Details
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Task
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Resolution: Won't Fix
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Major - P3
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Description
RE: http://docs.mongodb.org/manual/core/write-concern/
The above page may induce confusion due to the mixed use of w and j options to produce overall effects. I think the different levels would be OK but we should clarify that w and j are having different effects and do not directly collude.
This page does a better job of making this distinction clearer: http://docs.mongodb.org/manual/reference/write-concern/
Perhaps direct links to this page from the first one, regarding the individual options may be enough.
w is effectively a "network level" setting, specifying how commands can be acknowledged by members within a set (1, default, meaning only the one you are connected to).
j is effectively a "local" setting, specifying how commands must be durably written to the instance one is connected to but has no impact on the write-concern except in the case where w:0 is zero (j overrides w).
In combination, this means that w set to "majority" and j set to true is meaningful. Though the linked page gives the impression that perhaps it isn't.
w and j are orthogonal.