afraid to admit...

dr_te_z · #1 (**permalink**) 03-24-11, 02:35

I have db2 certificates

so I'm suppose to know it all..... yeah right!

Currently I am analyzing "db2pd tcbstats" output and here (db2pd to monitor table access) I read about "RID Scans".... Ehhh what ís a RID scan? Must have missed it or forgot all about it.
I understand it spoils the significance of the "scans" column in my db2pd report, but what else does it do?

sathyaram_s · #2 (**permalink**) 03-24-11, 02:53

Understanding DB2 Query Access Plans :: Chapter 6. The DB2 Optimizer :: Advanced dba certification guide and reference :: Misc :: eTutorials.org

dr_te_z · #3 (**permalink**) 03-24-11, 04:45

Thanks. 'Super Moderator' really means something

.
So a RID scan a.k.a. RIDSCN is good and only indicates that the prefetching is taking place.
The "scans" column on my db2pd report is bad because it does not contain any valueable information because bad tablescans and good ridscans are mixed.

sathyaram_s · #4 (**permalink**) 03-24-11, 13:36

Quote:

Originally Posted by dr_te_z

Thanks. 'Super Moderator' really means something

.

yeh, does mean something! I can delete threads and ban users that I don't like

Quote:

Originally Posted by dr_te_z

So a RID scan a.k.a. RIDSCN is good and only indicates that the prefetching is taking place.
The "scans" column on my db2pd report is bad because it does not contain any valueable information because bad tablescans and good ridscans are mixed.

RIDSCAN is better than a tablescan, but not necessarily a good thing.

Full index scans often result in RIDSCANs. Thoguh full index scans are better than full tablescans, they are not good.

There may be scope for reindexing or rewriting queries.

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