Skip to Main Content
IBM Data and AI Ideas Portal for Customers


This portal is to open public enhancement requests against products and services offered by the IBM Data & AI organization. To view all of your ideas submitted to IBM, create and manage groups of Ideas, or create an idea explicitly set to be either visible by all (public) or visible only to you and IBM (private), use the IBM Unified Ideas Portal (https://ideas.ibm.com).


Shape the future of IBM!

We invite you to shape the future of IBM, including product roadmaps, by submitting ideas that matter to you the most. Here's how it works:


Search existing ideas

Start by searching and reviewing ideas and requests to enhance a product or service. Take a look at ideas others have posted, and add a comment, vote, or subscribe to updates on them if they matter to you. If you can't find what you are looking for,


Post your ideas

Post ideas and requests to enhance a product or service. Take a look at ideas others have posted and upvote them if they matter to you,

  1. Post an idea

  2. Upvote ideas that matter most to you

  3. Get feedback from the IBM team to refine your idea


Specific links you will want to bookmark for future use

Welcome to the IBM Ideas Portal (https://www.ibm.com/ideas) - Use this site to find out additional information and details about the IBM Ideas process and statuses.

IBM Unified Ideas Portal (https://ideas.ibm.com) - Use this site to view all of your ideas, create new ideas for any IBM product, or search for ideas across all of IBM.

ideasibm@us.ibm.com - Use this email to suggest enhancements to the Ideas process or request help from IBM for submitting your Ideas.

IBM Data & AI Roadmaps (http://ibm.biz/Data-and-AI-Roadmaps) - Use this site to view roadmaps for Data & AI products.

IBM Employees should enter Ideas at https://hybridcloudunit-internal.ideas.aha.io/


Status Not under consideration
Workspace Db2
Created by Guest
Created on Feb 5, 2018

Union all View (or common table expression of a UNION ALL) lead to HSJOIN

Case #0000086

Worked with developer and provided following explanation:
When there is a join between a UNION ALL view (or a common table expression of a UNION ALL) to another input (let's named it Z), to be able to utilize index access on the tables under the UNION ALL from the join columns (in this case, ACNT_ID from the tables SMB.MBA_TRDG_YEAR_xxxx), it is required that the input Z and the join predicates are rewritten to join with the tables directly. The most common use cases is when Z is a single table. In this reported query, Z is derived from a GROUP BY operation, hence it is not rewritten to join with the tables under UNION ALL view directly. Consequently, the join columns are not used to probe into the indexes, although index access method is chosen.
There are reasons Db2 does not rewrite when Z is a GROUP BY or any other operations. One is because those operations are need to re-computed for the join of each table under the UNION ALL, which could end up more costly than the original form.