Re: *sigh*
От | Christopher Browne |
---|---|
Тема | Re: *sigh* |
Дата | |
Msg-id | m3r7zqa42j.fsf@wolfe.cbbrowne.com обсуждение исходный текст |
Ответ на | *sigh* (Thomas Zehetbauer <thomasz@hostmaster.org>) |
Список | pgsql-hackers |
Oops! mendola@bigfoot.com (Gaetano Mendola) was seen spray-painting on a wall: > Doug McNaught wrote: >> Randolf Richardson <rr@8x.ca> writes: >> >>> What about adding a "total number of rows" value to the >>> internal header of each table which gets incremented/decremented >>> after each row is INSERT/DELETE has been committed. This way, a >>> generic "count(*)" by itself could simply return this value without >>> any delay at all. >> Because different sessions have a (validly) different concept of what >> that number should be, due to MVCC. > > The count(*) information can be revisioned too, am I wrong ? I'm able to > create a trigger that store the count(*) information in a special table, > why not implement the same in a way "builded in" ? You could do this; the cost would be pretty high, as there would be an extra table update done every time rows were inserted or deleted. Doing it on _every_ table would be a heavy overhead that is not worthwhile. What might make sense would be to set up triggers to do this on those large tables where you frequently need COUNT(*). -- "cbbrowne","@","cbbrowne.com" http://www.ntlug.org/~cbbrowne/lisp.html As of next month, MACLISP "/" will be flushed in favor of "\". Please update the WORLD.
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