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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Tablespace layout
Lisa,
I have a copy of the paper you refer to and have read it a couple of times. We've gone over this issue many times in our team but our other two DBAs remain unconvinced. Perhaps I need to actually give them a copy of the paper.
As I said, the crux of the issue is whether we should only have one extent
size per tablespace or allow different extent sizes per tablespace, as long
as they are all multiples of each other. Over time, we've gotten so that
we're
in the later situation and it's getting unmanageable. However, I just
can't
convince these two and they keep changing the extent sizes in the
tablespaces
so there are more and more different sizes. I guess I'm looking for fuel
to convince them with, if there is any.
As for the partitions, I'm leaning towards putting the fact table that we
will be dropping
old partitions off of into a single tablespace per partition. The other
partitioned tables,
I'm thinking about leaving in the regular tablespaces where they are
currently located.
They are currently alternated between data01 and data02 as you said.
Thanks for your reply,
Cherie
"Koivu, Lisa"
<lisa.koivu_at_efair To: "'ORACLE-L_at_fatcity.com'"
<ORACLE-L_at_fatcity.com>,
field.com> "'cherie_machler_at_gelco.com'"
<cherie_machler_at_gelco.com>
cc:
08/28/01 03:05 PM Subject: RE: Tablespace layout
Well Satar you didn't even read Cherie's email.
Way back before I took that db to the tablespace layout you refer to (straight out of HOw to Stop Defragmenting and Start Living white paper) I had created a separate tablespace for each partition. It was an awful pain back then and the number of tablespaces I had was ridiculous. I can see your point with mttr and keeping your tablespaces fairly small in comparison to what it's become. I guess it's a tradeoff with pros and cons either way.
However, I suggest you take that paper (above) and throw it their faces. I disagree about different sized extents in the same tablespace vehemently. I think they should be uniform, period, for the same reason you state - if disk is so precious, then use it wisely !! Plus, when your partition starts looking for another 100MB extent, you are out of luck.
What's your feeling on partitioning? I think if you are dropping data monthly, use partitions wherever you can. That way you are more assured of reusing your disk - however, then you are looking at a different tablespace per partition.
I believe at one point I had 2-3 partitions in each tablespace, rotating them (part1 in ts1, part2 in ts2, part3 in ts1, part4 in ts2, etc.) Maybe that will provide the compromise in functionality, disk space management and recoverability you seek.
I do know your pain. Good Luck.
Lisa Koivu
Certified Monkey and DBA
Ft. Lauderdale, FL, USA
-----Original Message-----
From: Satar Naghshineh
[SMTP:Satar.Naghshineh_at_irvine.mellesgriot.com]
Sent: Tuesday, August 28, 2001 4:30 PM
To: Multiple recipients of list ORACLE-L
Subject: RE: Tablespace layout
Hi Cherie,
Just shove all your data on a RAID 5 (great for data Warehouses) and
forget about it. If that is not possible, then stick with what your
DBA team has stated about everything being ok as long as the extents
are multiples of one another.
Regards,
Satar Naghshineh
-----Original Message-----
From: Cherie_Machler_at_gelco.com [SMTP:Cherie_Machler_at_gelco.com]
Sent: Tuesday, August 28, 2001 7:27 PM
To: Multiple recipients of list ORACLE-L
Subject: Tablespace layout
I've been thinking a lot about our tablespace layout for our
data warehouse. Our warehouse is approaching 200Gig
and is almost out of space on disk. I'm getting another 75 Gig
this weekend and am trying to plan the best use for that 75Gig.
Our current data tablespace layout is that we have two tablespaces
for small, medium, and large data tables and the same for indexes.
So it's something like this:
SM_DATA01
SM_DATA02
MED_DATA01
MED_DATA02
LG_DATA01
LG_DATA02
SM_IDX01
SM_IDX02
MED_IDX01
MED_IDX02
LG_IDX01
LG_IDX02
I think that theoretically, all of the tables in each of the
tablespaces
were supposed to have the same sized extents when they were
originally created. However, over time, there are multiple sizes
of extents in the large and medium tablespaces. Even though we
show significant free space, it is fragmented and coalescing can
not put together enough contiguous space to reuse a lot of the
available
space.
Our largest tables are partitioned. However the partitions are not
split
out into separate tablespaces but go into the same medium and large
tablespaces as non-partitioned tables. Theoretically, I suppose that
this
is not a problem if, when partitions are dropped every month, the
resulting
space is reused 100%. I'm not sure if it is.
Here is my question. My DBA team members feel that it's fine to have
tables with a variety of extent sizes in the same tablespace as long
as
they are all multiples of each other (50, 100, 400, 2000, etc.). My
concern
is that this setup is fine when the smaller tables need to extend but
when
the larger tables need to extend, they can't pull together enough
contiguous
space and I keep having to add more. I'd prefer to have only one
size of
extent in each tablespace and keep it very pure that way. Then I
know
every single extent can be reused. So I am considering increasing the
number of tablespaces so we have something more like this:
1kdata
10kdata
100kdata
1mdata
10mdata
100mdata
1000mdata
1kidx
10kidx
100kidx
1midx
10midx
100midx
1000midx
I would also probably split them out into at least two tablespaces for
each
level.
Maybe not for the smaller sizes, but for the larger sizes.
I have several issues I'm trying to keep in mind. One is the ease of
maintenance
for initial creation and ongoing upkeep. I don't want to have too
many
tablespaces
if I don't need to. Another issue is mean time to recover. If we
lose a
single tablespace,
I'd prefer to have to recover fewer files. The maximum file size we
are
using is 2Gig.
We need to keep our recovery time under four hours total.
Probably the biggest issue I'm facing now is the sheer size of the
large
tablespaces.
They are so big and bulky that it's almost impossible to reorg them or
even
just
clean them up. I think that if I had more smaller tablespaces, I
would
have more
options. This database is still at 8.0.4 and it's going to be a while
before it can be
upgraded so that limits my options for reorging as well. All cleanup
has
to be done
in a series short Sunday windows. I don't have the luxury of a tool
for
doing this
reorg so have to do it manually.
Another issue is partitions. We are dropping the old partitions on
the
main fact
table once a month. We are not currently planning on dropping any of
the
other partitions.
The tables have a variety of partition names and schemes. Some are
partitioned yearly,
monthly, quarterly, half-yearly. There is no consistency. I'm
debating
whether I should
split each partition out into it's own tablespace. That would be
almost a
hundred tablespaces.
Or just the table that we're dropping partitions on monthly. That
would
be about 50 tablespaces.
Or should I just leave them all in the same tablespaces as
non-partitioned
tables?
We are using Sun Solaris 2.6 on an E10K. We have EMC disk and
Veritas
file manager.
Using version 8.0.4 of Oracle, as I said. Using RMAN and Veritas for
backups.
Any feedback, ideas, suggestions, things to watch out for, think
about,
etc. would be greatly
appreciated. This is going to take a lot of time and effort to do
and I
don't want to get all the
work done and find out it doesn't work as well as I hoped and have to
redo
everything.
Thanks for your time,
Cherie Machler
Oracle DBA
Gelco Information Network
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INET: Cherie_Machler_at_gelco.com
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: INET: Cherie_Machler_at_gelco.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Wed Aug 29 2001 - 07:35:01 CDT
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