Portal | Manuals | References | Downloads | Info | Programs | JCLs | Master the Mainframes
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Usergroups Profile Log in to check your private messages Log in
 

 

Optimum access path

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> DB2
View previous topic :: :: View next topic  
Author Message
harikrishnanrajeev

EXPERT


Joined: 28 Jan 2004
Posts: 37
Location: Trivandrum

PostPosted: Fri Mar 05, 2004 11:57 pm    Post subject: Optimum access path
Reply with quote

Hello all,

I have a doubt in Bind. During bind i read that an
Quote:
optimum access path
is created and that an optimizer is responsible for this. I would like to ask what actually is access path .

Thanks and regards,

Hari.
Back to top
View user's profile Send private message

anuradha

Active User


Joined: 06 Jan 2004
Posts: 247
Location: Hyderabad

PostPosted: Tue Mar 09, 2004 5:25 pm    Post subject: optimal access path
Reply with quote

Hi Hari,

What u read is correct.Determining the method of access or access path(watever we call)is an automatic function of DB2. This function is performed during the bind process for static SQL or during execution time for dynamic SQL.

Access path is nothing but the order in which records in a database file are processed.Access paths reduces the system overhead.Access path selection criteria is based on the statistical information which is stored in db2 catalog.These catalog statistics are updated by execution of the RUNSTATS utility. DB2's determination of the most efficient access paths is dependent on the accurate and realistic statistics of this catalog.Optimal access path selection is important to resource utilization.Access path selection may include the use of RUNSTATS, rebinding, and EXPLAIN.

If the runstats is incomplete and doesn't reflect the current state of data there are more chances to select a very bad access path instead of good one.So we should see that always db2 catalog has current statistics.

Hope this helps.others can add

THANKS AND REGARDS
ANU
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> DB2 All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
No new posts find RACF group for access to spooled... jzhardy JCL & VSAM 1 Mon May 08, 2017 11:46 am
No new posts IMS DC screen Access sivasaras IMS DB/DC 3 Fri Nov 18, 2016 6:38 pm
No new posts Access SQLCA fields inside a stored p... gangapd DB2 6 Thu Oct 27, 2016 10:20 am
No new posts RACF profile access vasanthz All Other Mainframe Topics 11 Fri Sep 23, 2016 5:51 am
No new posts How to perform Digest Access Authenti... vasanthz All Other Mainframe Topics 0 Tue Mar 15, 2016 4:47 pm


Facebook
Back to Top
 
Mainframe Wiki | Forum Rules | Bookmarks | Subscriptions | FAQ | Tutorials | Contact Us