Some commands in MongoDB

2. Query based on the length of a field (title) in the collection

   Db.collections. Find true " This.title.length < " })// Note that kanji is not a character

4. Refresh the config information for the MONGOs cache

   Db.admincommand ({"flushrouterconfig":1})//  Refresh the cache after modifying configuration in config

6. Using pipelines to import a database from one instance node to another instance

   20001 passwd 20002 passwd -D dstdbname--archive

Some commands in MongoDB