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#
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# ShardCollectionType type
#
# This type represents the layout and contents of documents contained in the shard server's
# config.cache.collections collection. All manipulation of documents coming from that collection
# should be done with this class.
#
# Expected shard server config.cache.collections collection format:
#   {
#      "_id" : "foo.bar",
#      "uuid" : UUID,                                   // optional in 3.6
#      "epoch" : ObjectId("58b6fd76132358839e409e47"),  // will remove when UUID becomes available
#      "key" : {
#          "_id" : 1
#      },
#      "defaultCollation" : {
#          "locale" : "fr_CA"
#      },
#      "unique" : false,
#      "refreshing" : true,                                 // optional
#      "lastRefreshedCollectionVersion" : Timestamp(1, 0),  // optional
#      "enterCriticalSectionCounter" : 4                    // optional
#      "reshardingFields": {                                // optional
#          "uuid" : UUID,
#          "state" : CoordinatorState<kInitialized>,
#          // Only populated if the coordinator has encountered an error.
#          "abortReason": BSONObj   
#          // Only populated if this collection is the original sharded collection.
#          "donorFields" : {
#              "reshardingKey" : {
#                  "_notTheID" : 1
#              }
#          },
#          // Only populated if:
#          // a) This collection is the temporary resharding collection, or
#          // b) This is the original collection and the coordinator has
#          //    chosen to commit
#          "recipientFields" : {
#              "fetchTimestamp" : Timestamp(3, 4),
#              "originalNamespace" : "foo.bar",
#          }
#       }
#   }
#

global:
    cpp_namespace: "mongo"

imports:
    - "mongo/db/basic_types.idl"
    - "mongo/db/keypattern.idl"
    - "mongo/s/chunk_version.idl"
    - "mongo/s/resharding/type_collection_fields.idl"
    - "mongo/s/type_collection_common_types.idl"

structs:
    ShardCollectionTypeBase:
        description: "Represents the layout and contents of documents contained in the shard 
                      server's config.cache.collections collection."
        strict: false
        fields:
            _id:
                cpp_name: nss
                type: namespacestring
                description: "The full namespace (with the database prefix)."
                optional: false
            uuid:
                type: uuid
                description: "The UUID that will be used to create the local collection on each of
                              the shards which have chunks."
                optional: false
            key:
                cpp_name: keyPattern
                type: KeyPattern
                description: "Sharding key. If collection is dropped, this is no longer required."
                optional: false
            defaultCollation:
                type: object_owned
                description: "Optional collection default collation. If missing or set to the empty
                              BSON, implies simple collation."
                default: BSONObj()
            unique:
                type: bool
                description: "Uniqueness of the sharding key."
                optional: false
            reshardingFields:
                description: "Resharding-related fields. Only set when this collection is either the
                              original collection undergoing a resharding operation or this
                              collection is the temporary resharding collection."
                type: TypeCollectionReshardingFields
                optional: true
            allowMigrations:
                cpp_name: pre50CompatibleAllowMigrations
                type: bool
                description: "Whether this collection allows chunks to move. It is required by
                              almost all DDL operations in order to guarantee that the set of
                              shards, which comprise a collection will not change.

                              If the flag is not present it defaults to true.

                              It must be optional and not present when running in FCV 4.4, because
                              binaries prior to 5.0 use strict parsing and will fail."
                optional: true
            timeseriesFields:
                type: TypeCollectionTimeseriesFields
                description: "Time-series collection fields. Only set when this is a time-series
                              buckets collection."
                optional: true

            # What follows below are fields which control DDL operations on the collection object

            enterCriticalSectionCounter:
                type: int
                description: "Currently just an OpObserver signal, thus otherwise ignored."
                optional: true
            refreshing:
                type: bool
                description: "Set by primaries and used by shard secondaries to safely refresh chunk
                              metadata. Indicates whether the chunks collection is current being
                              updated, which means read results won't provide a complete view of the
                              chunk metadata."
                optional: true
            epoch:
                type: objectid
                description: "Uniquely identifies this instance of the collection, in case of
                              drop/create or shard key refine."
                optional: false
            timestamp:
                type: timestamp
                description: "Uniquely identifies this incarnation of the collection. Only changes
                              in case of drop and create, or shard key refine.
                              This field will store the ClusterTime of the Config Server when the
                              collection was created or it's shard key last refined. Because
                              timestamps are comparable, we are able to define a total order in time
                              in the collection. This field will replace Epoch, which are not
                              comparable."
            lastRefreshedCollectionVersion:
                type: timestamp
                cpp_name: lastRefreshedCollectionMajorMinorVersion
                description: "Set by primaries and used by shard secondaries to safely refresh chunk
                              metadata. Indicates the collection version of the last complete chunk
                              metadata refresh, and is used to indicate if a refresh occurred if the
                              value is different than when the caller last checked -- because
                              'refreshing' will be false both before and after a refresh occurs."
                optional: true
            unsplittable:
                type: optionalBool
                description: "Flag that identifies whether the collection is splittable in multiple 
                            chunks. If unsplittable, the collection is always equivalent to a 1 
                            chunk collection."
