Data Flow:

business system –> log –> flume collectiong, aggregating etc. –> kafka streaming 数据清洗和处理 –> spark streaming 流式计算

MongoDB Concepts:

database / collection / document

1. show dbs
2. use database name, access
3. db local current database name
4. show collections
5. CRUD
6. one to many structure

Elasticsearch vs. Solr

1. open http://localhost:9200
2. check collection http://localhost:9200/_cat/indices
3. check index http://localhost:9200/recommender/_search?pretty
4. 条件查询 curl “localhost:9200/recommender/_search?pretty” -d ‘{“query”: {“bool” : {“must” : {“exists” : {“field”: “tags”}}}}}’

SQL

1. count
2. group by
3. order
4. distinct

Zookeeper

1. jps check all java process
2. start: ./bin/zkServer.sh start

Redis

1. run src/redis-server