Re: [HACKERS] Much Ado About COUNT(*)

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This is probably stupid for some reason, but why not use a 64-bit
integer to track the number of records in the table? Increment when
adding records, decrement when deleting them... then COUNT(*) could
just return that in cases where a query is known to be looking at all
of the records?

On Jan 14, 2005, at 12:04 PM, Wes wrote:

> On 1/13/05 6:44 PM, "Greg Stark" <gsstark@mit.edu> wrote:
>
>> That's simply false. Oracle does indeed have to count the records one
>> by one.
>>
>> It doesn't have to read and ignore the dead records since they're in a
>> separate place (but on the other hand it sometimes have to go read
>> that
>> separate place when it sees records that were committed after your
>> transaction).
>>
>> It can also do index-only scans, which often helps, but it's still not
>> instantaneous.
>
> Ok, I stand corrected - I was given some wrong information.  However,
> my
> experience has been that count(*) on Oracle is a whole lot faster than
> PostgreSQL - what appeared instantaneous on Oracle took some time on
> PostgreSQL.  That was one of the first things I noticed when moving a
> database application to PostgreSQL.  I've since disposed of the Oracle
> database, so can't go back and retest.
>
> Wes
>
>
>
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>
- -----------------------------------------------------------
Frank D. Engel, Jr.  <fde101@fjrhome.net>

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