ruby - Is mongoid automatically indexing the field _id? -


i on first experience nosql databases, using mongodb. using ruby-2.2.2 rails-3.2.22 , mongoid-3.17

i've seen mongoid automatically includes _id field in models.

but,

do need manually create index field or automatically created happens activerecord in relational databases?

how can see list of indexes exists each model?

to list of existing indexes should ask inside mongodb console (mongo binary on localhost):

use databasename; db.collectionname.getindexes();

where databasename database name , collectionname collection name accordingly. http://docs.mongodb.org/manual/reference/method/db.collection.getindexes/

and yes, mongodb has indexes _id fields automatically. http://docs.mongodb.org/manual/core/index-single/#single-field-indexes


Comments

Post a Comment

Popular posts from this blog

How to connect android app to App engine -

i'm trying connect app in android server i've opened on appengine. my server's name : dddd-daniel-2345 , website server : http://dddd-daniel-2345.appspot.com/ this how connect android app server in app engine: app.yaml: application: dddd-daniel-2345 version: 1 runtime: python27 api_version: 1 threadsafe: yes handlers: - url: .* script: main.app libraries: - name: webapp2 version: "2.5.2" main.py: #!/usr/bin/env python # # copyright 2007 google inc. google.appengine.api import users import webapp2 class userhandler(webapp2.requesthandler): def get(self): user = users.get_current_user() if user: greeting = ('%s,%s,%s' % (user.email(),user.user_id(),user.nickname())) else: greeting = ('not logged in') self.response.out.write(greeting) app = webapp2.wsgiapplication([('/', userhandler),], debug=true) my applications code : add manifast main....
Read more

gcc - MinGW's ld cannot perform PE operations on non PE output file -

i know there other similar questions out there, stackoverflow or not. i've researched lot this, , still didn't find single solution. i'm doing operative system side project. i've been doing in assembly, wanna join c code. test, made assembly code file (called test.asm): [bits 32] global _a section .text _a: jmp $ then made c file (called main.c): extern void a(void); int main(void) { a(); } to link, used file (called make.bat): "c:\mingw\bin\gcc.exe" -ffreestanding -c -o c.o main.c nasm -f coff -o asm.o test.asm "c:\mingw\bin\ld.exe" -ttext 0x100000 --oformat binary -o out.bin c.o asm.o pause i've been researching ages, , i'm still struggling find answer. hope won't flagged duplicate. acknowledge existence of similar questions, have different answers, , none work me. question: what doing wrong? old mingw versions had problem "ld" not able create non-pe files @ all. maybe current versions...
Read more

php - display validation error message next to the textbox in codeigniter -

Image
i'm newbie codeigniter.i want display error message next text box.my view file create.php contains following code. <?php echo validation_errors(); //validation echo form_open('news/create'); //create form ?> <div class="boxes"> <div class="common"> <div class="lables"> <label for="name">name</label> </div> <div class="text_boxes"> <input type="text" name="uname" /><div id="infomessage"><?php echo $message;?></br> </div> </div>` and below controller model: public function create() { $this->load->helper('form'); $this->load->library('form_validation'); $data['title'] = 'insert items'; $this->form_validation->set_rules('uname','required|min_length[6]|m...
Read more