Introduction to Azure Data Lake and U-SQL for SQL users (SQL Saturday 635)

Introduction to Azure Data Lake
and U-SQL for SQL users
Michael Rys (@MikeDoesBigData)
John Morcos
Microsoft Corp

The Traditional Data Warehouse
2
Data sourcesNon-relational data

The Data Lake approach
Ingest all data
regardless of
requirements
Store all data
in native format
without schema
definition
Do analysis
Using analytic
engines like Hadoop
Interactive queries
Batch queries
Machine Learning
Data warehouse
Real-time analytics
Devices

WebHDFS
.NET, SQL, Python, R
scaled out by U-SQL
ADL Analytics HDInsight
ADL Store
HiveAnalytics
Storage
Azure Data Lake (Store, HDInsight, Analytics)

Some sample use cases
Digital Crime Unit – Analyze complex attack patterns
to understand BotNets and to predict and mitigate
future attacks by analyzing log records with
complex custom algorithms
Image Processing – Large-scale image feature
extraction and classification using custom code
Shopping Recommendation – Complex pattern
analysis and prediction over shopping records
using proprietary algorithms
Characteristics
of Big Data
Analytics
Requires processing
of any type of data
Allow use of custom
algorithms
Scale to any size and
be efficient

Status Quo:
SQL for
Big Data
 Declarativity does scaling and
parallelization for you
 Extensibility is bolted on and
not “native”
 hard to work with anything other than
structured data
 difficult to extend with custom code

Status Quo:
Programming
Languages for
Big Data
 Extensibility through custom code
is “native”
 Declarativity is bolted on and
not “native”
 User often has to
care about scale and performance
 SQL is 2nd class within string
 Often no code reuse/
sharing across queries

Why U-SQL?
 Declarativity and Extensibility are
equally native to the language!
Get benefits of both!
Makes it easy for you by unifying:
• Declarative and imperative
• Unstructured and structured data processing
• Local and remote Queries
• Increase productivity and agility from Day 1 and
at Day 100 for YOU!
Scales out your
custom imperative
Code (written in .NET,
Python, R, and more
to come) in a
declarative SQL-
based framework

The origins
of U-SQL
SCOPE – Microsoft’s internal
Big Data language
• SQL and C# integration model
• Optimization and Scaling model
• Runs 100’000s of jobs daily
Hive
• Complex data types (Maps, Arrays)
• Data format alignment for text files
T-SQL/ANSI SQL
• Many of the SQL capabilities (windowing functions, meta
data model etc.)

Query data where it lives
Easily query data in multiple Azure data stores without moving it to a single store
Benefits
• Avoid moving large amounts of data across the
network between stores
• Single view of data irrespective of physical location
• Minimize data proliferation issues caused by
maintaining multiple copies
• Single query language for all data
• Each data store maintains its own sovereignty
• Design choices based on the need
• Push SQL expressions to remote SQL sources
• Projections
• Filters
• Joins
U-SQL
Query
Query
Azure
Storage Blobs
Azure SQL
in VMs
Azure
SQL DB
Azure Data
Lake Analytics
Azure
SQL Data Warehouse
Azure
Data Lake Storage

U-SQL offers Advanced Analytics
Extensions for
Massively Parallel
processing
• Python
• R
Built-in Cognitive
capabilities
• Imaging
• Detecting Objects
• Detecting Emotion in Faces
• Detecting Text (OCR)
• Text Analysis
• Key Phrase Extraction
• Sentiment Analysis

Demo
Show me U-SQL!
https://github.com/Azure/usql/tree/master/Examples/TweetAnalysis

Expression-flow
Programming Style
Automatic "in-lining" of U-SQL expressions –
whole script leads to a single execution model.
Execution plan that is optimized out-of-the-
box and w/o user intervention.
Per job and user driven level of parallelization.
Detail visibility into execution steps, for
debugging.
Heatmap like functionality to identify
performance bottlenecks.

U-SQL extensibility
Extend U-SQL with C#/.NET, Python, R
Built-in operators,
function, aggregates
C# expressions (in SELECT expressions)
User-defined aggregates (UDAGGs)
User-defined functions (UDFs)
User-defined operators (UDOs)

• Schema on Read
• Write to File
• Built-in and custom Extractors and
Outputters
• ADL Storage and Azure Blob
Storage
“Unstructured” Files
EXTRACT Expression
@s = EXTRACT a string, b int
FROM "filepath/file.csv"
USING Extractors.Csv(encoding: Encoding.Unicode);
• Built-in Extractors: Csv, Tsv, Text with lots of options
• Custom Extractors: e.g., JSON, XML, etc. (see http://usql.io)
OUTPUT Expression
OUTPUT @s
TO "filepath/file.csv"
USING Outputters.Csv();
• Built-in Outputters: Csv, Tsv, Text
• Custom Outputters: e.g., JSON, XML, etc. (see http://usql.io)
Filepath URIs
• Relative URI to default ADL Storage account: "filepath/file.csv"
• Absolute URIs:
• ADLS: "adl://account.azuredatalakestore.net/filepath/file.csv"
• WASB: "wasb://container@account/filepath/file.csv"

Show me File Sets!

