[DOCS-6561] ReadConcern: Majority undefined with replication PV0 Created: 09/Nov/15 Updated: 24/Feb/16 Resolved: 17/Dec/15 |
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| Status: | Closed |
| Project: | Documentation |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Task | Priority: | Critical - P2 |
| Reporter: | Osmar Olivo | Assignee: | Kay Kim (Inactive) |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Participants: | |||||||||
| Days since reply: | 8 years, 8 weeks, 6 days ago | ||||||||
| Description |
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After some discussion, we've decided to make readConcern: Majority's behavior be undefined when using protocolVersion 0. At some point in the future we will explicitly have readConcern:Majority reads throw errors when using Protocol Version 0, but for now the behaviour is undefined and provides no guarantees. We should recommend always using ProtocolVersion 1 when using readConcerns: Majorioty. Can we make sure this gets reflected in the docs? |
| Comments |
| Comment by Githook User [ 17/Dec/15 ] |
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Author: {u'username': u'kay-kim', u'name': u'kay', u'email': u'kay.kim@10gen.com'}Message: |
| Comment by Andy Schwerin [ 15/Dec/15 ] |
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Let's not change "written" to "made durable" just yet. |
| Comment by Osmar Olivo [ 15/Dec/15 ] |
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Ultimately, it does give an error if you try to use Read Concern Majority with pv0. You will get a NotEnabled error and the message is "Replica sets running protocol version 0 do not support readConcern: majority". This went out with 3.2.0. Let's make sure this get's documented appropriately. Also, the definition for readConcern: Majority is currently "The query will return the node’s most recent copy of the data confirmed as having been written to a majority of the nodes." I think since it's only supported in pv1 it's safe to replace the word "written", with "made durable". |
| Comment by Andy Schwerin [ 20/Nov/15 ] |
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I think |
| Comment by Osmar Olivo [ 19/Nov/15 ] |
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let's slowdown everyone, this decision may have ended up being changed. milkie schwerin I believe we may have decided to support readConcern: Majority on PV0 after all with the changes in If no changes are needed let's close this ticket. Thanks. |
| Comment by A. Jesse Jiryu Davis [ 19/Nov/15 ] |
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Drivers must all throw errors if the user sets a read concern and the server does not support it: Also, let's be careful to distinguish wire protocol version and replication protocol version, I was confused when I first read this. Drivers send readConcern to servers with wire protocol version 4. I believe that a server must, additionally, be using replication protocol version 1 to support readConcernLevel majority. |