----------------------------------------------------------------------------------------------------------------
| Id? | Operation? ? ? ? ? ? ? ? | Name? ? ? ? ? ? ? ? | Rows? | Bytes | Cost (%CPU)| Time? ? | Pstart| Pstop |
----------------------------------------------------------------------------------------------------------------
|? 0 | SELECT STATEMENT? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? 5 |? ? 80 |? ? 21? (10)| 00:00:01 |? ? ? |? ? ? |
|? 1 |? VIEW? ? ? ? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? 5 |? ? 80 |? ? 21? (10)| 00:00:01 |? ? ? |? ? ? |
|? 2 |? UNION-ALL? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? ? |? ? ? |? ? ? ? ? ? |? ? ? ? ? |? ? ? |? ? ? |
|? 3 |? ? PARTITION RANGE SINGLE|? ? ? ? ? ? ? ? ? ? |? ? 1 |? ? 44 |? ? 14? (0)| 00:00:01 |? ? 1 |? ? 1 |
|*? 4 |? ? TABLE ACCESS FULL? ? | SYS_FBA_HIST_549255 |? ? 1 |? ? 44 |? ? 14? (0)| 00:00:01 |? ? 1 |? ? 1 |
|*? 5 |? ? FILTER? ? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? ? |? ? ? |? ? ? ? ? ? |? ? ? ? ? |? ? ? |? ? ? |
|? 6 |? ? MERGE JOIN OUTER? ? |? ? ? ? ? ? ? ? ? ? |? ? 4 |? 8224 |? ? 7? (29)| 00:00:01 |? ? ? |? ? ? |
|? 7 |? ? ? SORT JOIN? ? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? 4 |? 112 |? ? 3? (34)| 00:00:01 |? ? ? |? ? ? |
|*? 8 |? ? ? TABLE ACCESS FULL? | T0516_7? ? ? ? ? ? |? ? 4 |? 112 |? ? 2? (0)| 00:00:01 |? ? ? |? ? ? |
|*? 9 |? ? ? SORT JOIN? ? ? ? ? |? ? ? ? ? ? ? ? ? ? |? ? 2 |? 4056 |? ? 4? (25)| 00:00:01 |? ? ? |? ? ? |
|* 10 |? ? ? TABLE ACCESS FULL? | SYS_FBA_TCRV_549255 |? ? 2 |? 4056 |? ? 3? (0)| 00:00:01 |? ? ? |? ? ? |
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Predicate Information (identified by operation id):
---------------------------------------------------

? 4 - filter("ENDSCN">12723393908514 AND "ENDSCN"<=12723394060501 AND ("STARTSCN" IS NULL OR
? ? ? ? ? ? ? "STARTSCN"<=12723393908514) AND ("OPERATION" IS NULL OR "OPERATION"<>'D'))
? 5 - filter("STARTSCN"<=12723393908514 OR "STARTSCN" IS NULL)
? 8 - filter("T"."VERSIONS_STARTSCN" IS NULL)
? 9 - access("RID"(+)=ROWIDTOCHAR("T".ROWID))
? ? ? filter("RID"(+)=ROWIDTOCHAR("T".ROWID))
? 10 - filter(("ENDSCN"(+) IS NULL OR "ENDSCN"(+)>12723394060501) AND ("STARTSCN"(+) IS NULL OR
? ? ? ? ? ? ? "STARTSCN"(+)<12723394060501))
? ? ? ? ? ? ?
col OWNER_NAME format a10
set numwidth 4
col FLASHBACK_ARCHIVE_NAME format a10
col create_time format a35
col last_purge_time format a35
set linesize 140
select * from dba_flashback_archive_tables where table_name='T0516_7';? ? ? ? ? ? ?
TABLE_NAME? ? ? ? ? ? ? ? ? ? OWNER_NAME FLASHBACK_ ARCHIVE_TABLE_NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? STATUS
------------------------------ ---------- ---------- ----------------------------------------------------- -------------
T0516_7? ? ? ? ? ? ? ? ? ? ? ? SCOTT? ? ? FBA0513? ? SYS_FBA_HIST_549255? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ENABLED

--清空flashback archive
SYS@tstdb1-SQL> alter flashback archive FBA0513 purge all;

Flashback archive altered.

SQL> select count(*) from SYS_FBA_HIST_549255;

? COUNT(*)
----------
? ? ? ? 0

--再次查看执行计划SYS_FBA还在列，期间尝试过程flush shared_pool，修改undo_tablespace和重启instance，结果还是如此，这就有点不解了，本来认为Flashback archive被清空后flashback query应该去读取undo的
SQL> explain plan for select * from t0516_7 as of scn 12723393908514;

Explained.

SQL> set pagesize 100 linesize 150
SQL> select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 4190489988