Re: ANTI-JOIN needs table, index scan not possible?

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От Maciek Sakrejda
Тема Re: ANTI-JOIN needs table, index scan not possible?
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Msg-id AANLkTink26wyiPdjdd=Tv-me=XFempCnjsJDGj0wbrhJ@mail.gmail.com
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Ответ на ANTI-JOIN needs table, index scan not possible?  ("hans wulf" <lotu1@gmx.net>)
Ответы Re: ANTI-JOIN needs table, index scan not possible?  ("hans wulf" <lotu1@gmx.net>)
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> I know the table has to be visitied at some point to serve the MVCC, but why so early? Can NOT ESISTS only be fixed
bythe table, because it could miss soemthing otherwise? 

Possibly because the index entries you're anti-joining against may
point to deleted tuples, so you would erroneously omit rows from the
join result if you skip the visibility check?

---
Maciek Sakrejda | System Architect | Truviso

1065 E. Hillsdale Blvd., Suite 215
Foster City, CA 94404
(650) 242-3500 Main
www.truviso.com

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