Re: Differences between postgres and mysql

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От Mike Nolan
Тема Re: Differences between postgres and mysql
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Msg-id 200402181658.i1IGwk2w013948@gw.tssi.com
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Ответ на Re: Differences between postgres and mysql  (Tom Lane <tgl@sss.pgh.pa.us>)
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> Interesting you should say that, because for years we were getting beat
> up regularly about how poor our ALTER capabilities were compared to
> MySQL's.  Have we really passed them up in ALTER flexibility?  Or is
> there some other limitation you are thinking of?

I wasn't commenting on the flexibility issue, more on performance.

If you add or delete a column doesn't MySQL copy the table to a temp
table then delete the original one and rename the copy?

Try doing that on a table with 25 million rows and you can go to dinner
and a movie while you wait for it to finish.  Try it on a really big
table and you can go to a performance of the Ring Cycle while you're
waiting. (And I mean the Wagner Ring, not Tolkien.)

I didn't comment on the interactive user interfaces.  While there are a
few things about psql that drive me nuts (like the fact that it always does
the edit to a temporary file so it goes away immediately upon exit and
some of the ways \o works, I'm used to using both features in Oracle
to provide a historical trail of my work), mysql can't even repeat a
command (\g) without first re-editing it.
--
Mike Nolan

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