Performance Degradation On Statistics For Large Partitioned Tables After Upgrade To 19c

Massive Performance Degradation On Statistics For Large Partitioned Tables After Upgrade To 19c (Doc ID 2611336.1)

Last updated on MAY 01, 2020

BUG 27268249 - ENHANCE INDEX NDK STATISTICS GATHERINGW

 it's recommended by change the fix control to disable 27268249 either at the session level or the system level: 
alter session set "_fix_control"='27268249:0';
or
alter system set "_fix_control"='27268249:0';
+++delete existing statistics:
sql> exec DBMS_STATS.DELETE_TABLE_STATS ('<owner-name>','<table-name>', partname => '<part-name>');
++ regather state++++
begin
 DBMS_STATS.gather_table_stats(ownname => '<owner-name>'
 ,tabname => '<table-name>'
 ,partname => NULL
 ,DEGREE => 1
 ,CASCADE => TRUE
 ,no_invalidate =>FALSE
 );
 end;
 /
On Jul 1, 2022 oracle 
reference :  
Ref Doc ID 2611336.1
Patch 33427856: GATHERING STATISTICS FOR INDEXES ON LARGE TABLES MAY BE TIME-CONSUMING