RMAN unused block compression against TABLE drop vs TABLE with LOB column compression

Jan 25, 2017 7:31PM

Hi There,

I am just trying to understand RMAN unused block compression against TABLE with LOB column compression vs TABLE drop.

Consider LOB data for column 'DATA' in a table 'EMPLOYEES' under SCOTT schema.

- lob segment

SELECT SEGMENT_NAME FROM DBA_LOBS WHERE OWNER = 'SCOTT' AND TABLE_NAME = 'EMPLOYEES' AND COLUMN_NAME = 'DATA';

SEGMENT_NAME

--------------------------

LOBD_EMPLOYEES_DATA

CASE 1 : RMAN unused block compression against TABLE with LOB column compression

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SECTION 1 : PRE-LOB COMPRESS INFO

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1- Storage size of the LOBSEGMENT

SELECT SUM(BYTES)/1024/1024 "STORAGE_MB" FROM DBA_EXTENTS WHERE SEGMENT_NAME = 'LOBD_EMPLOYEES_DATA';

STORAGE_MB

----------

183420

2- Determine the size of the LOB DATA

Database Backup and Recovery (MOSC)