> db.createCollection("ts", {timeseries: {timeField: "t", metaField: "tag"}}); { "ok" : 1 } > db.ts.insert({t: new ISODate(), tag: 1, f: 1}); WriteResult({ "nInserted" : 1 }) > db.ts.createIndex({tag: 1}); { "numIndexesBefore" : 1, "numIndexesAfter" : 2, "createdCollectionAutomatically" : false, "ok" : 1 } > db.ts.getIndexes(); [ { "v" : 2, "key" : { "tag" : 1, "t" : 1 }, "name" : "tag_1_t_1" }, { "v" : 2, "key" : { "tag" : 1 }, "name" : "tag_1" } ] > db.ts.deleteMany({tag: 1, f: 1}); { "acknowledged" : true, "deletedCount" : 0 } > db.ts.dropIndex("tag_1"); { "nIndexesWas" : 2, "ok" : 1 } > db.ts.deleteMany({tag: 1, f: 1}); { "acknowledged" : true, "deletedCount" : 1 }