Introduction to Hive
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Transcript Introduction to Hive
Introduction to Hive
Liyin Tang
[email protected]
Outline
Motivation
Overview
Data Model / Metadata
Architecture
Performance
Cons and Pros
Application
Related Work
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Motivation
Realtime
Hadoop
Cluster
Web Servers
Oracle RAC
Scribe MidTier
Hadoop Hive Warehouse
Scribe Writers
MySQL
http://hadoopblog.blogspot.com/2009/06/hdfs-scribe-integration.html
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Motivation
Limitation of MR
Have to use M/R model
Not Reusable
Error prone
For complex jobs:
Multiple stage of Map/Reduce functions
Just like ask dev to write specify physical
execution plan in the database
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Overview
Intuitive
Make the unstructured data looks like tables
regardless how it really lay out
SQL based query can be directly against these tables
Generate specify execution plan for this query
What’s Hive
A data warehousing system to store structured data on
Hadoop file system
Provide an easy query these data by execution Hadoop
MapReduce plans
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Data Model
Tables
Basic type columns (int, float, boolean)
Complex type: List / Map ( associate array)
Partitions
Buckets
CREATE TABLE sales( id INT, items
ARRAY<STRUCT<id:INT,name:STRING>
) PARITIONED BY (ds STRING)
CLUSTERED BY (id) INTO 32 BUCKETS;
SELECT id FROM sales TABLESAMPLE (BUCKET 1 OUT OF 32)
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Metadata
Database namespace
Table definitions
schema info, physical location In HDFS
Partition data
ORM Framework
All the metadata can be stored in Derby by default
Any database with JDBC can be configed
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Architecture
Map Reduce
Web UI + Hive CLI +
JDBC/ODBC
User-defined
Map-reduce Scripts
HDFS
Browse, Query, DDL
Hive QL
MetaStore
UDF/UDAF
substr
sum
average
Parser
Planner
Execution
Thrift API
Optimizer
SerDe
CSV
Thrift
Regex
FileFormats
TextFile
SequenceFile
RCFile
http://www.slideshare.net/cloudera/hw09-hadoop-development-atfacebook-hive-and-hdfs
8
Performance
GROUP BY operation
Efficient execution plans based on:
Data skew:
how evenly distributed data across a number of
physical nodes
bottleneck VS load balance
Partial aggregation:
Group the data with the same group by value as
soon as possible
In memory hash-table for mapper
Earlier than combiner
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Performance
JOIN operation
Traditional Map-Reduce Join
Early Map-side Join
very efficient for joining a small table with a large
table
Keep smaller table data in memory first
Join with a chunk of larger table data each time
Space complexity for time complexity
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Performance
Ser/De
Describe how to load the data from the file into a
representation that make it looks like a table;
Lazy load
Create the field object when necessary
Reduce the overhead to create unnecessary objects in
Hive
Java is expensive to create objects
Increase performance
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Hive – Performance
Date
SVN Revision
Major Changes
Query A
Query B
Query C
2/22/2009
746906
Before Lazy Deserialization
83 sec
98 sec
183 sec
2/23/2009
747293
Lazy Deserialization
40 sec
66 sec
185 sec
3/6/2009
751166
Map-side Aggregation
22 sec
67 sec
182 sec
4/29/2009
770074
Object Reuse
21 sec
49 sec
130 sec
6/3/2009
781633
Map-side Join *
21 sec
48 sec
132 sec
8/5/2009
801497
Lazy Binary Format *
21 sec
48 sec
132 sec
QueryA: SELECT count(1) FROM t;
QueryB: SELECT concat(concat(concat(a,b),c),d) FROM t;
QueryC: SELECT * FROM t;
map-side time only (incl. GzipCodec for comp/decompression)
* These two features need to be tested with other queries.
http://www.slideshare.net/cloudera/hw09-hadoop-development-atfacebook-hive-and-hdfs
Pros
Pros
A easy way to process large scale data
Support SQL-based queries
Provide more user defined interfaces to
extend
Programmability
Efficient execution plans for performance
Interoperability with other database tools
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Cons
Cons
No easy way to append data
Files in HDFS are immutable
Future work
Views / Variables
More operator
In/Exists semantic
More future work in the mail list
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Application
Log processing
Daily Report
User Activity Measurement
Data/Text mining
Machine learning (Training Data)
Business intelligence
Advertising Delivery
Spam Detection
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Related Work
Parallel databases: Gamma, Bubba, Volcano
Google: Sawzall
Yahoo: Pig
IBM: JAQL
Microsoft: DradLINQ , SCOPE
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Reference
[1] A.Thusoo et al. Hive: a warehousing solution over a
map-reduce framework. Proceedings of VLDB09', 2009.
[2] Hadoop 2009:
http://www.slideshare.net/cloudera/hw09-hadoopdevelopment-at-facebook-hive-and-hdfs
[4] Facebook Data Team:
http://www.slideshare.net/zshao/hive-datawarehousing-analytics-on-hadoop-presentation
[3] Cloudera:
http://www.cloudera.com/videos/introduction_to_hi
ve
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Q&A
Thank you
Back up
Hive Components
Shell Interface: Like the MySQL shell
Driver:
Session handles, fetch, exeucition
Complier:
Prarse,plan,optimzie
Execution Engine:
DAG stage
Run map or reduce
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Motivation
MapReduce Motivation
Data processing: > 1 TB
Massively parallel
Locality
Fault Tolerant
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Hive Usage
hive> show tables;
hive> create table SHAKESPEARE (freq INT,word STRING)
row format delimited fields terminated by ‘\t’ stored as
textfile
hive> load data inpath “shakespeare_freq” into table
shakespeare;
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Hive Usage
hive> load data inpath “shakespeare_freq” into table
shakespeare;
hive> select * from shakespeare where freq>100 sort by
freq asc limit 10;
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Hive Usage @ Facebook
Statistics per day:
4 TB of compressed new data added per day
135TB of compressed data scanned per day
7500+ Hive jobs on per day
Hive simplifies Hadoop:
~200 people/month run jobs on Hadoop/Hive
Analysts (non-engineers) use Hadoop through
Hive
95% of jobs are Hive Jobs
http://www.slideshare.net/cloudera/hw09-hadoop-developmentat-facebook-hive-and-hdfs
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