When to perform RUNSTATS in DB2 is the prime question in SQL interviews. Here are ideas and examples for you to tell correct answer in your next interview.
You may also like Array vs List in Python.
This is a question for developers while working on projects and when they give interviews. Runstats is a utility that collects statistics and sends these to the optimizer for the right decision.
When to Run Runstats in DB2
You need to run this utility during the below scenarios.
- When a table is loaded
- When an index is created
- When a tablespace is reorganized
- When there have been extensive updates, deletions, or insertions in a tablespace
- After the recovery of a tablespace to a prior point in time
How Optimizer Decision Affects When You Not Collect Statistics
- The optimizer may not take the right decision for multi-joint tables query
- The optimizer may choose the wrong choice of index, which in turn affects performance
- When a column designed to have default values, you need to run the RUNSTATS utility for frequency value statistics help in better decision
How to Know When to Execute Runstats
- You need to refer to SYSIBM.SYSCOLDIST catalog table about the running of Runstats utility is needed or not. The IBM Data Studio tool will also show those statistics.
- DB2 gets the frequency value of statistics when Runstats utility is executed.
Keep Reading
DB2: How to Understand B-Tree Structure of Index
Here is the top B-Tree index mechanism that followed in DB2. It is a helpful explanation for DB2 developers.
3 Top Steps to Transform Bigdata to Useful Information
Here are three top processing steps to convert Bigdata to useful information.
AWS Simple Queue Service: Here is Default Retention Period
Amazon SQS’s powerful feature is you can use this for communication between distributed components. Here is its architecture and default retention period.
You must be logged in to post a comment.