Re: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)
Bruce Momjian <maillist@candle.pha.pa.us>
From: Bruce Momjian <maillist@candle.pha.pa.us>
To: taral@mail.utexas.edu (Taral)
Cc: hackers@postgreSQL.org
Date: 1998-10-02T16:40:56Z
Lists: pgsql-hackers, pgsql-general
[Charset iso-8859-1 unsupported, filtering to ASCII...] > > This is interesting. Check CNF size and DNF size. Choose smallest. > > CNF uses existing code, DNF converts to UNIONs. How do you return the > > proper rows with/without proper duplicates? > > Create a temporary oid hash? (for each table selected on, I guess) > > Taral > What I did with indexes was to run the previous OR clause index restrictions through the qualification code, and make sure it failed, but I am not sure how that is going to work with a more complex WHERE clause. Perhaps I need to restrict this to just simple cases of constants, which are easy to pick out an run through. Doing this with joins would be very hard, I think. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026