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  1. Documentation
  2. DOCS-5314

WriteConcern: clarify that 'w' and 'j' are orthogonal

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      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.

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            kay.kim@mongodb.com Kay Kim (Inactive)
            andrew.ryder@mongodb.com Andrew Ryder (Inactive)
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              Updated:
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              1 year, 14 weeks, 1 day ago