Multi-Tenant Magic:

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Multi-Tenant Magic Under the Covers of the
Force.com data Architecture
Craig Weissman Chief Software Architect salesforce
.com
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Safe Harbor Statement
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Securities Litigation Reform Act of 1995 This
presentation may contain forward-looking
statements including but not limited to
statements concerning the potential market for
our existing service offerings and future
offerings. All of our forward looking statements
involve risks, uncertainties and assumptions. If
any such risks or uncertainties materialize or if
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results could differ materially from the results
expressed or implied by the forward-looking
statements we make. The risks and uncertainties
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to - risks associated with possible fluctuations
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interruptions or delays in our service or our Web
hosting, our new business model, our history of
operating losses, the possibility that we will
not remain profitable, breach of our security
measures, the emerging market in which we
operate, our relatively limited operating
history, our ability to hire, retain and motivate
our employees and manage our growth, competition,
our ability to continue to release and gain
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of our service, customer and partner acceptance
of the AppExchange, successful customer
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update these forward-looking statements, except
as required by law.
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True Multi-Tenancy is our Religion
Time
Technology Advances
Major Architectural Shift

• Agenda
• Our Religion
• Virtual Database
• App Model

Business Model Changes
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Single tenant applications lots of waste
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Multi-tenancy benefits are self-evidentBut
isolation is much easier said than done
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Our religion Not all multi-tenant designs are
created equal
Cant we create a separate stack for just
this one customer? I promise its just this one
App
Db
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Introducing the Force.com metadata-driven,
multi-tenant, Internet application platform
Poly- Morphic Application
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Key Architectural Principles

• Stateless AppServers
• Database system of record
• No DDL
• All tables partitioned by OrgId
• Smart PKs, Polymorphic FKs
• Creative de-normalization and pivoting
• Use every RDBMS feature/trick

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Metadata, data, and pivot table structures store
data corresponding to virtual data structures
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The Objects table stores metadata about custom
objects (tables)?
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The Fields table stores metadata about custom
fields (columns)?
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The Data heap table stores all structured data
corresponding to custom objects
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A single slot can store various types of data
that originate from different objects
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The Indexes pivot table manages tenant-specific
selective indexes
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The UniqueFields pivot table facilitates
uniqueness for custom fields
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The Relationships pivot table facilitates
referential integrity and optimizes joins
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All data metadata structures are partitioned to
improve performance and manageability

• Tables hash partitioned by OrgId
• Separate conn pools point to physical hosts
• App tier is also dynamically partitioned by OrgId
• Distributed metadata cache w/transactional
  invalidation

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Application Framework a whole lot for free

• Native Declarative features
• Bulk Processing
• The Recycle Bin
• Full Text Search
• Smart Bulk DML
• Web Services APIs

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Force.coms native Application Framework provides
declarative development, no coding
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Validation rules and simple formulasBusiness
analysts can code these
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Not so simple Rollup-summary fields provide for
easy cross-object summaries
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Force.coms bulk processing optimizations reduce
overhead for data loads
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Data definition processing is optimized to avoid
performance hits or concurrency limits

• Examples
• Sort all records by primary key before attempting
  DML
• Operate on tables in deterministic order
• Slot reallocation for field datatype change
• Deferred calculation for new rollup-summary field
• Background processing of mass changes

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The Recycle Bin Smart Undeletes

• Individual object instances (records)?
• Related object instances (parent/child records)?
• Entire fields and objects(dropped columns and
  tables)?

Restore
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Force.coms full-text search engine

• Asynchronously maintains indexes for all text
  fields
• MRU caches contain recently updated objects
• Optimizes ranking of search result records based
  on current user, modification history, and
  weighting preferences

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Multi-tenant Query Optimization Principles

• Consistent SQL generation across the application
• Deep awareness of pivot table structure
• Flex schema does impose a cost
• Tenant, user, object, fields statistics are
  crucial
• No runaway queries allowed
• Deep integration with the sharing model

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Force.coms query optimizer writes optimal
queries for internal data access operations
Multi-tenant optimizer statistics
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The optimizer considers pre-query selectivity
measurements when writing a query
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Apex Force.coms procedural frontier
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Apex code is stored as metadata, interpreted at
runtime, and cached for scalability
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Apex is deeply integrated with platform features

• Bulk DML
• Email and messaging
• Asynchronous processing (Futures)
• XmlStream / HTTP (RESTful) services classes
• Declarative exposure as new Web Services

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Force.com governs Apex code execution

• Limits on
• CPU
• Memory
• of DML statements
• calculations
• web service calls
• and more

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Unit tests must accompany Apex code

• Required 75 code coverage
• Profiling is built into the platform
• Run during application install
• All tests are run before each platform release by
  us

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Force.com is a proven multi-tenant application
platform that performs and scales
Page Response Time (ms)?
Quarterly Transactions (billions)?
2005
2006
2007
Fiscal Year
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Concluding Remarks

• PaaS is a major architectural shifts
• PaaS is Application focused, high level of
  abstraction
• Force.com is the most mature, proven PaaS
  offering available today
• Optimized for fast, secure, and reliable
  multi-tenant application development and
  deployment