[SERVER-22624] Why the journal is unnecessary for WiredTiger Created: 16/Feb/16 Updated: 17/Feb/16 Resolved: 17/Feb/16 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | WiredTiger |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Question | Priority: | Trivial - P5 |
| Reporter: | Nilap Shah | Assignee: | Unassigned |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
MongoDB 3.0 |
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| Participants: |
| Description |
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I just want to know |
| Comments |
| Comment by Ramon Fernandez Marina [ 17/Feb/16 ] |
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nilap.shah@gmail.com, please note that the SERVER project is for reporting bugs or feature suggestions for the MongoDB server. For MongoDB-related support discussion please post on the mongodb-user group or Stack Overflow with the mongodb tag, where your question will reach a larger audience. A question like this involving more discussion would be best posted on the mongodb-user group. See also our Technical Support page for additional support resources. Regards, |
| Comment by Alexander Gorrod [ 16/Feb/16 ] |
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WiredTiger uses a protocol called MVCC, which means that we never overwrite data on disk. This allowed us to implement a mechanism called checkpointing that saves the state of a database at a particular point in time. Those checkpoints provide consistent durability guarantees similar to journaling. The difference between checkpointing and journaling is that it is much more expensive to create a checkpoint than it is to journal an operation. Which means checkpointing isn't a practical solution for applications that need to guarantee that updates are durable (i.e: available after a crash) soon after they are submitted. |