When does node-mongodb-native hits the database? -

When does node-mongodb-native hits the database? -

i have problem understanding when database nail when using node-mongodb-native. couldn't find reference on that. callback based, gave me feeling every single phone call hits database ... example, 2 snippets different in terms of how many times database nail :

// ---- 1 db.collection('bla', function(err, coll) { coll.findone({'blo': 'bli'}, function(err, doc) { coll.count(function(err, count) { console.log(doc, count) }) }) }) // ---- 2 db.collection('bla', function(err, coll) { coll.findone({'blo': 'bli'}, function(err, doc) { db.collection('bla', function(err, coll) { coll.count(function(err, count) { console.log(doc, count) }) }) }) })

i wondering whether can cache instances of collections , cursors. example, why not fetch collections need once, @ server start, , reuse same instances indefinitely ?

i'd understand how whole thing work, i'd appreciate link explaining stuff in details.

looking @ source code node.js driver collection seems not ping mongodb upon creation of collection unless have strict mode on: https://github.com/mongodb/node-mongodb-native/blob/master/readme.md#strict-mode

the source code looked @ ( https://github.com/mongodb/node-mongodb-native/blob/master/lib/mongodb/db.js#l446 ) reinforced thought if strict not on seek , create new node.js collection object , run callback.

however findone , count break "lazy" querying of node.js , forcefulness query database in order results.

note: count beingness on collection won't enforce "true" count of items in collection. instead garnish info collection meta.

so first snippet should see 2 queries run. 1 findone , 1 count , 2 sec snippet since creating collection after findone should not enforce query mongodb.

mongodb node-mongodb-native