Oracle-L: Re: PCT_USED/PCT_FREE : Storage of 32mb images

From: <Jared.Still_at_radisys.com>
Date: Wed, 06 Mar 2002 14:48:29 -0800
Message-ID: <F001.00421650.20020306144829@fatcity.com>

Darren,

Are these 4 images in separate tables?

Why an extent size of 32 meg?

Jared

"Browett, Darren" <dbrowett_at_city.coquitlam.bc.ca> Sent by: root_at_fatcity.com
03/06/02 09:53 AM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        PCT_USED/PCT_FREE : Storage of 32mb images

I am in the process of storing 32Mb image files into a 8.1.7 database, I have set
pct_free to 0, but I left pct_used at 90 and the tablespace is locally managed with a
uniform extent of 32Mb. The database has a db_block_size of 8k. I am considering moving it
to 16k, as opposed to 32k, as it has a mix of smaller files ( > 8k, < 7Mb) and then the larger tables ( 32 Mb).

When I loaded 4 images (to create one image), and analyzed the tables, I received the following output.

Size (numrow*avg_row_len)                = 115,437,005 
Bytes (Segments)                                 = 167,772,160 
Blocks                                                           = 20,480  
 
Extents                                                          = 5

As you can see, I am wasting 50Mbs of space for 4 images. I realize that if
I add another image to the larger
one, I most likely only waste 18 Mbs.

I have figured out that this wastage is due to the pct_used parameter. After re-re-re-reading the documents,
I should have set the pct_used higher then 90.

Question : Should I set pct_used to 100 or 99 ?

Once these images are loaded,the tablespace will be set to READONLY. No updates will occur.

Thanks

Darren

Darren Browett P.Eng                             This message
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