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DOCS-617 expand slightly the Isolation section in write-operations #375

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Nov 5, 2012
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DOCS-617 expand slightly the Isolation section in write-operations #375

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DOCS-617 expand slightly the Isolation section in write-operations
kay-kim Nov 5, 2012
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DOCS-617 edits
kay-kim Nov 5, 2012
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18 changes: 10 additions & 8 deletions draft/core/write-operations.txt
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Expand Up @@ -284,16 +284,18 @@ and :doc:`/applications/indexes`.
Isolation
---------

All operations inside of a *single* MongoDB document are atomic. An
update operation may modify more than one sub-document within a single
MongoDB document (or record) in a single operation that will either
succeed or fail and cannot leave the document in an in-between state.
When a single write operation modifies multiple documents, the
operation as a whole is not atomic, but the modification of each
document is. The modification of a single Mongo document (or record)
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@tychoish tychoish Nov 5, 2012

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When a single write write operation modifies multiple documents, the operation as a whole is not atomic, and other operations may interleave. The modification of a single document, or record, is always atomic, even if the write operation modifies multiple sub-documents within the single record.

remains atomic even if the write operation modifies more than one
sub-document *within* that document.

No other operations are atomic; however, you can attempt to isolate a
sequence of write operations from other read and write operations to
prevent undesirable interactions. For more information see
:doc:`Isolated write operations </reference/operator/atomic>` and
:doc:`/tutorial/perform-two-phase-commits`.
write operation that affects multiple documents using the :doc:`$atomic
isolation operator </reference/operator/atomic>`.
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@tychoish tychoish Nov 5, 2012

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I think we should avoid using $atomic in this section because it's emphatically not atomic.


To isolate a sequence of write operations from other read and write
operations, see :doc:`/tutorial/perform-two-phase-commits`.

Architecture
------------
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