Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: How does Oracle set the High Water Mark?

Re: How does Oracle set the High Water Mark?

From: Tim Gorman <tim_at_sagelogix.com>
Date: Wed, 10 Mar 2004 07:13:06 -0700
Message-ID: <BC747082.11409%tim@sagelogix.com>


Used to be controlled by a hidden parameter named:

PARAMETER                               DESCRIPTION          DFLT
--------------------------------------- -------------------- -----
_bump_highwater_mark_count          = 0 how many blocks      TRUE
                                        should we allocate
                                        per free list on
                                        advancing HW

And it used to default to 5. But, on my 9.2.0.1 database, it doesn't appear to have a default value at all. If it is being calculated internally, then on your database it seems to be 13, perhaps?

on 3/10/04 6:56 AM, Feighery Raymond at Raymond.Feighery_at_churchill.com wrote:

> Oracle 9.2.0.4 Solaris 8
>
> How does Oracle set the HWM? In the example below, I create a table and
> insert one row. I would expect only one block to be used, instead Oracle
> seems to have pushed the HWM up to 13 blocks. I can imagine that this might
> be done to "pre-mark" rows as used during bulk inserts, but how does Oracle
> decide where to set the HWM?
>
> SQL> select * from dba_tablespaces where tablespace_name = 'EXAMPLE';
> TABLESPACE_NAME BLOCK_SIZE INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS
> ------------------------------ ---------- -------------- -----------
> -----------
> MAX_EXTENTS PCT_INCREASE MIN_EXTLEN STATUS CONTENTS LOGGING FOR EXTENT_MAN
> ----------- ------------ ---------- --------- --------- --------- ---
> ----------
> ALLOCATIO PLU SEGMEN DEF_TAB_
> --------- --- ------ --------
> EXAMPLE 4096 65536 1
> 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL
> SYSTEM NO AUTO DISABLED
>
> SQL> create table t (col1 number(1));
> Table created.
> SQL> analyze table t compute statistics;
> Table analyzed.
> SQL> insert into t values(1);
> 1 row created.
> SQL> commit;
> Commit complete.
> SQL> select blocks, empty_blocks from user_tables where table_name = 'T';
> BLOCKS EMPTY_BLOCKS
> ---------- ------------
> 0 16
> SQL> analyze table t compute statistics;
> Table analyzed.
> SQL> select blocks, empty_blocks from user_tables where table_name = 'T';
> BLOCKS EMPTY_BLOCKS
> ---------- ------------
> 13 3
>
> ___________________________________________________________________________
>
>
> This email and any attached to it are confidential and intended only for the
> individual or entity to which it is addressed. If you are not the intended
> recipient, please let us know by telephoning or emailing the sender. You
> should also delete the email and any attachment from your systems and should
> not copy the email or any attachment or disclose their content to any other
> person or entity. The views expressed here are not necessarily those of
> Churchill Insurance Group plc or its affiliates or subsidiaries. Thank you.
>
> Churchill Insurance Group plc. Company Registration Number - 2280426.
> England.
>
> Registered Office: Churchill Court, Westmoreland Road, Bromley, Kent BR1
> 1DP.
>
>
> ----------------------------------------------------------------
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> ----------------------------------------------------------------
> To unsubscribe send email to: oracle-l-request_at_freelists.org
> put 'unsubscribe' in the subject line.
> --
> Archives are at http://www.freelists.org/archives/oracle-l/
> FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
> -----------------------------------------------------------------



Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
Received on Wed Mar 10 2004 - 08:18:14 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US