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Change the Size of a Capped Collection
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New in version 6.0.
To change the size of a capped collection, use the collMod command's
cappedSize option. cappedSize is specified in bytes, and must be
greater than 0 and less than or equal to 1024^5 (1 PB).
If cappedSize is less than the current size of the collection,
MongoDB removes the excess documents on the next insert operation.
About this Task
Generally, TTL (Time To Live) indexes offer better performance and more flexibility than capped collections. TTL indexes expire and remove data from normal collections based on the value of a date-typed field and a TTL value for the index.
Capped collections serialize inserts and therefore have worse concurrent insert performance than non-capped collections. Before you create a capped collection, consider if you can use a TTL index instead.
Before you Begin
Create a capped collection called log that has a maximum size of
2,621,440 bytes:
db.createCollection( "log", { capped: true, size: 2621440 } )
Steps
Run the following command to set the maximum size of the log
collection to 5,242,880 bytes:
db.runCommand( { collMod: "log", cappedSize: 5242880 } )