#blocks below: 3712
mapblk 0x00000000 offset: 43
Level 1 BMB for High HWM block: 0x01002081
Level 1 BMB for Low HWM block: 0x01002001
--------------------------------------------------------
Segment Type: 1 nl2: 1 blksz: 8192 fbsz: 0
L2 Array start offset: 0x00001434
First Level 3 BMB: 0x00000000
L2 Hint for inserts: 0x01000399
Last Level 1 BMB: 0x01002081
Last Level II BMB: 0x01000399
Last Level III BMB: 0x00000000
Map Header:: next 0x00000000 #extents: 45 obj#: 23303 flag: 0x10000000
Inc # 0
Extent Map
-----------------------------------------------------------------
0x01000398 length: 8
%……………………
0x01002080 length: 128 --最后一个L1 DBA是8320号块，管理了128个块，高水位是8448号块，刚好是最后一个L1的最后一个数据块。
Auxillary Map
--------------------------------------------------------
Extent 0 : L1 dba: 0x01000398 Data dba: 0x0100039b
……………………
Extent 44 : L1 dba: 0x01002080 Data dba: 0x01002082 高水位应该就是这个L1管理的最后一个块：0x01002082 -8322号块，
--------------------------------------------------------
Second Level Bitmap block DBAs
--------------------------------------------------------
DBA 1: 0x01000399
对表做分析后
BYS@ bys3>analyze table test12 compute statistics;Table analyzed.
BYS@ bys3>select pct_free,pct_used,blocks,avg_row_len,chain_cnt from tabs where table_name='TEST12';
PCT_FREE PCT_USED BLOCKS AVG_ROW_LEN CHAIN_CNT
---------- ---------- ---------- ----------- ----------
10 3784 93 0
BYS@ bys3>set autotrace traceonly stat
BYS@ bys3>select * from test12;
280960 rows selected.
Elapsed: 00:00:05.46
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
22204 consistent gets
0 redo size
29190599 bytes sent via SQL*Net to client
206449 bytes received via SQL*Net from client
18732 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
280960 rows processed
DUMP信息与未做表分析时相同，不贴了。
######################
DELETE删除表中全部数据
BYS@ bys3>delete test12;280944 rows deleted.
BYS@ bys3>commit;
Commit complete.
BYS@ bys3>alter system checkpoint;
System altered.
BYS@ bys3>select header_block,header_file from dba_segments where segment_name='TEST12' and owner='BYS';
HEADER_BLOCK HEADER_FILE
------------ -----------
922 4
BYS@ bys3>select sum(blocks) from dba_extents where segment_name='TEST12' and owner='BYS';
SUM(BLOCKS)
-----------
3840
BYS@ bys3>select count(extent_id) from dba_extents where segment_name='TEST12' and owner='BYS';
COUNT(EXTENT_ID)
----------------
45
BYS@ bys3>analyze table test12 compute statistics;
Table analyzed.
BYS@ bys3>select pct_free,pct_used,blocks,avg_row_len,chain_cnt from tabs where table_name='TEST12';
PCT_FREE PCT_USED BLOCKS AVG_ROW_LEN CHAIN_CNT
---------- ---------- ---------- ----------- ----------
10 3784 0 0
System altered.
BYS@ bys3>select value from v$diag_info where name like 'De%';
VALUE
----------------------------------------------------------------------------------------------------
/u01/diag/rdbms/bys3/bys3/trace/bys3_ora_26054.trc
BYS@ bys3>set autotrace traceonly stat
BYS@ bys3>select * from test12;
no rows selected
Elapsed: 00:00:00.02
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
3721 consistent gets
2 physic