Re: How Postgresql Compares For Query And Load Operations

On Sat, 21 Jul 2001, Sean Chittenden wrote:

> > > I thought it was worth trying a different query as well :
> > >
> > > SELECT count(*) FROM fact0
> > >
> > > DB Elapsed Cpu
> > > Postgres 1m5s 32s
> > > Db2 23s 15s
> > > Oracle 37s 11s
>
> This may be an Oracle DBA myth, but I was told by my ORA DBA
> that it should be "SELECT count(1) FROM fact0" and not count(*). For
> some reason it was thought that count(1) would run faster, but I can't
> confirm or deny this. Does this make a difference in the benchmark?
> -sc

Actually, your oracle DBA was smoking crack. The real query is:

SELECT COUNT(rowid) FROM fact0;

RowID is a specially indexed field that Oracle uses to go DIRECTLY to a
record through the datafile->tablespace->cluster->row, hence circumvents
both indexes and the table itself.

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