Re: Server hang after SELECT command
1999-05-18 09:56:05
Subject: |
Re: Server hang after SELECT command |
From: |
Bill Colwell <bcolwell AT DRAPER DOT COM> |
Date: |
Tue, 18 May 1999 09:56:05 -0400 |
I have given up on doing joins in select statements. I have had to
cancel the server a number of times in the past when I did
try a join. My server is at 3.1.2.14 on os/390 1.3. I have also found
that the volumeusage table is a real dog even without a join.
If I really need a
report like that I do simple selects and load the data into a real dbms like
db2 which has well tuned code to do a join and where I can improve
the speed by creating my own indexes.
Lets remember here that ADSM is NOT a general purpose dbms.
I won't press IBM to improve
the select performance. I want continual improvements in backup & restore
times. The select features are marginal to the product.
--
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Bill Colwell
Bill Colwell
C. S. Draper Lab
Cambridge, Ma.
bcolwell AT draper DOT com
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In <H00013210260cc55@MHS>, on 05/17/99
In <H00013210260cc55@MHS>, on 05/17/99
at 04:39 PM, Thomas Denier <Thomas.Denier AT MAIL.TJU DOT EDU> said:
>My site has an ADSM server running under MVS at service level 3.1.2.20. I have
>been trying to understand the more arcane capabilities of the select command.
>I executed the following command earlier today:
>select volume_name, devclass from volumes, stgpools where
> volumes.stgpool_name=stgpools.stgpool_name
>The server hung. The administrative client session I was using became totally
>unresponsive. When I attempted to start another administrative client session
>the password prompt never appeared. When I issued a command using the MVS
>modify command the ADSM command was echoed to the console but nothing else
>ever happened. An MVS stop command failed to bring down the server. I finally
>resorted to the MVS cancel command. I was able to bring up the server again
>with no sign of unusual behavior. It may be significant that there was a 'move
>data' process running when the hang occured.
>I am now decidedly nervous about running complex select commands. Does anyone
>have any information on the dividing line between select commands that are
>safe and select commands that cause hang conditions?
>This is only one of several annoying bugs I have run into lately. Why is there
>so much sloppy workmanship in the current ADSM code?
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