[Drivers] ACID transaction description #143
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jeff-allen-mongo
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jeff-allen-mongo
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@rachel-mack thanks for this update! Left a few minor comments.
drivers/acid-transactions.rst
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| ACID transactions using sessions. These transactions use the snapshot isolation | ||
| level so applications see a consistent set of data while the transaction is |
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This is a nit, but a small suggestion to possibly better explain what we mean by "snapshot isolation".
| ACID transactions using sessions. These transactions use the snapshot isolation | |
| level so applications see a consistent set of data while the transaction is | |
| ACID transactions using sessions. Sessions operate on data from a single point-in-time snapshot, so applications see a consistent set of data while the transaction is |
drivers/acid-transactions.rst
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| operations on multiple documents or collections, MongoDB supports multi-document | ||
| ACID transactions using sessions. These transactions use the snapshot isolation | ||
| level so applications see a consistent set of data while the transaction is | ||
| running and write concerns to ensure changes are safely saved. With these |
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Re "write concerns to ensure changes are safely saved.", I'm not totally sure I understand what this means. Maybe something like:
"changes to data are committed safely" ?
drivers/acid-transactions.rst
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| level so applications see a consistent set of data while the transaction is | ||
| running and write concerns to ensure changes are safely saved. With these | ||
| features, MongoDB provides ACID guarantees that are comparable to those found in | ||
| traditional relational databases. No newline at end of file |
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How important is this last sentence? I'm a little concerned that it could potentially read like we are "comparable", but maybe not as a good. But if this is a requirement from product or similar, I'm fine leaving.
colbying
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colbying
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what context are these documentation changes? could you link me to a staging URL so I can understand the context?
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| By default, operations on single documents conform to ACID standards. For | ||
| operations on multiple documents or collections, MongoDB supports multi-document | ||
| ACID transactions by using sessions. Sessions operate on data from a single |
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using sessions alone won't guarantee that your mutli-document writes will happen atomically, you need to create a transaction within that session.
| transactions are required in some industries where errors or partial updates | ||
| could lead to serious financial, legal, or safety consequences. | ||
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| By default, operations on single documents conform to ACID standards. For |
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who is the intended reader here? for readers who are technical, "conform to ACID standards" may be a bit too vague of a statement here.
Consistency - MongoDB offers causal consistency using sessions
Isolation - Any insert/update/delete of a single document is atomic and fully isolated; other clients never see a partial update to a document. MongoDB’s multi-document transaction protocol is designed to provide snapshot isolation: a transaction reads from a stable snapshot taken at (or just before) the transaction start, and other clients cannot see its in-progress writes.
Durability - as long as you have write concern: majority, your writes are durable though node failures.
It depends on how technical the reader is, but I would er on the side of including some of the nuance above.
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This snippet will be applies to all driver's docs sets, along with instructions to update the existing transaction example to ensure that:
majorityat the client level