Based on slides developed by

1
ICS 214B Transaction Processing and Distributed
Data Management
Lecture 17 Providing Database as a
Service Professor Chen Li

• Based on slides developed by
• Hakan Hacigumus, Bala Iyer, and Sharad Mehrotra
• ICDE 2002, San Jose, CA, USA

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Talk Outline

• Software as a Service
• Database as a Service
• NetDB2 System
• Challenges for Database as a Service
• User Interface Issues
• Performance Issues
• Data Privacy Issues
• Data Encryption in DBMSs for Data Privacy
• Conclusion

3
Software as a Service

• Get
• what you need
• when you need
• Pay
• what you use
• Dont worry
• how to deploy, implement, maintain, upgrade

4
Software as a Service

• Driving forces to paradigm shift
• Faster, cheaper, more accessible networks
• Rise of distributed architectures
• Virtualization in server and storage technologies
• Established e-business infrastructures
• Hardware/Software is not the largest in total
  cost of ownership
• User Operations 46
• Technical Support 24
• Capital Cost (HW/SW) 21 (Source Gartner
  Group)
• Hardware, software, network costs have been
  decreasing more sharply than personnel cost

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Software as a Service

• Already in the market as
• storage services, disaster recovery services,
  e-mail services, rent-a-spreadsheet services etc.
• Sun ONE, Oracle Online Services, Microsoft .NET
  My Services etc.
• Why not Database as a Service ?

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Database as a Service - Why?

• Organizations need data management
• DBMSs are complex systems to deploy, setup,
  maintain
• requires highly skilled people (DBAs etc.) with
  high cost

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Database as a Service - Offerings

• Inherits all advantages of software as a service,
  plus
• Service provider allows mechanisms to
• create, store, access databases
• DB management transferred to service provider for
• backup, administration, restoration, space
  management, upgrades
• Clients use the services providers HW, SW,
  personnel instead of their own

8
NetDB2 - Database Service Provision

• Developed in collaboration with University of
  California, Irvine and IBM
• Deployed on the Internet over a year ago
• Been used by 15 universities and more than 2500
  students to help teaching database classes
• Currently offered through IBM Scholars Program

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NetDB2 System Architecture

• Three tier architecture
• Client - as thin as possible - just a browser
• Java based implementation
• Backed by fail-over solutions
• Allows expansions and user driven integration for
  application development

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Database as a Service - Issues

• Issues to address
• User Interface
• Performance
• Data Privacy

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User Interface

• Simple yet powerful
• supports SQL queries, scripts, UDFs, stored
  procedures, metadata, data upload
• Consistent
• Region-based composition
• Expansion/Integration
• User defined interfaces

12
Performance

• Interaction in a different medium - network
• Performance should -at least- match what we have
  already
• Experimented with TPC-H database and queries

13
Data Privacy

• Users give control of their data to service
  provider
• Attacks on stored data is a well known problem
• So, they need data security in place
• Security of data over the network is well studied
• SSL,TSL
• Establish security for stored data
• even it is stolen should not make sense ?
  Encryption !

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Encryption Alternatives

• Implementation Level
• Software v.s. Hardware encryption
• Granularity of Data
• Field (Attribute) level
• Row (Record) level
• (Disk) Page level

?
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Encryption Alternatives (2)

• Field level encryption
• Pros
• Easier to implement and integrate
• Flexible
• Allows selective encryption, reduces number of
  bytes to encrypt/decrypt
• Cons
• Increases encryption overhead significantly due
  to invocation cost
• Data size expansion (for block cipher algorithms)
• Current optimization technologies do not handle
  foreign functions well

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Encryption Alternatives (3)

• Row level encryption
• Pros
• Reduces the data size expansion problem
• Reduces invocation cost
• Better security because of total encryption
• Cons
• Does not allow selective encryption, increases
  the number of bytes to encrypt/decrypt
• Implementation and integration can be hard when
  row functions are not supported

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Encryption Alternatives (4)

• Page level encryption
• Pros
• Significantly reduces encryption/decryption
  overhead due to reduced invocation cost
• Eliminates data size expansion problem (for block
  ciphers)
• Better security because of total encryption
• Cons
• Implementation and integration is not
  straightforward
• Increases the number of bytes to encrypt/decrypt
  each time
• Higher update/delete cost, requires re-encryption
  of all affected pages

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Encryption Alternatives Experiments

• Experimented with TPC-H database and queries
• Encryption scheme alternatives (V evaluated,
  not evaluated)

Data Granularity Implementation Field
Level Row Level Page Level Software Encryption
V Hardware Encryption
V V
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Software - Field Level Encryption

• Block Cipher Algorithm - Blowfish
• Implemented as foreign function (UDF)
• Sample insert
• insert into lineitem (discount) values
  (encrypt(10,key))
• Sample select
• select decrypt(discount,key) from lineitem where
  custid 300

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Software - Field Level Encryption (2)

• Creator supplies the key
• Unauthorized person can not get hold of the key
• protection even from the service provider at some
  level
• User can easily implement different encryption
  algorithm and check that into the system
• different encryption algorithm/key can be used
  for different fields

21
Software - Field Level Encryption (3)

• TPC-H queries, except Q1
• Only one field (l_discount of lineitem table)
  encrypted
• Introduced very large overhead

• Q1 excluded

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TPC-H Query 1

• Problem Multiple decryption on same field
• select
• l_returnflag, l_linestatus,
• sum(l_quantity) as sum_qty,
• sum(l_extendedprice) as sum_base_price,
• sum(l_extendedprice (1 - l_discount)) as
  sum_disc_price,
• sum(l_extendedprice (1 - l_discount) (1
  l_tax)) as sum_charge,
• avg(l_quantity) as avg_qty,
• avg(l_extendedprice) as avg_price,
• avg(l_discount) as avg_disc,
• count() as count_order
• from tpcd.lineitem
• where l_shipdate lt date ('1998-12-01') - 90 day
• group by l_returnflag, l_linestatus
• order by l_returnflag, l_linestatus

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Query Rewrite to Improve Performance

• Problem Multiple decryption on same field (e.g.,
  TPC-H Q1)
• CSE based algorithm to eliminate redundant
  decryptions
• Use temporary view

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Hardware - Row Level Encryption

• Specialized hardware IBM S/390 Cryptographic
  Coprocessor under IBM OS/390
• editproc facility
• invoked for whole row
• upon read/write request, encrypt/decrypt is
  invoked from hardware for the row

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SW Field Level v.s. HW Row Level

• Experimented on TPC-H Q1
• Software Field Level Only one field is encrypted
• Hardware Row Level All fields are encrypted

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Hardware - Page Level Encryption

• Page level encryption is simulated
• It gives significant improvement due to reduction
  in start-up cost

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Conclusion

• Database as a Service is a new model to
  alleviates the need to
• hire professionals
• purchase expensive hardware/software
• deal with administrative and maintenance tasks
• It is viable model and can emerge as a successful
  offering
• Encryption is a solution for privacy -the most
  important issue-
• Hardware encryption has a clear superiority over
  software
• Hardware makes encryption practical for databases
• There are trade-offs for granularity of data