Reasons for backup size decreasing

[danishgambit]

Afternoon 'talkers,

OE 10.2A on Red Hat.

We've got a database (8 kb blocksize), which we do a full backup of every evening. For information, the backup is done online, with the -com option. We've noticed that the most recent backup was about 17 blocks smaller than the previous backup. Given that there was no administration of the database between the backups - what possible reasons are there for this size reduction ?

Initial thought is deletion of records.

regards,

DG.

 

[TomBascom]

Deletion of records would certainly account for it.

 

[cj_brandt]

I thought probkup backed up blocks until the HWM of an area. HWM doesn't change with a record deletion. Does the count of blocks include the BI area ? If there was a large open transaction one day and it was gone the next, that might be it.

 

[TomBascom]

The -com option to probkup eliminates empty space (it does not, however, do "zip" style compression, it just skips empty space). So if you delete records the backup can be smaller.

 

[danishgambit]

Morning,

thanks for the information. Happy with the explanations posted - I wouldn't have expected the HWM to reflect deleted records, but if the -com option is skipping empty space below the HWM that explains why it could be smaller. Solved.

Regards,

DG