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(*).
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