Scaling the data tier minimize db transactions auto

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Unformatted text preview: e use of prepared statements and bind variables 22 © 2 0 0 6 e B a y In c . Scaling the Data Tier: Minimize DB Transactions • Auto-commit for vast majority of DB writes • Absolutely no client side transactions nc . – Single database transactions managed through anonymous PL/SQL blocks. – No distributed transactions. ,I • How do we pull it off? ay – Careful ordering of DB operations – Recovery through • A s y n c h r o n o u s r e c o v e r y e v e n ts • R e c o n c ilia tio n b a tc h • Rationale – – – – eB • F a ilo v e r to a s y n c flo w Avoid deadlocks Avoid coupling availability Update concurrency Seamless handling of splits 23 © 2 0 0 6 e B a y In c . eB ay ,I nc . Scaling the Application Tier Scaling the Application Tier – Overview nc – Segmentation by function. – Horizontal load-balancing within functions. . • Spread the Load • Minimize dependencies eB • Virtualize data access ay ,I – Between applications – Between functional areas – From applications to data tier resources 25 © 2 0 0 6 e B a y In c . Scaling the Application Tier – Massively Scaling J2EE • Step 1 - Throw out most of J2EE – eBay scales on servlets and a rewritten connection pool. nc . • Step 2 – Keep Application Tier Completely Stateless ,I – No session state in application tier – Transient state maintained in cookie or scratch database • Step 3 – Cache Where Possible eB ay – Cache common metadata across requests, with sophisticated cache refresh procedures – Cache reload from local storage – Cache request data in ThreadLocal 26 © 2 0 0 6 e B a y In c . Scaling the Application Tier – Tiered Application Model nc XSL ,I Presentation Tier . • Strictly partition application into tiers •Presentation •Business •Integration Command (View) Integration Tier BO/BOF Business Logic DO/DAO Data Access Layer (DAL) eB Business Tier ay AO/AOF (View) XML Model Building Logic 27 © 2 0 0 6 e B a y In c . Scaling the Application Tier – Data Access Layer (DAL) • W h a t is th e D A L ? ,I nc . – eBay’s i...
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This note was uploaded on 10/11/2012 for the course INFORMATIO IS taught by Professor Various during the Spring '11 term at CSU Northridge.

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