Bug #20889 Documentation: Misunderstandable example in 7.2.6. Index Merge Optimization
Submitted: 6 Jul 2006 14:09 Modified: 6 Jul 2006 17:55
Reporter: Sebastian Nohn Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.0 OS:Irrelevant
Assigned to: Paul Dubois CPU Architecture:Any
Triage: D4 (Minor)

[6 Jul 2006 14:09] Sebastian Nohn
Description:
In 7.2.6. Index Merge Optimization this example is used:

SELECT * FROM t1 FORCE INDEX(goodkey1,goodkey2)
  WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30;

SELECT * FROM t1 IGNORE INDEX(badkey)
  WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30;

that may implicate that index_key_name == table_name, which is of course not.

The example on 7.2.15. How to Avoid Table Scans is much clearer here:

SELECT * FROM t1, t2 FORCE INDEX (index_for_column)
  WHERE t1.col_name=t2.col_name;

How to repeat:
.

Suggested fix:
Make example on FORCE INDEX in 7.2.6. Index Merge Optimization clearer
[6 Jul 2006 17:50] Valeriy Kravchuk
Thank you for a reasonable documentation request. You meant "index_key_name == column_name", I hope...
[6 Jul 2006 17:55] Paul Dubois
Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant product(s).