@@ -15,18 +15,18 @@ Transactions
1515 :class: twocols
1616
1717.. meta::
18- :description: For situations that require atomicity of reads and writes to multiple documents (in a single or multiple collections), MongoDB supports multi-document transactions.
18+ :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 .
1919 :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
2020
2121In MongoDB, an operation on a single document is atomic. Because you can
2222use embedded documents and arrays to capture relationships between data
2323in a single document structure instead of normalizing across multiple
2424documents and collections, this single-document atomicity obviates the
25- need for multi-document transactions for many practical use cases.
25+ need for distributed transactions for many practical use cases.
2626
2727For situations that require atomicity of reads and writes to multiple
2828documents (in a single or multiple collections), MongoDB supports
29- multi-document transactions. With distributed transactions,
29+ distributed transactions. With distributed transactions,
3030transactions can be used across multiple operations, collections,
3131databases, documents, and shards.
3232
@@ -279,32 +279,10 @@ upper-right to set the language of the following example.
279279Transactions and Atomicity
280280--------------------------
281281
282- .. note :: Distributed Transactions and Multi-Document Transactions
282+ .. include :: /includes/transactions/distributed-transaction-repl-shard-support.rst
283283
284- Starting in MongoDB 4.2, the two terms are synonymous. Distributed
285- transactions refer to multi-document transactions on sharded
286- clusters and replica sets. Multi-document transactions (whether on
287- sharded clusters or replica sets) are also known as distributed
288- transactions starting in MongoDB 4.2.
289-
290- For situations that require atomicity of reads and writes to multiple
291- documents (in a single or multiple collections), MongoDB supports
292- multi-document transactions:
293-
294- - **In version 4.0**, MongoDB supports multi-document transactions on
295- replica sets.
296-
297- - **In version 4.2**, MongoDB introduces distributed transactions,
298- which adds support for multi-document transactions on sharded
299- clusters and incorporates the existing support for
300- multi-document transactions on replica sets.
301-
302- To use transactions on MongoDB 4.2 deployments (replica sets and
303- sharded clusters), clients :red:`must` use MongoDB drivers updated for
304- MongoDB 4.2.
305-
306- Multi-document transactions are atomic (i.e. provide an
307- "all-or-nothing" proposition):
284+ Distributed transactions are atomic. They provide an "all-or-nothing"
285+ proposition:
308286
309287- When a transaction commits, all data changes made in the transaction
310288 are saved and visible outside the transaction. That is, a transaction
@@ -330,7 +308,7 @@ Transactions and Operations
330308---------------------------
331309
332310Distributed transactions can be used across multiple operations,
333- collections, databases, documents, and, starting in MongoDB 4.2, shards.
311+ collections, databases, documents, and shards.
334312
335313For transactions:
336314
@@ -350,19 +328,15 @@ For a list of operations not supported in transactions, see
350328Create Collections and Indexes In a Transaction
351329~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
352330
353- Starting in MongoDB 4.4, you can perform the following operations inside
354- of a :ref:`multi-document transaction <transactions>` as long as
355- the transaction is not a cross-shard write transaction:
331+ You can perform the following operations inside of a :ref:`distributed
332+ transaction <transactions>` as long as the transaction is not a
333+ cross-shard write transaction:
356334
357335- Create collections.
358336
359337- Create indexes on new empty collections created earlier in the same
360338 transaction.
361339
362- In MongoDB 4.2 and earlier, operations that affect the database catalog,
363- such as creating or dropping a collection or an index, are
364- :red:`disallowed` in transactions.
365-
366340When creating a collection inside a transaction:
367341
368342- You can :ref:`implicitly create a collection
@@ -461,8 +435,7 @@ Restricted Operations
461435Transactions and Sessions
462436-------------------------
463437
464- - Transactions are associated with a session; i.e. you start a
465- transaction for a session.
438+ - Transactions are associated with a session
466439
467440- At any given time, you can have at most one open transaction for a
468441 session.
@@ -540,20 +513,17 @@ Transactions support the following read concern levels:
540513``"majority"``
541514``````````````
542515
543- - Read concern :readconcern:`"majority"` returns data that has been
544- acknowledged by a majority of the replica set members (i.e. data
545- cannot be rolled back) **if** the transaction commits with
546- :ref:`write concern "majority" <transactions-write-concern>`.
547-
548- - If the transaction does not use :ref:`write concern "majority"
549- <transactions-write-concern>` for the commit, the
550- :readconcern:`"majority"` read concern provides **no** guarantees that
551- read operations read majority-committed data.
516+ - If the transaction commits with :ref:`write concern "majority"
517+ <transactions-write-concern>`, read concern :readconcern:`"majority"`
518+ returns data that has been acknowledged by a majority of the replica
519+ set members and can't be rolled back. Otherwise, read concern
520+ :readconcern:`"majority"` provides no guarantees that read operations
521+ read majority-committed data.
552522
553- - For transactions on sharded cluster, :readconcern:`"majority"` read
554- concern cannot guarantee that the data is from the same snapshot
555- view across the shards. If snapshot isolation is required, use
556- :ref:`transactions-read-concern-snapshot` read concern .
523+ - For transactions on sharded cluster, read concern
524+ :readconcern:`"majority"` can't guarantee that the data is from the
525+ same snapshot view across the shards. If snapshot isolation is
526+ required, use read concern :ref:`transactions-read-concern-snapshot`.
557527
558528.. _transactions-read-concern-snapshot:
559529
@@ -607,7 +577,7 @@ You can set the transaction-level :doc:`write concern
607577 <replica-set-arbiter-configuration>`. See
608578 :ref:`wc-default-behavior`.
609579
610- - :writeconcern:`w: 1 <\<number\>>` in MongoDB 4.4 and earlier.
580+ - :writeconcern:`w: 1 <\<number\>>`
611581
612582.. seealso::
613583
@@ -643,7 +613,7 @@ values, including:
643613
644614- Write concern :writeconcern:`w: "majority" <"majority">` returns
645615 acknowledgement after the commit has been applied to a majority
646- (M) of voting members; i.e. the commit has been applied to the
616+ (M) of voting members, meaning the commit has been applied to the
647617 primary and (M-1) voting secondaries.
648618
649619- When you commit with :writeconcern:`w: "majority" <"majority">`
@@ -740,7 +710,7 @@ MongoDB provides various transactions metrics:
740710
741711 * - :binary:`~bin.mongod` and :binary:`~bin.mongos` log messages
742712
743- - Includes information on slow transactions (i.e. transactions
713+ - Includes information on slow transactions, which are transactions
744714 that exceed the :setting:`operationProfiling.slowOpThresholdMs`
745715 threshold) under the :data:`TXN` log component.
746716
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