> Hi everyone,
>
> What typical/max database I/O throughputs are people getting for simple
> selects of datasets cached in memory but not explicitly clustered?
> 100KB/sec? 1MB/sec? 10MB/sec? (assuming << 8KB rows).
I see transfer rates that match the I/O speed of the disk.
>
> Does a "select count(*) from tablename where ..." actually retrieve all
> columns from all the selected rows or does it only count the rows?
Yes, it reads all rows.
>
> That is to say:
> would/should select count(*) be slower than select
> count(averysmallcolumnmaybeboolean)
Same speed.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 853-3000
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