Search notes:

Oracle PLAN_TABLE: column PROJECTION

(upd=4,5,6,7; cmp=2,3) …
(#keys=0) …
(rowset=1019) …
VALUE(A0)[4000]

rowset

(rowset=n) indicates that «this» plan step processes n rows in one batch (rather than process one row at a time).
See also events 10055 and 10123

Always NULL in DBA_HIST_SQL_PLAN

The value of projection in dba_hist_sql_plan is always null, the following query returns 0:
select
   count(*)
from
   dba_hist_sql_plan
where
   projection is not null;  

See also

plan_table

Links

Researching plan_table column projection information (rowset and count)

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