New in version 6.0.
To change the maximum number of documents in a capped collection, use the collMod command's
cappedMax option.
If
cappedMaxis less than or equal to0, there is no maximum document limit.If
cappedMaxis less than the current number of documents in 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 write operations and therefore have worse concurrent insert, update, and delete 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 can store a maximum of
20,000 documents:
db.createCollection( "log", { capped: true, size: 5242880, max: 20000 } )Steps
Run the following command to set the maximum number of documents in the
log collection to 5,000:
db.runCommand( { collMod: "log", cappedMax: 5000 } )