Re: OBJECT DESING

2002-04-20 Thread Don Granaman

For the radical approach - as espoused by Dave Ensor - PCTUSED=0 !!!  (If
this doesn't generate some serious discussion, I'll be amazed!)

This works quite well for tables where records are purged some set length of
time after insert.  The net result is that blocks are filled, then left
alone until purged when they (the vast majority at least) are completely
emptied and put back on the free list.  Blocks tend to be fully populated
and freelist activity is minimized.  Be aware that in some older versions of
Oracle, there is a bug that requires PCTUSED = 1 (blocks only move back to
the free list if used space  PCTUSED instead of = PCTUSED).  I do not know
offhand what version fixed this.

Dave Ensor's suggestion was to use this (almost) everywhere, but I'm not
really comfortable with it as a blanket policy.  It seems that tables with
deletes that are chronologically random would end up with a LOT of very
sparsely populated blocks.

The approach recommended below is to set it rather high to accomplish the
block density goal, but at the potential expense of high freelist activity.
Which approach is more appropriate depends on the nature of one's
insert/delete criteria.

Also, PCTFREE can be set extremely low (1,5,?) for some kinds of objects -
static tables, indexes with strictly inorder data (CREATE_DATE, SEQUENCE#,
etc.).

I agree with always setting PCTINCREASE =0

Don Granaman
[OraSaurus - Honk if you remember UFI !]

- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Thursday, April 18, 2002 8:08 AM


 Seema,

 PCTINCREASE - always 0.

 PCTFREE - for lookup (code) tables = 10 for others, I use 20.  My theory
is
 that lookup tables have little or no updates, so this value should be
small.
 If you have a high-update tables (columns that are updated a 8lot* after
the
 record was created, you may want a higher value here.

 PCTUSED - for lookup (code) tables = 90, for others, I use 80.  Again, for
 lookup tables with little or no updates, I fill the data blocks as high as
 possible.  For other tables, I currently use 80 as a starting point.

 You will get many opinions here - read the docs to determine what you
think
 is best for you.

 Hope this helps.

 Tom Mercadante
 Oracle Certified Professional

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Re: OBJECT DESING - Odd reason for bounce

2002-04-20 Thread Don Granaman

Perhaps OT, but funny.  I wasn't aware that the word random was offensive
to anyone.  I'll try to be more careful!
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Re: OBJECT DESING

2002-04-20 Thread Jared Still


Interesting, I hadn't previously heard that.

Makes sense though, indexes work that way by default.
And you can't change that behavior.

Using a combination of PCTFREE and PCTUSED that adds
up to 100 can lead to a lot of update activity on the free list.

Or at least I seem to recall that, I haven't actually experienced
it.  At least I dont' remember experiencing it.  Everyone was
a newbie at some point.  :)

Jared


On Saturday 20 April 2002 09:33, Don Granaman wrote:
 For the radical approach - as espoused by Dave Ensor - PCTUSED=0 !!!  (If
 this doesn't generate some serious discussion, I'll be amazed!)

 This works quite well for tables where records are purged some set length
 of time after insert.  The net result is that blocks are filled, then left
 alone until purged when they (the vast majority at least) are completely
 emptied and put back on the free list.  Blocks tend to be fully populated
 and freelist activity is minimized.  Be aware that in some older versions
 of Oracle, there is a bug that requires PCTUSED = 1 (blocks only move back
 to the free list if used space  PCTUSED instead of = PCTUSED).  I do not
 know offhand what version fixed this.

 Dave Ensor's suggestion was to use this (almost) everywhere, but I'm not
 really comfortable with it as a blanket policy.  It seems that tables with
 deletes that are chronologically random would end up with a LOT of very
 sparsely populated blocks.

 The approach recommended below is to set it rather high to accomplish the
 block density goal, but at the potential expense of high freelist activity.
 Which approach is more appropriate depends on the nature of one's
 insert/delete criteria.

 Also, PCTFREE can be set extremely low (1,5,?) for some kinds of objects -
 static tables, indexes with strictly inorder data (CREATE_DATE, SEQUENCE#,
 etc.).

 I agree with always setting PCTINCREASE =0

 Don Granaman
 [OraSaurus - Honk if you remember UFI !]

 - Original Message -
 To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
 Sent: Thursday, April 18, 2002 8:08 AM

  Seema,
 
  PCTINCREASE - always 0.
 
  PCTFREE - for lookup (code) tables = 10 for others, I use 20.  My theory

 is

  that lookup tables have little or no updates, so this value should be

 small.

  If you have a high-update tables (columns that are updated a 8lot* after

 the

  record was created, you may want a higher value here.
 
  PCTUSED - for lookup (code) tables = 90, for others, I use 80.  Again,
  for lookup tables with little or no updates, I fill the data blocks as
  high as possible.  For other tables, I currently use 80 as a starting
  point.
 
  You will get many opinions here - read the docs to determine what you

 think

  is best for you.
 
  Hope this helps.
 
  Tom Mercadante
  Oracle Certified Professional
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Jared Still
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RE: OBJECT DESING

2002-04-18 Thread Mercadante, Thomas F

Seema,

PCTINCREASE - always 0.

PCTFREE - for lookup (code) tables = 10 for others, I use 20.  My theory is
that lookup tables have little or no updates, so this value should be small.
If you have a high-update tables (columns that are updated a 8lot* after the
record was created, you may want a higher value here.

PCTUSED - for lookup (code) tables = 90, for others, I use 80.  Again, for
lookup tables with little or no updates, I fill the data blocks as high as
possible.  For other tables, I currently use 80 as a starting point.  

You will get many opinions here - read the docs to determine what you think
is best for you.

Hope this helps.

Tom Mercadante
Oracle Certified Professional


-Original Message-
Sent: Wednesday, April 17, 2002 5:38 PM
To: Multiple recipients of list ORACLE-L


Hi
WHat is best practices for PCTFREE,PCTUSED AND PCT_INCREASE value at object 
level?
Thx
-seema




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OBJECT DESING

2002-04-17 Thread Seema Singh

Hi
WHat is best practices for PCTFREE,PCTUSED AND PCT_INCREASE value at object 
level?
Thx
-seema




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