Fairly good idea IMHO, especially considering Christopher's point about the unlikeliness of needing an exact count anyway.
Regards, Christoph > > How about: > > Implement a function "estimated_count" that can be used instead of > "count". It could use something like the algorithm in > src/backend/commands/analyze.c to get a reasonably accurate psuedo count > quickly. > > The advantage of this approach is that "count" still means (exact)count > (for your xact snapshot anyway). Then the situation becomes: > > Want a fast count? - use estimated_count(*) > Want an exact count - use count(*) > > regards > > Mark > > Christopher Browne wrote: > > >For a small table, it will be cheaper to walk through and calculate > >count(*) directly from the tuples themselves. > > > >The situation where it may be worthwhile to do this is a table which > >is rather large (thus count(*) is expensive) where there is some > >special reason to truly care how many rows there are in the table. > >For _most_ tables, it seems unlikely that this will be true. For > >_most_ tables, it is absolutely not worth the cost of tracking the > >information. > > > > ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
