MongoDB: update every document on one field -

i have collected named foo hypothetically.

each instance of foo has field called lastlookedat unix timestamp since epoch. i'd able go through mongodb client , set timestamp existing documents (about 20,000 of them) current timestamp.

what's best way of handling this?

in mongo shell, or mongodb client:

• mongodb >= 3.2:

db.foo.updatemany({}, {$set: {lastlookedat: date.now() / 1000}})

see http://docs.mongodb.org/manual/tutorial/modify-documents/#update-multiple-documents

• {} condition (the empty condition matches document)
• {$set: {lastlookedat: date.now() / 1000}} want do

• mongodb >= 2.2:

db.foo.update({}, {$set: {lastlookedat: date.now() / 1000}}, { multi: true })

see http://docs.mongodb.org/manual/tutorial/modify-documents/#update-multiple-documents

• {} condition (the empty condition matches document)
• {$set: {lastlookedat: date.now() / 1000}} want do
• {multi: true} "update multiple documents" option

• mongodb < 2.2:

db.foo.update({}, {$set: {lastlookedat: date.now() / 1000}}, false, true)

see https://web.archive.org/web/20120613233453/http://www.mongodb.org/display/docs/updating

• {} condition (the empty condition matches document)
• {$set: {lastlookedat: date.now() / 1000}} want do
• false "upsert" parameter (insert if not present, or else update - not want)
• true "multi" parameter (update multiple records)