1、HIVE Data Warehousing & Analytics on Hadoop,Joydeep Sen Sarma, Ashish Thusoo Facebook Data Team,Why Another Data Warehousing System?,Problem: Data, data and more data 200GB per day in March 2008 back to 1TB compressed per day today The Hadoop Experiment Problem: Map/Reduce is great but every one is
2、not a Map/Reduce expert I know SQL and I am a python and php expert So what do we do: HIVE,What is HIVE?,A system for querying and managing structured data built on top of Map/Reduce and Hadoop We had: Structured logs with rich data types (structs, lists and maps) A user base wanting to access this
3、data in the language of their choice A lot of traditional SQL workloads on this data (filters, joins and aggregations) Other non SQL workloads,Data Warehousing at Facebook Today,Web Servers,Scribe Servers,Filers,Hive on Hadoop Cluster,Oracle RAC,Federated MySQL,HIVE: Components,HDFS,Hive CLI,DDL,Que
4、ries,Browsing,Map Reduce,MetaStore,Thrift API,SerDe,Thrift,Jute,JSON,Execution,Hive QL,Parser,Planner,Mgmt. Web UI,Data Model,Logical Partitioning,HashPartitioning,Schema,Library,clicks,HDFS,MetaStore,/hive/clicks,/hive/clicks/ds=2008-03-25,/hive/clicks/ds=2008-03-25/0,Tables,#Buckets=32 Bucketing I
5、nfo Partitioning Cols,Dealing with Structured Data,Type system Primitive types Recursively build up using Composition/Maps/Lists Generic (De)Serialization Interface (SerDe) To recursively list schema To recursively access fields within a row object Serialization families implement interface Thrift D
6、DL based SerDe Delimited text based SerDe You can write your own SerDe Schema Evolution,MetaStore,Stores Table/Partition properties: Table schema and SerDe library Table Location on HDFS Logical Partitioning keys and types Other information Thrift API Current clients in Php (Web Interface), Python (
7、old CLI), Java (Query Engine and CLI), Perl (Tests) Metadata can be stored as text files or even in a SQL backend,Hive CLI,DDL: create table/drop table/rename table alter table add column Browsing: show tables describe table cat table Loading Data Queries,Hive Query Language,Philosophy SQL like cons
8、tructs + Hadoop StreamingQuery Operators in initial version Projections Equijoins and Cogroups Group by SamplingOutput of these operators can be: passed to Streaming mappers/reducers can be stored in another Hive Table can be output to HDFS files can be output to local files,Hive Query Language,Pack
9、age these capabilities into a more formal SQL like query language in next version Introduce other important constructs: Ability to stream data thru custom mappers/reducers Multi table inserts Multiple group bys SQL like column expressions and some XPath like expressions Etc,Joins,Joins FROM page_vie
10、w pv JOIN user u ON (pv.userid = u.id) INSERT INTO TABLE pv_users SELECT pv.*, u.gender, u.age WHERE pv.date = 2008-03-03;Outer JoinsFROM page_view pv FULL OUTER JOIN user u ON (pv.userid = u.id) INSERT INTO TABLE pv_users SELECT pv.*, u.gender, u.age WHERE pv.date = 2008-03-03;,Aggregations and Mul
11、ti-Table Inserts,FROM pv_users INSERT INTO TABLE pv_gender_uu SELECT pv_users.gender, count(DISTINCT pv_users.userid) GROUP BY(pv_users.gender) INSERT INTO TABLE pv_ip_uu SELECT pv_users.ip, count(DISTINCT pv_users.id) GROUP BY(pv_users.ip);,Running Custom Map/Reduce Scripts,FROM ( FROM pv_users SEL
12、ECT TRANSFORM(pv_users.userid, pv_users.date) USING map_script AS(dt, uid) CLUSTER BY(dt) map INSERT INTO TABLE pv_users_reduced SELECT TRANSFORM(map.dt, map.uid) USING reduce_script AS (date, count);,Inserts into Files, Tables and Local Files,FROM pv_users INSERT INTO TABLE pv_gender_sum SELECT pv_
13、users.gender, count_distinct(pv_users.userid) GROUP BY(pv_users.gender) INSERT INTO DIRECTORY /user/facebook/tmp/pv_age_sum.dir SELECT pv_users.age, count_distinct(pv_users.userid) GROUP BY(pv_users.age) INSERT INTO LOCAL DIRECTORY /home/me/pv_age_sum.dirFIELDS TERMINATED BY , LINES TERMINATED BY 01
14、3 SELECT pv_users.age, count_distinct(pv_users.userid) GROUP BY(pv_users.age);,Hadoop Usage Facebook,Types of Applications: Summarization Eg: Daily/Weekly aggregations of impression/click counts Ad hoc Analysis Eg: how many group admins broken down by state/country Data Mining (Assembling training d
15、ata) Eg: User Engagement as a function of user attributes,Hadoop Usage Facebook,Usage statistics: Total Users: 140 (about 50% of engineering !) in the last 1 months Hive Data (compressed): 80 TB total, 1TB incoming per day Job statistics: 1000 jobs/day 100 loader jobs/day,Hadoop Improvements Faceboo
16、k,Some problems: No Fair Sharing: Big tasks can hog the cluster No snapshots: What if a software bug corrupts the NameNode transaction log Solutions: Simple fair sharing (Matie Zaharia) Investigating Snapshots (Dhrubha Bortharkur),Conclusion,JIRA http:/issues.apache.org/jira/browse/HADOOP-3601 Soon to be checked into hadoop trunk Release available in hadoop version 0.19 People: Suresh Anthony Zheng Shao Prasad Chakka Pete Wyckoff Namit Jain Raghu Murthy Joydeep Sen Sarma Ashish Thusoo,
