Oracle Scratchpad

February 12, 2014 Upgrade

Filed under: Oracle,Upgrades — Jonathan Lewis @ 6:01 pm BST Feb 12,2014

A warning on Oracle-L from Chris Dunscombe: If you’ve got a large stats history – with lots of histogram data – then the upgrade could take an unexpectedly long time. Presumably the same is true if you upgrade from (or earlier) to 12c.



  1. Hi Jonathan,

    I hope we have undocumented parameter “_optim_dict_stats_at_db_cr_upg” =FALSE” it would disable the stats collection, so we can utilize during the upgrade and it would minimize the things.

    – Thanks
    Pavan Kumar N

    Comment by Pavan Kumar — February 13, 2014 @ 2:59 am BST Feb 13,2014 | Reply

    • Pavan,

      Thanks for the comment. I see that that parameter goes back at least to

      I wonder if it gathers all dictionary stats unconditionally, or whether it gathers only for the objects with stale stats; and then I have to wonder whether the optimizer history and the AWR history count as dictionary stats – could be nasty if they do and you’re at a site that likes to keep the AWR for a year.

      Comment by Jonathan Lewis — February 13, 2014 @ 8:34 am BST Feb 13,2014 | Reply

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