Skip to Main Content
  • Questions

  • performance tuning - sql slows down after gather stats

Breadcrumb

Question and Answer

Connor McDonald

Thanks for the question, krishna.

Asked: May 07, 2018 - 8:05 am UTC

Last updated: May 11, 2018 - 8:32 am UTC

Version: 12c

Viewed 1000+ times

You Asked

Hi ,

I have faced a situation where sql id plan hash value is changed due stats gather on one of table


currently i dont understand why this stats gathering cause chnage in plan and due to which execution time is poor now

can you guide what i need to check here

and Connor said...

You haven't really given us a lot to work with - *any* kind of stats change *might* result in a different plan.

If you were happy with the plan before the stats change, then perhaps look at:

- reverting the stats to their previous value, eg

https://blog.dbi-services.com/how-to-retrieve-previous-table-statistics-using-oracle-dbmsstats/

- using SQL Plan Management to lock down the plan

https://blogs.oracle.com/optimizer/how-to-use-sql-plan-management

Rating

  (1 rating)

Is this answer out of date? If it is, please let us know via a Comment

Comments

SPM on 12c

Rajeshwaran, Jeyabal, May 14, 2018 - 12:33 pm UTC

Since you were on 12c, it is now possible to get historical plans from AWR and loaded them into SPM.

https://sqlmaria.com/2017/12/19/sql-plan-management-selective-automatic-plan-capture-now-available/
more

Connor and Chris don't just spend all day on AskTOM. You can also catch regular content via Connor's blog and Chris's blog. Or if video is more your thing, check out Connor's latest video and Chris's latest video from their Youtube channels. And of course, keep up to date with AskTOM via the official twitter account.

More to Explore

Performance

Get all the information about database performance in the Database Performance guide.