From: | "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au> |
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To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Stephan Szabo" <sszabo(at)megazone23(dot)bigpanda(dot)com> |
Cc: | "Hackers" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [SQL] how to change the type |
Date: | 2001-12-10 02:32:56 |
Message-ID: | GNELIHDDFBOCMGBFGEFOAELBCAAA.chriskl@familyhealth.com.au |
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Thread: | |
Lists: | pgsql-hackers pgsql-sql |
> char(N) does store the trailing spaces, so altering N would give
> unwanted results: again, existing values would read out with the old
> width until updated. You could fix this by issuing
>
> UPDATE tab SET col = col
>
> after tweaking the pg_attribute.atttypmod value. (AFAICS, any "clean"
> implementation would have to do just that internally, with the same
> unpleasant space and speed implications as we've discussed for DROP
> COLUMN.)
Can I take this opportunity to give my little thought on operations like
these (alter column type, drop column, etc.?)
If the DBA had to issue these commands every 5 minutes, then the speed and
space implications would be bad, yeah. However, if all I want to do is drop
a column once every 6 months, then I don't really care that the operation
might take a minute and might consume lots of disk space...
Chris
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