Pre upgrade step - Ebs database upgrade

[satish]

Dear erman,

Does this below pre upgrade step require application to be down?
Or can it be run when the application is online? Pls suggest

Run Optimizer Statistics on existing 11.1.0.7 oracle database

When upgrading to Oracle Database 11g Release 2 (11.2), optimizer statistics are collected for dictionary tables that lack statistics. This statistics collection can be time consuming for databases with a large number of dictionary tables, but statistics gathering only occurs for those tables that lack statistics or are significantly changed during the upgrade.

$ sqlplus “/as sysdba”

SQL> EXEC DBMS_STATS.GATHER_DICTIONARY_STATS;

Thanks,
Satish

[ErmanArslansOracleBlog]

Take a look at -> https://ermanarslan.blogspot.com/2016/12/rdbmsgrid-upgrading-rac-database-and.html


"GATHER_DICTIONARY_STATS" gathers statistics for dictionary schemas 'SYS', 'SYSTEM' and internal schemas of RDBMS components.

Oracle says: To decrease the amount of downtime incurred when collecting statistics, you can collect statistics prior to performing the actual database upgrade.

You can do it just before the upgrade, I mean during your upgrade, when you get application downtime. (if you feel the prod app will be affected by that)
However; if it is taking a lot of time (you already tested it on your TEST env right?), then you may start executing it before the upgrade (in the upgrade day for instance, not too early but still at a time before you get the app downtime)