mongodb_syntax.md

MongoDB Syntax Quick List

Get All Collection Name Operation

• Way1

db.getCollectionNames()

• Way2

db.getCollectionNames().forEach(function(coll_name) {
  print(coll_name);
  /* or other operation like..
  var coll = db.getCollection(coll_name);
  coll.reIndex();
  */

});

Index

• Batch Drop

db.getCollection('ledger').dropIndexes(['idx_1', 'idx2'])

• Batch Create

db.runCommand(
    {
      createIndexes: "wager",
      indexes: [
        {
          key: { field1: 1, field2: -1},
          name: "idx_1"
        },
        {
          key: { field3: -1, field4: 1},
          name: "idx_2"
        }
      ]
    }
  );

$merge

db.getCollection('ledger').aggregate([
    { $project: { _id: 0 } },
    { $merge: { into: 'ledger-to' } }
]);