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RE: count(*)

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Thu, 19 Sep 2002 13:03:39 -0800
Message-ID: <F001.004D44E8.20020919130339@fatcity.com>

Sent: Thursday, September 19, 2002 2:48 PM To: 'ORACLE-L_at_fatcity.com'

Rishi - I've encountered this as well. I think the problem is the fact that you are pounding millions of rows into the table. When you ask for a count, Oracle won't give you an approximate answer, but insists on giving you a precise answer as of the moment you hit return. You are right, your query can actually slow performance. No, to my knowledge Oracle doesn't maintain a record of the number of rows in the table, my guess being that could become a performance bottleneck.

   My recommendation would be to ask very precisely what is to be achieved with the count. As you noticed, the count will lag reality by quite awhile. Perhaps the application could maintain the count. I have quite a few batch programs that will display a running counter. If only an approximate count is needed, there may be an alternate method, like looking at how many segments are used and calculating. Just some thoughts.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com <mailto:dwilliams_at_lifetouch.com>

-----Original Message-----
[mailto:Rishi.Jain_at_VerizonWireless.com]
Sent: Thursday, September 19, 2002 1:28 PM To: Multiple recipients of list ORACLE-L

Hi Gurus,

In one of our insert intensive application we are inserting around 3-4 million rows / hour. Also this app needs to do a count(*) of the tables every 10 minutes for verifying some application based logic. This is really killing us and it takes a lot of time.

Can you please guide me to a direction ( built in functions or something similar).

Actually this app is being ported from Informix. Informix can somehow keep a trak of the count(*) of a table in its header somewhere.

And yes I have tries count(1) , count(indexed_column) etc.

Thanks In Advance.

R.h
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  INET: Rishi.Jain_at_VerizonWireless.com

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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM
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