MySQL Bugs: #97927: Query Execution Plan Hash

Bug #97927	Query Execution Plan Hash
Submitted:	9 Dec 2019 13:05	Modified:	9 Dec 2019 15:29
Reporter:	Oli Sennhauser	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Optimizer	Severity:	S4 (Feature request)
Version:	any	OS:	Any (n.a.)
Assigned to:		CPU Architecture:	Any (n.a.)
Tags:	execution plan, explain, hash

Description:
On an Oracle conference I was following some talks about the Oracle Optimizer.

They where talking about changing Execution Plans for the same queries and that they can verify the executions plan changes via a Hash over the QEP.

Would be nice to have something similar in the P_S.

How to repeat:
n.a.

Suggested fix:
Would be nice to have something similar in the P_S.

Hi Oli,

Thank you for this feature request.

Before deciding on its validity, could you please explain in more detail how would you like to see this new feature functioning exactly.

Providing more description on query execution hash on P_S, would be very welcome.

Hi Sinisa

A nice example here (just search for "hash"):
https://blogs.oracle.com/optimizer/whats-changed-between-my-new-query-plan-and-the-old-one

A very short and concise explanation here: 
https://docs.oracle.com/cd/B19306_01/server.102/b14237/statviews_3179.htm#REFRN23443

Numerical representation of the SQL plan for the cursor. Comparing one PLAN_HASH_VALUE to another easily identifies whether or not two plans are the same (rather than comparing the two plans line by line).

More general stuff here:
https://docs.oracle.com/en/database/oracle/oracle-database/19/tgsql/generating-and-display...

Best Regards,
Oli

Hi Oli,

Thank you for the explanation.

Verified as a feature request.