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Are the extension pages of a table placed on the same dbspace as the regular table pages?

VolkerBarth
Contributor
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3,319

I guess the answer is "yes" but are not sure how to check that...

Running 16.0.0.2704, I have added a dbspace (*) to store blob data on that separate dbspace. Now it looks like the system dbspace has unexpectedly grown, too.

However, according to SYSTAB and SYSIDX, the freshly created tables and their indexes are stored on the dbspace, as desired.

Because most rows are stored in extension pages, I'm unsure whether they are stored in the dbspace, too.

Is there a system procedure to check that?


(*) I usually do not use separate dbspaces but in that case, it's quite likely the blob data will be purged lateron, and I do not want to have the main database file grown too much.

Accepted Solutions (1)

Accepted Solutions (1)

johnsmirnios
Advisor
Advisor

The extension pages are stored in the same dbspace as the other table pages.

Are you updating or deleting blobs? If so, perhaps the increased file size you are seeing is the checkpoint log. The checkpoint log at the end of the system dbspace is used for saving images from all dbspaces. You can use db_property('CheckpointLogSize') to find how many pages in the system dbpsace file are being used for the checkpoint log.

VolkerBarth
Contributor
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Ah yes, the checkpoint log has grown that much... - although I have just used LOAD TABLE to insert these blobs, so there should not have been any blob updates...

johnsmirnios
Advisor
Advisor

Insertion doesn't usually generate many checkpoint log pages since newly allocated pages don't get a preimage stored in the checkpoint log (there is no preimage for a newly allocated page). That's why I asked if you were updating or deleting. Index pages will get modified for inserts though.

VolkerBarth
Contributor
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Thanks again, John – Then I guess this is due to modified index pages because I created several indixes before loading the data, and loading will have led to modified index pages. So I'm thinking about delaying the index creation after the initial loading...

Answers (0)