Fragment data to GridFS

On this page

• files  collection
• chunks  collection

Out of  GridFS  dividing sheet storage, note the following cases:

files  collection

In most cases does not require  files  collection fragmented, this collection is usually very small, only contains some meta information collection nor proper key piece of data it can be evenly distributed in the cluster. If you  need  to  files  be fragments may be used  _id  field associated with the application field of the composite sheet made key.

Not to `` files`` fragmentation means that all meta-information files are stored on a slice, in a production environment,  to be  in stores  files  using a replication set on the slices.

chunks  collection

Using the following command  {  files_id  :  . 1  ,  n-  :  . 1  }  to do is key sheet  chunks  set slice:

db.fs.chunks.createIndex( { files_id : 1 , n : 1 } ) db.runCommand( { shardCollection : "test.fs.chunks" , key : { files_id : 1 , n : 1 } } ) 

Only like this can also be used  file_id  fields fragmentation:

db.runCommand( { shardCollection : "test.fs.chunks" , key : { files_id : 1 } } ) 

important

In GridFS storage of  chunks  collection time slice, only two sheets key to select, `` {files_id: 1, n: 1} `` and  {   files_id  :  . 1  }  .

The default  files_id  is  the ObjectId  ,  the ObjectId  is incremented, and therefore all new data will be written to a separate storage slice, the slice if the write load is too large, consider for a key sheet or  files  use a different set of the  _id  value.