Possible Causes:
- HW Problem
- It's doing a Full Table Scan, and High Water Mark increase since yesterday
- New Stats and Yesterday did a Fast Full Index Scan in PK and today it's doing a FTS
...
And so on...
-----Original Message-----
From: George
[mailto:oracledba-ezmlmshield-x79283059.[Email Address Removed] zyDBA.com]
Sent: terça-feira, 31 de Maio de 2005 12:28
To: LazyDBA Discussion
Subject: RE: Select Count(*) very fast yesterday but
its slow today
Hi
The Better answer is that ... Create a trace file
using tkprof and check what would be the problem.....
George
-----Original Message-----
From: Amar Kumar Padhi
[mailto:oracledba-ezmlmshield-x10436370.[Email
address protected]
Sent: Tuesday, May 31, 2005 4:39 PM
To: LazyDBA Discussion
Subject: RE: Select Count(*) very fast yesterday but
its slow today
You have it right. In addition, one I could think of
is that there is something heavy running on the
server that has hogged up most of the resources. This
could be related to the memory available or the I/O
or the CPU, or even the network.
Thanks!
amar kumar padhi
-----Original Message-----
From: JAIMURUGAN Shanmuga Velayutham
[mailto:oracledba-ezmlmshield-x23705609.[Email
address protected]
Sent: 31 May 2005 14:18
To: LazyDBA Discussion
Subject: Select Count(*) very fast yesterday but its
slow today
Hi all,
This was the question recently I encountered in an
interview. I gave the answers below but that doesn't
seem to satisfy the interviewer.
QUESTION:-
SELECT COUNT (*) FROM TABLE_NAME:
The query ran fine and I got the output in less than
25 seconds. The next day I ran the same query and I
got the output after 15 minutes. What is the reason
for this? As a DBA what is that you will check immediately?
My Answer:-
1. Mass insert or mass delete would have happened in
the table, Statistics were not gathered after that
.So the performance has degraded. 2. Statistics would
have been deleted.
Are there any other reasons for the performance degradation?
Thanks in advance
JAIMURUGAN
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