DB2 Ideas When to Perform RUNSTATS

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.

DB2: 5 Bold Ideas When to Execute Runstats

DB2: 5 Bold Ideas When to Execute Runstats
DB2: 5 Bold Ideas When to Execute Runstats

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.

  1. When a table is loaded
  2. When an index is created
  3. When a tablespace is reorganized
  4. When there have been extensive updates, deletions, or insertions in a tablespace
  5. After the recovery of a tablespace to a prior point in time

How Optimizer Decision Affects When You Not Collect Statistics

  1. The optimizer may not take the right decision for multi-joint tables query
  2. The optimizer may choose the wrong choice of index, which in turn affects performance
  3. 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.

Keep Reading

SQL Query: How to Use LOCATE and Substring Correctly

Here are SQL queries to use the SUBSTRING function along with LOCATE function. LOCATE gives position, and SUBSTRING uses that for the start position.

Python Logic to use tell() and seek()

In Python, both tell and seek functions help you get the data from a file. How to use these explained on how to use in your current project.

Author: Srini

Experienced software developer. Skills in Development, Coding, Testing and Debugging. Good Data analytic skills (Data Warehousing and BI). Also skills in Mainframe.