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GridFS in MongoDB

GridFS

GridFS is responsible for storing and retrieving files, GridFS store file in single document and divides a file into parts, or chunks and stores each or those chunks as a separates document. By default chunk size limit is 255k. GridFS uses two collections to store files, one collection stores the file chunks and other stores file metadata.   
  
Driver or client can reassemble the chunks as needed when you query a GridFS store for a file. We can execute range queries on files stored during GridFS. We can also access information from arbitrary sections of files, which allows you to “skip” into the middle of a video or audio file.

Note:  GridFS retrieving files that exceed the BSON-document size limit of 16MB.

GridFS Collections

GridFS stores files in two collections:

1.       chunks stores the binary chunks.
2.       files stores the file’s metadata. 

GridFS places the collections in a common bucket by prefixing each with the bucket name. By default, GridFS uses two collections with names prefixed by fs bucket:

1.       fs.files
2.       fs.chunks

Note: We can choose a different bucket name than fs, and create multiple buckets in a single database.

Each document in the chunks collection represents a distinct chunk of a file as represented in the GridFS store. Each chunk is identified by its unique ObjectId stored in its _id field.

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