• Simple Patterns
• Virtual Columns
• Only on EXTRACT for now
File Sets Simple pattern language on filename and path
@pattern string =
"/input/{date:yyyy}/{date:MM}/{date:dd}/{*}.{suffix}";
• Binds two columns date and suffix
• Wildcards the filename
• Limits on number of files
(Current limit 800-3000 is increased in special preview)
Virtual columns
EXTRACT
name string
, suffix string // virtual column
, date DateTime // virtual column
FROM @pattern
USING Extractors.Csv();
• Refer to virtual columns in query predicates to get partition
elimination
• Warning gets raised if no partition elimination was found

Create
shareable data
and code

Meta Data Object Model
ADLA Account/Catalog
Database
Schema
[1,n]
[1,n]
[0,n]
tables views TVFs
C# Fns C# UDAgg
Clustered
Index
partitions
C#
Assemblies
C# Extractors
Data
Source
C# Reducers
C# Processors
C# Combiners
C# Outputters
Ext. tables
User
objects
Refers toContains Implemented
and named by
Procedures
Creden-
tials
MD
Name
C# Name
C# Applier
Table Types
Legend
Statistics
C# UDTs
Packages

• Naming
• Discovery
• Sharing
• Securing
U-SQL Catalog Naming
• Default Database and Schema context: master.dbo
• Quote identifiers with []: [my table]
• Stores data in ADL Storage /catalog folder
Discovery
• Visual Studio Server Explorer
• Azure Data Lake Analytics Portal
• SDKs and Azure Powershell commands
Sharing
• Within an Azure Data Lake Analytics account
• Across ADLA accounts that share same Azure Active Directory:
• Referencing Assemblies
• Calling TVFs and referencing tables and views
• Inserting into Tables
Securing
• Secured with AAD principals at catalog and Database level

• Views for simple cases
• TVFs for parameterization and
most cases
VIEWs and TVFs Views
CREATE VIEW V AS EXTRACT…
CREATE VIEW V AS SELECT …
• Cannot contain user-defined objects (e.g. UDF or UDOs)!
• Will be inlined
Table-Valued Functions (TVFs)
CREATE FUNCTION F (@arg string = "default")
RETURNS @res [TABLE ( … )]
AS BEGIN … @res = … END;
• Provides parameterization
• One or more results
• Can contain multiple statements
• Can contain user-code (needs assembly reference)
• Will always be inlined
• Infers schema or checks against specified return schema

Procedures
CREATE PROCEDURE P (@arg string = "default“) AS
BEGIN
…;
CREATE TABLE T …;
OUTPUT @res TO …;
INSERT INTO T …;
END;
• Provides parameterization
• No result but writes into file or table
• Can contain multiple statements
• Can contain user-code (needs assembly reference)
• Will always be inlined
• Can contain DDL (but no CREATE, DROP
FUNCTION/PROCEDURE)

• CREATE TABLE
• CREATE TABLE AS SELECT
Tables
CREATE TABLE T (col1 int
, col2 string
, col3 SQL.MAP<string,string>
, INDEX idx CLUSTERED (col2 ASC)
PARTITION BY (col1)
DISTRIBUTED BY HASH (driver_id)
);
• Structured Data, built-in Data types only (no UDTs)
• Clustered Index (needs to be specified): row-oriented
• Fine-grained distribution (needs to be specified):
• HASH, DIRECT HASH, RANGE, ROUND ROBIN
• Addressable Partitions (optional)
CREATE TABLE T (INDEX idx CLUSTERED …) AS SELECT …;
CREATE TABLE T (INDEX idx CLUSTERED …) AS EXTRACT…;
CREATE TABLE T (INDEX idx CLUSTERED …) AS myTVF(DEFAULT);
• Infer the schema from the query
• Still requires index and distribution (does not support partitioning)

When to use
Tables
Benefits of Table clustering and distribution
• Faster lookup of data provided by distribution and clustering when right
distribution/cluster is chosen
• Data distribution provides better localized scale out
• Used for filters, joins and grouping
Benefits of Table partitioning
• Provides data life cycle management (“expire” old partitions)
• Partial re-computation of data at partition level
• Query predicates can provide partition elimination
Do not use when…
• No filters, joins and grouping
• No reuse of the data for future queries
If in doubt: use sampling (e.g., SAMPLE ANY(x)) and test.

• ALTER TABLE ADD/DROP
COLUMN
Evolving Tables
ALTER TABLE T ADD COLUMN eventName string;
ALTER TABLE T DROP COLUMN col3;
ALTER TABLE T ADD COLUMN result string, clientId
string, payload int?;
ALTER TABLE T DROP COLUMN clientId, result;
• Meta-data only operation
• Existing rows will get
• Non-nullable types: C# data type default value (e.g., int will
be 0)
• Nullable types: null

Let’s do
some SQL
with U-SQL!

