Two reasons:
- if you go into extent map blocks then you will
suffer an overhead of at least 1 billionth of a
percent :-)
- more seriously, its generally easier to pick up a
"rogue" table if its run into thousands of extents and
you had not intended it to. Its not a performance
problem per se, but its indicative that its a segment
thats doing something that was unforseen in the design
phase..
hth
connor
- [EMAIL PROTECTED] wrote: > I just read a .pdf by a
couple of people at oracle
> called Stop Fragmenting and start living where it
> says not worry about the number of extents in a
> tablespace. However in the administrators doc it
> says the following:
>
> Estimate Table Size and Set Storage Parameters
> Estimating the sizes of tables before creating them
> is useful for the following reasons:
>
> You can use the combined estimated size of tables,
> along with estimates for indexes, rollback segments,
> and redo log files, to determine the amount of disk
> space that is required to hold an intended database.
> From these estimates, you can make correct hardware
> purchases and other decisions.
>
> You can use the estimated size of an individual
> table to better manage the disk space that the table
> will use. When a table is created, you can set
> appropriate storage parameters and improve I/O
> performance of applications that use the table. For
> example, assume that you estimate the maximum size
> of a table before creating it. If you then set the
> storage parameters when you create the table, fewer
> extents will be allocated for the table's data
> segment, and all of the table's data will be stored
> in a relatively contiguous section of disk space.
> This decreases the time necessary for disk I/O
> operations involving this table.
>
> this is at the following link:
>
>
http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76956/tables.htm#208
>
> am I reading this wrong or is Oracle stating that
> you should have less extents in a table? I know
> several people on here have posted that the number
> of extents used by an object is almost irrelevant.
>
> --
> Please see the official ORACLE-L FAQ:
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> --
> Author: <[EMAIL PROTECTED]
> INET: [EMAIL PROTECTED]
>
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Received on Fri Jun 20 2003 - 11:25:48 CDT
