Is the "Global Optimizer Statistics" section unreliable?

1

(repost)

Is the "Global Optimizer Statistics" section unreliable in a SQL Anywhere 17.0.10.5745 Graphical Plan With Statistics?

Should that section be ignored?

In particular, why does it say "Optimization goal All-rows" when all evidence, including the plan's own "Optimizer Statistics" section, says "optimization_goal First-row"?

This is critically important when it comes to debugging performance problems.

Here are some details...

=====
Graphical Plan
top SELECT node
Advanced Details tab
Global Optimizer Statistics
Optimization goal     All-rows     FALSE?

=====
top SELECT node
Details tab
Optimizer Statistics section
optimization_goal     First-row     TRUE?
ProductVersion        17.0.10.5745  

=====
reload.sql
SET OPTION "PUBLIC"."optimization_goal"='Response-time'

=====
Foxhound Display Schema 
SET OPTION PUBLIC.optimization_goal = 'Response-time'; -- different from default 'All-rows'

Note: For a TL;DR discussion of 'Response-time' === 'First-row' see this post: Database option optimization_goal value after upgrading database from version 9 to 17

asked 05 Apr '21, 11:33

Breck%20Carter's gravatar image

Breck Carter
32.5k●539●724●1050
accept rate: 20%

edited 12 Apr '22, 15:27

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question asked: 05 Apr '21, 11:33

question was seen: 535 times

last updated: 12 Apr '22, 15:27

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