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List:       postgresql-general
Subject:    Re: [HACKERS] [PATCH] Space reservation v02
From:       Robert Haas <robertmhaas () gmail ! com>
Date:       2009-01-31 21:21:30
Message-ID: B9A4A833-C199-402A-8F6C-12F21AB10DD8 () gmail ! com
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On Jan 31, 2009, at 2:44 PM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com 
 > wrote:

> Robert Haas wrote:
>> People who upgrade via pg_dump will automatically get the new and
>> improved widget type because that is what is now called widget.  But
>> people who in-place upgrade will end up with the old_shitty_widget
>> type.  Then you just run some dead simple postupdate script that goes
>> through and issues ALTER TABLE commands to change each
>> old_shitty_widget column to a widget column.
>
> Altering column type with ALTER TABLE needs to exclusively-lock and  
> rewrite the whole table, so you might as well pg_dump+restore that  
> table.

Not at all.  Lots of DDL operations take table locks, but they're  
still a lot more convenient than dump+restore. Think dependencies.

A stickier wicket is how to handle functions and views that depend on  
the old type, so maybe this isn't quite as clean as I thought.

...Robert

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