Skip to content
This repository was archived by the owner on May 1, 2025. It is now read-only.

DOCSP-47219 Midsync Reads FAQ #612

Merged
merged 4 commits into from
Feb 13, 2025
Merged

DOCSP-47219 Midsync Reads FAQ #612

Changes from 3 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
6c93032
DOCSP-47219-midsync-reads
ajhuh-mdb Feb 12, 2025
27f2916
active voice
ajhuh-mdb Feb 12, 2025
8b21f19
internal feedback
ajhuh-mdb Feb 13, 2025
233015c
MVK feedback
ajhuh-mdb Feb 13, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
33 changes: 19 additions & 14 deletions source/faq.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -26,20 +26,25 @@ following the steps in :ref:`c2c-reconfigure-mid-migration`.
Can I perform reads or writes to my destination cluster while ``mongosync`` is syncing?
---------------------------------------------------------------------------------------

You can perform reads at any time during synchronization.
However, ``mongosync`` combines and reorders writes from the source to destination during synchronization,
and also temporarily modifies various collection characteristics.
As a result, the destination is not guaranteed to match the source at any point in time when the sync is running.
For consistent reads, wait for the migration to :ref:`c2c-api-commit`. To learn more, see :ref:`mongosync-considerations`.

Performing writes to your destination cluster during synchronization results in undefined behavior.
``mongosync`` blocks writes on the destination cluster by default. To learn
more about write-blocking, see :ref:`c2c-write-blocking` and :ref:`c2c-api-start`.

Upon commit, it is only safe to write to the destination cluster when ``canWrite`` is ``true``.
To check the value of ``canWrite``, run the :ref:`c2c-api-progress` endpoint.

To learn more about permissable reads and writes during synchronization, see :ref:`c2c-reads-and-writes`.
``mongosync`` combines and reorders writes from the source to destination during
synchronization, and temporarily modifies collection characteristics. As a
Copy link

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

"combines and reorders writes" -> link to https://www.mongodb.com/docs/cluster-to-cluster-sync/current/reference/mongosync/mongosync-behavior/#consistency
"temporarily modifies" -> link to https://www.mongodb.com/docs/cluster-to-cluster-sync/current/reference/mongosync/mongosync-behavior/#temporary-changes-to-collection-characteristics

Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

updated!

result, ``mongosync`` can't guarantee that the destination matches the source,
including a stale version of the source, at any point in time when the sync is
running. To safely accept traffic to the destination cluster, wait for the
Copy link

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

"running" -> "running, even if the sync is paused"

Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

updated

migration to :ref:`c2c-api-commit`. To learn more, see
:ref:`mongosync-considerations`.

Performing writes to your destination cluster during synchronization results in
undefined behavior. ``mongosync`` blocks writes on the destination cluster by
default. To learn more about write-blocking, see :ref:`c2c-write-blocking` and
:ref:`c2c-api-start`.

Upon commit, it is only safe to write to the destination cluster when
``canWrite`` is ``true``. To check the value of ``canWrite``, run the
:ref:`c2c-api-progress` endpoint.

To learn more about permissable reads and writes during synchronization, see
:ref:`c2c-reads-and-writes`.

.. note::

Expand Down