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Help about understand values retrieved by Tom Kyte script for my LOB segment

trajonJan 17 2015 — edited Jan 23 2015

I have LOB segment. When I use Tom Kyte script show_space

(https://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:14339684180676) a have this output:

Unformatted Blocks .....................             107

FS1 Blocks (0-25)  .....................               0

FS2 Blocks (25-50) .....................               0

FS3 Blocks (50-75) .....................               0

FS4 Blocks (75-100).....................               0

Full Blocks        .....................         859,438

Total Blocks............................       1,746,304

Total Bytes.............................  14,305,722,368

Total MBytes............................          13,643

Unused Blocks...........................               0

Unused Bytes............................               0

Last Used Ext FileId....................               5

Last Used Ext BlockId...................       1,261,056

Last Used Block.........................             128

I have only Full Blocks = 859,438, but Total Blocks = 1,746,304 why so?
This post has been answered by Jonathan Lewis on Jan 17 2015
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Jonathan Lewis
Answer

It looks like you chunk size is 16KB - Oracle seems to look only at the chunk headers in this code; so you would expect the raw segment's number of blocks to be twice the space "blocks" that this report produces if you're running an 8KB block size and a 16KB chunk size.

Regards

Jonathan Lewis

Marked as Answer by trajon · Sep 27 2020
trajon

Thank you very much. I truly have CHUNK 16384. Your answer helped me very much.

Jonathan Lewis 
trajon wrote:




Thank you very much. I truly have CHUNK 16384. Your answer helped me very much.

My pleasure; thanks for the comment.

I've also written a short blog note about this example: https://jonathanlewis.wordpress.com/2015/01/21/lob-space/

Regards

Jonathan Lewis

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