Bug #108574 The description of the Index Merge Union Access Algorithm is incorrect
Submitted: 22 Sep 7:24 Modified: 28 Sep 0:09
Reporter: Jinghua Lin Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.6, 5.7, 8.0 OS:Any
Assigned to: CPU Architecture:Any

[22 Sep 7:24] Jinghua Lin
Description:
The description of the Index Merge Union Access Algorithm in the documentation is that:

An N-part expression of this form, where the index has exactly N parts (that is, all index parts are covered):

key_part1 = const1 AND key_part2 = const2 ... AND key_partN = constN

It's same with the description of Index Merge Intersection Access Algorithm.

It should be modified as:

key_part1 = const1 OR key_part2 = const2 ... OR key_partN = constN

The correct description would be to replace "and" with "or".

How to repeat:
1. open https://dev.mysql.com/doc/refman/5.7/en/index-merge-optimization.html

2. Compare the contents of "Index Merge Union Access Algorithm" and "Index Merge Intersection Access Algorithm"
[22 Sep 7:41] MySQL Verification Team
Hello Jinghua Lin,

Thank you for the report and feedback.

regards,
Umesh
[28 Sep 0:09] Jon Stephens
Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly.