MongoSF - mongodb @ foursquare

mongodb @ foursquareMongoSF - 5/24/2011Jorge Ortiz (@jorgeortiz85)

what is foursquare?location-based social network - “check-in” to bars,restaurants, museums, parks, etc friend-finder (where are my friends right now?) virtual game (badges, points, mayorships) city guide (local, personalized recommendations) location diary + stats engine (where was I a year ago?) specials (get rewards at your favorite restaurant)

foursquare: the numbers>9M users~3M checkins/day>15M venues>300k merchants>60 employees

foursquare: the tech Nginx, HAProxy Scala, Lift MongoDB, PostgreSQL (legacy) (Kestrel, Munin, Ganglia, Python, Memcache, ...) All on EC2

foursquare <3’s mongodbfastindexes & rich queriessharding, auto-balancingreplication (see: http://engineering.foursquare.com/)geo-indexesamazing support

mongodb: our numbers8 clusters some sharded, some not some master/slave, some replica set~40 machines (68.4GB, m2.4xl on EC2)2.3 billion records~15k QPS

mongodb: lessons learnedkeep working set in memoryavoid long-running queries (reads or writes)monitor everything (especially per-collection stats)shard from day 1beware EBSuse small field names for large collections

keep working set in memory

avoid long-running queries

monitor everything(per collection stats)

shard from day 1

beware EBS

use small field names forlarge collections

mongodb: pain pointsmongos -- failover and thundering herdsindex creation -- production impact unclearauto-balancing -- getting therereplication chains -- use replica sets

rogue: a scala dsl for mongo type-safe all mongo query features logging & validation hooks pagination index-aware http://github.com/foursquare/rogue

mongo-java-driver queryval query = (BasicDBOBjectBuilder .start .push(“mayorid”) .add(“$lte”, 100) .pop .push(“veneuname”) .add(“$eq”, “Starbucks”) .pop .get)

rogue: code exampleVenue where (_.mayorid <= 100) and (_.venuename eqs “Starbucks”) and (_.tags contains “wifi”) and (_.latlng near (39.0, -74.0, Degrees(0.2)) orderDesc (_._id) fetch (5)

rogue: schema exampleclass Venue extends MongoRecord[Venue] { object _id extends ObjectIdField(this) object venuename extends StringField(this) object mayorid extends LongField(this) object tags extends ListField[String](this) object latlng extends LatLngField(this)}

rogue: logging & validation logging: slf4j Tracer validation: radius, $in size index checks

rogue: paginationval query: Query[Venue] = ...val vs: List[Venue] = (query .countPerPage(20) .setPage(5) .fetch())

rogue: cursorsval query: Query[Checkin] = ...for (checkin <- query) { ... f(checkin) ...}

rogue: index-awareval vs: List[Checkin] = (Checkin where (_.userid eqs 646) and (_.venueid eqs vid) fetch ())

rogue: index-awareval vs: List[Checkin] = (Checkin where (_.userid eqs 646) and (_.venueid eqs vid) // hidden scan! fetch ())

rogue: index-awareval vs: List[Checkin] = (Checkin where (_.userid eqs 646) // known index scan (_.venueid eqs vid) // known scan fetch ())

rogue: future directions iteratees for cursors compile-time index checking select partial objects generate full javascript for mapreduce

we’re hiring (nyc & sf)http://foursquare.com/jobs jorge@foursquare.com @jorgeortiz85

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MongoSF - mongodb @ foursquare

by jorgeortiz85 on May 25, 2011

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