RE: rebuild indexes
- From: "Uzzell, Stephan" <SUzzell@xxxxxxxxxx>
- To: "'JBECKSTROM@xxxxxxxxx'" <JBECKSTROM@xxxxxxxxx>
- Date: Fri, 18 Apr 2014 18:46:16 +0000
Well, this could be one of the valid use cases for a shrink / move: if the
table is a queue type table (either AQ or homegrown), it may currently have
only 14 rows or some such. But it there ever was a time when the dequeue
stopped or failed, the table could have grown ridiculously.
If there’s no appropriate index (or none whatsoever, perhaps, because a queue
table should never have more than a handful of rows) then Oracle will have to
read up to the HWM, and if that got pushed out pretty far, that could well
cause a performance issue.
Stephan Uzzell
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Jeffrey Beckstrom
Sent: Friday, 18 April, 2014 14:15
Cc: oracle-l (oracle-l@xxxxxxxxxxxxx)
Subject: Re: rebuild indexes
How many blocks is the table occupying? For the number of rows you list, it
can't be more than a block or two and would probably save little.
>>> Andy Gmail <andrew.kerber@xxxxxxxxx<mailto:andrew.kerber@xxxxxxxxx>>
>>> 4/18/14 2:05 PM >>>
Yes. Just run alter table move tablespace whatever then rebuild the indexes.
That will accomplish what you need.
Sent from my iPhone
On Apr 18, 2014, at 12:37 PM, "Zelli, Brian"
<Brian.Zelli@xxxxxxxxxxxxxxx<mailto:Brian.Zelli@xxxxxxxxxxxxxxx>> wrote:
One table has 14 rows and the other has 26. They say it is causing performance
issues……
Brian
From: Andrew Kerber [mailto:andrew.kerber@xxxxxxxxx]
Sent: Friday, April 18, 2014 1:37 PM
To: Zelli, Brian
Cc: oracle-l (oracle-l@xxxxxxxxxxxxx<mailto:oracle-l@xxxxxxxxxxxxx>)
Subject: Re: rebuild indexes
How big is the table? He probably wants you to shrink it by eliminating unused
blocks. The simplest way to do that is by an alter table move command followed
by alter index rebuild.
Sent from my iPad
On Apr 18, 2014, at 12:26 PM, "Zelli, Brian"
<Brian.Zelli@xxxxxxxxxxxxxxx<mailto:Brian.Zelli@xxxxxxxxxxxxxxx>> wrote:
A vendor wants me to shrink a table. I’ve never shrunk one in oracle. Does
that delete the data out of them?
And then wants me to rebuild the associated indexes. Won’t they be empty after
you shrink them?
Brian
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