Many chunks of a collection relative to other shards. MongoDB migrates chunks when a shard contains too They grow beyond the configured chunk size, which by default isġ28 megabytes. Chunk ranges are inclusive of the lower boundaryĪnd exclusive of the upper boundary. chunk A contiguous range of shard key values within a particular The md5 algorithm is sometimes used as a checksum. checksum A calculated value used to ensure data integrity. cartesian product The result of combining two data sets such that the combined setĬontains every possible combination of values. cardinality The measure of the number of elements within a set of values.įor example, the set A = contains 3 elements,Īnd has a cardinality of 3. The MongoDB oplog that is used in replication is aĬapped collection. Overwrites its oldest entries when it reaches its maximum size. capped collection A fixed-sized collection that automatically System can provide any two of these features, but never all CAP Theorem Given three properties of computing systems, consistency,Īvailability, and partition tolerance, a distributed computing For a list of BSON types, see BSON Types. BSON types The set of types supported by the BSON serializationįormat. Of JSON (JavaScript Object Notation) documents. BSON A serialization format used to store documents and make ForĮxample, if a range of date field values is outside of a specifiedĭate range, the documents in that range are eliminated from the bounded collection scan A plan used by the query optimizer thatĮliminates documents with specific field value ranges. See Sort and Index Use for more information on blocking sort SeeĪ sort that must be performed in memory before output is returned.īlocking sorts may impact performance for large data sets. Maintenance operations on a sharded cluster. Administrators must disable the balancer for all Sharded cluster and manages the migration of chunks. balancer An internal MongoDB process that runs in the context of a backup cursor A tailable cursor that points to a list of backup files.īackup cursors are for internal use only. B-tree A data structure commonly used by database management systems to authorization Provisioning of access to databases and operations. authentication Verification of the user identity. Involve writes to multiple documents, all writes to each document must atomic operation An atomic operation is a write operation which either completesĮntirely, or does not complete at all. arbiter A member of a replica set that exists solely to vote inĮlections. aggregation pipeline The set of MongoDB operators that let you calculate aggregate For more information, seeĪggregation Operations. aggregation Any of a variety of operations that reduces and summarizes largeĮxamples of aggregation operations. Must have access to the admin database to run certainĪdministrative commands. action An operation the user can perform on a resource. For a list of accumulator operations, see Maintains state between documents in the aggregation accumulator An expression in an aggregation pipeline that If you create a new document without an _id field, MongoDBĪutomatically creates the field and assigns a uniqueīSON ObjectId. Think of the _id field as the document's primary key. _id A field required in every MongoDB document. To use database commands, see Issue Commands. There’s really no need to look elsewhere.$cmd A special virtual collection that exposes MongoDB's If you’re searching for a boating/sailing navigation app like I was, give this one a try. I happily deleted all of the other marine apps on the iPad. The only other marine app I use (and don’t really need) now is PredictWind, just to get really granular on wind speed and direction. and it’s completely FREE! If you choose to upgrade (for just $19/year) you can even see more detailed weather forecasts and AIS traffic on-screen.Īs a tech CMO and recreational sailor I have to tell you, CMAP has every single thing I was looking for and nothing that I wasn’t - some serious thought went into C-MAP, from its design and feature set to its user experience. You get intuitive options for distance/time estimating, mapping out routes, basic weather/wave/tide data, your GPS coordinates, even points of interest in the area. C-MAP was the hands-down winner so I felt compelled to write a review and let people know how great CMAP is.įirst of all C-MAP stands in stark contrast to competing marine navigation maps because it’s uncluttered and the maps are super snappy and run butter-smooth on my iPad Air. I spent considerable time this past week trying out C-MAP and other marine navigation apps like iNavX, Navionics, Wavve, etc., in an effort to find the best one to run on my iPad while sailing.
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