U-SQL
Joins
Join operators
• INNER JOIN
• LEFT or RIGHT or FULL OUTER JOIN
• CROSS JOIN
• SEMIJOIN
• equivalent to IN subquery
• ANTISEMIJOIN
• Equivalent to NOT IN subquery
Notes
• ON clause comparisons need to be of the simple form:
rowset.column == rowset.column
or AND conjunctions of the simple equality comparison
• If a comparand is not a column, wrap it into a column in a previous
SELECT
• If the comparison operation is not ==, put it into the WHERE clause
• turn the join into a CROSS JOIN if no equality comparison
Reason: Syntax calls out which joins are efficient

U-SQL
Analytics
Windowing Expression
Window_Function_Call 'OVER' '('
[ Over_Partition_By_Clause ]
[ Order_By_Clause ]
[ Row _Clause ]
')'.
Window_Function_Call :=
Aggregate_Function_Call
| Analytic_Function_Call
| Ranking_Function_Call.
Windowing Aggregate Functions
ANY_VALUE, AVG, COUNT, MAX, MIN, SUM, STDEV, STDEVP, VAR, VARP
Analytics Functions
CUME_DIST, FIRST_VALUE, LAST_VALUE, PERCENTILE_CONT,
PERCENTILE_DISC, PERCENT_RANK, LEAD, LAG
Ranking Functions
DENSE_RANK, NTILE, RANK, ROW_NUMBER

“Top 5”s
Surprises for
SQL Users
• AS is not as
• C# keywords and SQL keywords overlap
• Costly to make case-insensitive -> Better
build capabilities than tinker with syntax
• = != ==
• Remember: C# expression language
• null IS NOT NULL
• C# nulls are two-valued
• PROCEDURES but no WHILE
• No UPDATE, DELETE, nor MERGE (yet)

U-SQL Language Philosophy
Declarative Query and Transformation Language:
• Uses SQL’s SELECT FROM WHERE with GROUP
BY/Aggregation, Joins, SQL Analytics functions
• Optimizable, Scalable
Expression-flow programming style:
• Easy to use functional lambda composition
• Composable, globally optimizable
Operates on Unstructured & Structured Data
• Schema on read over files
• Relational metadata objects (e.g. database, table)
Extensible from ground up:
• Type system is based on .NET
• Expression language IS C#
• User-defined functions (U-SQL and C#)
• User-defined Aggregators (C#)
• User-defined Operators (UDO) (C#, Python, R)
U-SQL provides the Parallelization and Scale-out
Framework for Usercode
• EXTRACTOR, OUTPUTTER, PROCESSOR, REDUCER,
COMBINER, APPLIER
Federated query across distributed data sources
REFERENCE MyDB.MyAssembly;
CREATE TABLE T( cid int, first_order DateTime
, last_order DateTime, order_count int
, order_amount float, ... );
@o = EXTRACT oid int, cid int, odate DateTime, amount float
FROM "/input/orders.txt"
@c = EXTRACT cid int, name string, city string
FROM "/input/customers.txt"
@j = SELECT c.cid, MIN(o.odate) AS firstorder
, MAX(o.date) AS lastorder, COUNT(o.oid) AS ordercnt
, AGG<MyAgg.MySum>(c.amount) AS totalamount
FROM @c AS c LEFT OUTER JOIN @o AS o ON c.cid == o.cid
WHERE c.city.StartsWith("New")
&& MyNamespace.MyFunction(o.odate) > 10
GROUP BY c.cid;
OUTPUT @j TO "/output/result.txt"
USING new MyData.Write();
INSERT INTO T SELECT * FROM @j;

Scales out your data processing over large amount of data
Unifies natively SQL’s declarativity and PL’s extensibility
Unifies querying structured and unstructured data
Unifies querying Data Lake and SQL Server (in Azure) data
Increase productivity & agility on Day 1 & 100 for YOU!
Sign up for an Azure Data Lake account at
http://www.azure.com/datalake and give us your feedback via
http://aka.ms/adlfeedback!
This is why U-SQL!

Additional
Resources
Blogs, presentations and community pages:
http://aka.ms/AzureDataLake
http://usql.io (U-SQL Github)
http://blogs.msdn.microsoft.com/mrys/
http://blogs.msdn.microsoft.com/azuredatalake/
http://www.slideshare.net/MichaelRys
Documentation, articles, and videos:
http://aka.ms/usql_reference
https://azure.microsoft.com/en-
us/documentation/services/data-lake-analytics/
https://msdn.microsoft.com/en-us/magazine/mt614251
https://channel9.msdn.com/Search?term=U-SQL#ch9Search
https://www.youtube.com/results?search_query=U-SQL
ADL forums and feedback
http://aka.ms/adlfeedback
https://social.msdn.microsoft.com/Forums/azure/en-
US/home?forum=AzureDataLake
http://stackoverflow.com/questions/tagged/u-sql
• Continue your education
at Microsoft Virtual
Academy online.

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Introduction to Azure Data Lake and U-SQL for SQL users (SQL Saturday 635)

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