South New and Old

A talk I gave at DjangoCon Europe 2010

Transcript

1. new and old
   south
   Andrew Godwin
   djangocon.eu 2010
   

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2. It's been almost 2 years.
   Lots has happened.
   

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3. Migrations? Eh?
   A bit like a VCS, but for database schemas.
   

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4. The Beginning
   

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5. 1-make_tables.sql
   2-add_profile.sql
   

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6. YOU ARE AT
   VERSION
   2
   1-make_tables.sql
   2-add_profile.sql
   

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7. 1-make_tables.sql
   2-add_profile.sql
   3-remove_pony.sql
   1-make_tables.sql
   2-add_profile.sql
   4-add_postcode.sql
   

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8. 1-make_tables.sql
   2-add_profile.sql
   3-remove_pony.sql
   1-make_tables.sql
   2-add_profile.sql
   4-add_postcode.sql
   YOU ARE AT
   VERSION
   3 YOU ARE AT
   VERSION
   4
   

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9. 1-make_tables.sql
   2-add_profile.sql
   3-remove_pony.sql
   1-make_tables.sql
   2-add_profile.sql
   4-add_postcode.sql
   YOU ARE AT
   VERSION
   3 YOU ARE AT
   VERSION
   4
   3-remove_pony.sql
   4-add_postcode.sql
   

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10. Oracle MySQL
    PostgreSQL
    MSSQL
    SQLite
    

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11. The Early Days
    

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12. Adding tables
    Deleting tables
    Everything else useful
    

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13. 3-remove_pony.sql
    1-make_tables.sql
    2-add_profile.sql
    4-add_postcode.sql
    

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14. Uh-oh, publicity
    

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15. Closing this, as it's unlikely we'll write a
    model history tracker in the near future,
    and django-evolution does this well -
    no need to reinvent the wheel in that area.
    “
    “
    

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16. Feature Creep
    (of the good sort)
    

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17. start_field_re = re.compile(r'\s*%s\s*=\s*(.*)' % field.name)
    for line in source[0]:
    # if the field was found during a previous iteration,
    # we're here because the field spans across multiple lines
    # append the current line and try again
    

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18. cms.0001_initial
    cms.0002_auto_start
    picture.0001_initial
    file.0001_initial
    flash.0001_initial
    link.0001_initial
    snippet.0001_initial
    video.0001_initial twitter.0001_initial
    cms.0003_remove_placeholder
    cms.0004_textobjects
    cms.0005_mptt_added_to_plugins
    cms.0006_apphook
    text.0001_initial cms.0007_apphook_longer
    cms.0008_redirects
    cms.0009_added_meta_fields
    cms.0010_5char_language
    cms.0011_title_overwrites
    cms.0012_publisher
    cms.0013_site_copy
    file.0003_publisher
    text.0003_publisher
    picture.0004_publisher
    googlemap.0001_initial
    link.0005_publisher
    flash.0003_publisher
    snippet.0002_publisher
    cms.0014_sites_removed
    cms.0015_modified_by_added
    cms.0016_author_copy
    cms.0017_author_removed
    cms.0018_site_permissions
    cms.0019_public_table_renames
    file.0004_table_rename
    cms.0020_advanced_permissions
    picture.0006_float_added teaser.0001_initial
    text.0004_table_rename
    flash.0004_table_rename link.0006_table_rename snippet.0003_table_rename
    googlemap.0002_table_rename
    picture.0005_table_rename
    cms.0021_publisher2
    picture.0007_publisher2
    cms.0022_login_required_added
    teaser.0002_publisher2
    cms.0023_plugin_table_naming_function_changed
    text.0002_freeze
    text.0005_publisher2
    picture.0002_link_rename
    picture.0003_freeze
    picture.0008_longdesc_added
    file.0002_freeze
    file.0005_publisher2
    flash.0002_freeze
    flash.0005_publisher2
    link.0002_link_rename
    link.0003_page_link
    link.0004_larger_link_names
    link.0007_publisher2
    link.0008_mailto
    snippet.0004_publisher2
    snippet.0005_template_added
    googlemap.0006_publisher2
    googlemap.0007_latlng
    googlemap.0008_routeplaner
    googlemap.0009_routeplaner_title
    video.0002_color_mute_controller
    video.0003_newplayer_step1
    video.0004_newplayer_step2
    video.0005_newplayer_step3
    video.0006_newplayer_step4
    video.0007_newplayer_step5
    inherit.0001_initial
    inherit.0002_fieldchanges
    

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19. Model Freezing
    

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20. Historical ORM access
    Automatic change detection
    ‘Improved’ model parsing
    

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21. Sanity Dawns
    

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22. Introspection
    Magically supports custom fields
    Prevents hideous migration failure
    

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23. SQLite
    Make new table
    Copy data from old table
    Delete old table
    Rename new table
    

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24. Signals
    Speed
    Simplicity
    

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25. 1.0
    

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26. MultiDB?
    Non-relational?
    Renames!
    

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27. Organic Growth
    But it's still cleanly separated
    

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28. Database
    Backend
    Dependency/
    Ordering
    Engine
    Migration
    Runner
    Auto-
    detector
    

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29. The Future
    

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30. Database
    Backend
    Dependency/
    Ordering
    Engine
    South in future
    ???
    Migration
    Runner
    Auto-
    detector
    

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31. The Ultimate Goal
    

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32. Andrew Godwin
    Fin.
    www.aeracode.org
    @andrewgodwin
    

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33. Andrew Godwin
    Fin.
    www.aeracode.org
    @andrewgodwin
    

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