Re: Unique rows without a key

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От Doug McNaught
Тема Re: Unique rows without a key
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Msg-id m3vglzm73b.fsf@belphigor.mcnaught.org
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Ответ на Re: Unique rows without a key  ("Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu>)
Ответы Re: Unique rows without a key  ("Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu>)
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"Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu> writes:

> > Thanks for your help. However I was thinking more along the lines of using
> > the table itself as the index. Creating a hash column with all the other
> > columns as part of it still significantly increases my table size.
>
> It's not that much of an overhead especially if your table has many
> attributes. There is a function hashname() that will return an
> integer after hashing the text it takes as argument. I didn't find
> any documentation, but seems to work.

If it's not documented I'd worry about it going away in the future.

> Then you just add a unique index on hashval and you are done :-)

And if you get a hash collision?  Going to disallow a perfectly
legitimate and unique row because of it?

-Doug
--
The rain man gave me two cures; he said jump right in,
The first was Texas medicine--the second was just railroad gin,
And like a fool I mixed them, and it strangled up my mind,
Now people just get uglier, and I got no sense of time...          --Dylan

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