Re: [HACKERS] performance question

2001-08-28 Thread Reinoud van Leeuwen
> On Tue, 28 Aug 2001, Reinoud van Leeuwen wrote: > >> Can somebody explain to me: >> >> > radius=# explain select count (radiuspk) from radius ; >> > NOTICE: QUERY PLAN: >> > >> > Aggregate (cost=12839.79..12839.79 rows=1 width=8) >> > -> Seq Scan on radius (cost=0.00..11843.43 rows=39854

Re: [HACKERS] performance question

2001-08-28 Thread Stephan Szabo
On Tue, 28 Aug 2001, Reinoud van Leeuwen wrote: > Can somebody explain to me: > > > radius=# explain select count (radiuspk) from radius ; > > NOTICE: QUERY PLAN: > > > > Aggregate (cost=12839.79..12839.79 rows=1 width=8) > > -> Seq Scan on radius (cost=0.00..11843.43 rows=398543 width=8)

Re: [HACKERS] performance question

2001-08-28 Thread Peter Eisentraut
Reinoud van Leeuwen writes: > > radius=# select count (radiuspk) from radius ; > > count > > > > 398543 > > (1 row) > > This query takes about 3 seconds. But the query plan *already* knows the > number of rows ("rows=398543"). This is only an estimate which is only updated by VACUU

[HACKERS] performance question

2001-08-28 Thread Reinoud van Leeuwen
Can somebody explain to me: > radius=# explain select count (radiuspk) from radius ; > NOTICE: QUERY PLAN: > > Aggregate (cost=12839.79..12839.79 rows=1 width=8) > -> Seq Scan on radius (cost=0.00..11843.43 rows=398543 width=8) > > EXPLAIN This query answers me *instantly* after hitting r