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# Merge modes for the document source merge stage.

global:
    cpp_namespace: "mongo"

imports:
    - "mongo/idl/basic_types.idl"

enums:
    MergeWhenMatchedMode:
        description: "Possible merge mode values for $merge's 'whenMatched' field."
        type: string
        values:
            kFail: "fail"
            kKeepExisting: "keepExisting"
            kMerge: "merge"
            # Technically, we don't need this item, as the 'pipeline' value, as a string, is not
            # supported by the 'whenMatched' field. Instead, a pipeline definition, as an array of
            # objects, should be used. However, to avoid special casing logic in
            # DocumentSourceMerge, and to keep all merge strategy definitions in a single
            # descriptors map, which keys are pairs of whenMatched/whenNotMatched values, this
            # 'kPipeline' element is added for internal use only.
            kPipeline: "pipeline"
            kReplace: "replace"

    MergeWhenNotMatchedMode:
        description: "Possible merge mode values for $merge's 'whenNotMatched'. field"
        type: string
        values:
            kDiscard: "discard"
            kFail: "fail"
            kInsert: "insert"