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Re: ANTI-JOIN needs table, index scan not possible? - Mailing list pgsql-performance

From Maciek Sakrejda
Subject Re: ANTI-JOIN needs table, index scan not possible?
Date
Msg-id AANLkTink26wyiPdjdd=Tv-me=XFempCnjsJDGj0wbrhJ@mail.gmail.com
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In response to ANTI-JOIN needs table, index scan not possible?  ("hans wulf" <lotu1@gmx.net>)
Responses 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
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(650) 242-3500 Main
www.truviso.com

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