The document discusses using the MongoDB shell for debugging, testing, and administration tasks. It notes some limitations of using JavaScript in the shell, such as number and date handling. It provides examples of common shell commands like insert, update, remove, loading scripts, running commands, and profiling. Useful shell functions are also demonstrated like printjson and forEach. The document concludes by showing how to print indexes, find the largest document, use cursors, define aliases, and work with DBRefs.

1. Mastering the Shell Raw MongoDB (as you like it)

2. What is the shell?

3. What is it good for? Debugging Testing Administration Scripting Glue Not building apps, probably

4. The Bad: JS Types Numbers Suck (but getting better) 32/64bit signed (int/long) – 1.5.4>NumberLong(“”) Displayed funny Everything is a 64bit fp (double) Dates are a challenge new Date(“1/1/1”) Not Date(“1/1/1”) -> string

5. The Bad: JS is Slow Shell Safe/GLE Loops and updates Data conversions Server It pretty much applies here too Be careful with numbers as well

6. Insert, Save, Update, Remove Demo now  for(i = 0; i <1000; i++) { db.test.insert({x:i, ts: new Date()}) }

7. Command Line --eval it/cursor Printing values Pass in a script

8. Loading Scripts Command line load() – also runs

9. Run Commands db.runCommand({…}) db.runCommand(“getLastError”)

10. Useful Commands getCmdLineOpts ping isMaster reIndex sharding replication

11. Profiling setProfilingLevel(lvl, <ms>) 0: none 1: time-based 2: all Reading from profile collection >db.system.profile.find()

12. Help > help > help admin > help misc > db.help() > db.coll.help()

13. Expose Functions Leave off the () to see the function: > db.getSisterDB function (name) { return this.getMongo().getDB(name);

14. Cool functions printjson -> tojson forEach on array/query/cursor > [{x:1},{y:1}].forEach(function(x){printjson(x)}) { "x" : 1 } { "y" : 1 } Object.bsonsize Object.bsonsize(c.findOne({name:”scott”})) load(file) run(file)

15. Print all Indexes db.getCollectionNames(). forEach(function(x){ print(“Collection: “ + x); printjson(db[x].getIndexes()); })

16. Getting the Biggest Doc var cursor = db.coll.find(); var biggest=0; var doc = {}; cursor.forEach(function (x) { var size = Object.bsonsize(x); if (size > biggest) { biggest=size; doc = x; } });

17. Cursors: it “it” global var find automatically sets it

18. Aliases Show collections/tables

19. DBRef Has fetch() Easy to create

20. Questions That’s all…folks! ScottHernandez@gmail.com