.
618588
619- - :writeconcern:`w: 1 <\<number\>>` in MongoDB 4.4 and earlier.
589+ - :writeconcern:`w: 1 <\<number\>>`
620590
621591.. seealso::
622592
@@ -652,7 +622,7 @@ values, including:
652622
653623- Write concern :writeconcern:`w: "majority" <"majority">` returns
654624 acknowledgement after the commit has been applied to a majority
655- (M) of voting members; i.e. the commit has been applied to the
625+ (M) of voting members, meaning the commit has been applied to the
656626 primary and (M-1) voting secondaries.
657627
658628- When you commit with :writeconcern:`w: "majority" <"majority">`
@@ -749,7 +719,7 @@ MongoDB provides various transactions metrics:
749719
750720 * - :binary:`~bin.mongod` and :binary:`~bin.mongos` log messages
751721
752- - Includes information on slow transactions (i.e. transactions
722+ - Includes information on slow transactions, which are transactions
753723 that exceed the :setting:`operationProfiling.slowOpThresholdMs`
754724 threshold) under the :data:`TXN` log component.
755725
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