today faced with ‘enq: TX – index contention’

awr shows

helped to make partition index on nonpartition table:

drop index ARADMIN.IT3060;
CREATE UNIQUE INDEX ARADMIN.IT3060_P ON "ARADMIN"."T3060" ("C1") global partition by hash (C1) partitions 16 parallel 16 ;
drop index ARADMIN.T3060_IDX_12;
CREATE index ARADMIN.T3060_IDX_12 ON "ARADMIN"."T3060"  ("C536870937", "C7", "C536870938", "C1") global partition by hash ("C536870937", "C7", "C536870938", "C1")  partitions 16 parallel 16 TABLESPACE "ARSYSTEM" ;
drop index ARADMIN.T3060_IDX_11;
CREATE index ARADMIN.T3060_IDX_11 ON "ARADMIN"."T3060"  ("C536870922", "C7", "C536870941") global partition by hash ("C536870922", "C7", "C536870941")  partitions 16 parallel 16 TABLESPACE "ARSYSTEM" ;