How does a select Query Works?

mailsaurabh.tripathi · New User Joined: 22 May 2008 Posts: 56 Location: hyderabad

Hi

I need to decide that do we need commit's in select queries?
I belive with commit, the page is returned to the disk. As in case of select, the data will not change, is commit required? Also we if don't do a commit, what will happen to the rows fetchwd into the bufferpool? How does DB2 clears them from BP?
To undertand these question, i think it's necesary to understand how does a select works.
Please help me with these questions.

Regards
Saurabh Tripathi

dbzTHEdinosauer · Posted: Tue Aug 24, 2010 8:01 pm

Read thru this and if you have any questions,
come back and I will give you more links.

mailsaurabh.tripathi · New User Joined: 22 May 2008 Posts: 56 Location: hyderabad

Thnx for the wonderful link.
Please explain, how does a select query works internally, i.e the steps followed by DB2 to process a select query.

dbzTHEdinosauer · Posted: Tue Aug 24, 2010 9:12 pm

if you do not want to peruse the manuals (link top of the page)
you can run EXPLAINs, which will tell you exactly how each query runs.