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Friday 3:15 p.m.–4 p.m.

The SQLAlchemy Session - In Depth

Mike Bayer

Audience level:
Intermediate
Category:
Databases/NoSQL

Description

A detailed walkthrough of SQLAlchemy's Session, describing the rationale for its existence, its driving philosophies, and finally a walkthrough of Session lifecycle through the use of an animated diagram. We'll cover how the relational database refers to database rows within a transaction, and how the Session has over the years developed a tight, proxied integration with this lifecycle.

Abstract

  • Intro

  • The problem of object persistence

  • Persistence Strategies

    • ad-hoc

    • managed

  • Transactions

    • Isolation

    • autocommit

  • SQLAlchemy Patterns

    • Identity map

    • unit of work

    • proxy pattern

  • History

    • "objectstore" / thread local

    • Session

    • autoflush / autoexpire / transactional

  • Influences

    • Fowler

    • Python ORMs

      • SQLObject
      • Storm

    • Hibernate

    • JPA / JSR-220

  • Detailed Demo

    • Intro to live animation demo

    • Description of areas

      • object state

      • database

      • connection / isolated transaction

      • session

      • session transaction

      • new, dirty, deleted, identity map

    • Step by step

      • transient objects

      • populate attributes

      • pending objects

      • flush

      • population of isolated rows / sync of attributes

      • persistent objects

      • commit isolated rows to permanent

      • expire

      • teardown

      • lazy refresh

      • lazy load

      • modify attribute

      • flush

      • update isolated rows

      • commit isolated rows to permanent

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