Oracle内部视图:X$BH

REM List Buffer Cache Details

SET LINESIZE 200 PAGESIZE 1400

SELECT /*+ ORDERED USE_HASH(o u) MERGE */
DECODE(obj#,
NULL,
to_char(bh.obj),
u.name || '.' || o.name) name,
COUNT(*) total,
SUM(DECODE((DECODE(lru_flag, 8, 1, 0) + DECODE(SIGN(tch - 2), 1, 1, 0)),
2,
1,
1,
1,
0)) hot,
SUM(DECODE(DECODE(SIGN(lru_flag - 8), 1, 0, 0, 0, 1) +
DECODE(tch, 2, 1, 1, 1, 0, 1, 0),
2,
1,
1,
0,
0)) cold,
SUM(DECODE(BITAND(flag, POWER(2, 19)), 0, 0, 1)) fts,
SUM(tch) total_tch,
ROUND(AVG(tch), 2) avg_tch,
MAX(tch) max_tch,
MIN(tch) min_tch
FROM x$bh bh, sys.obj$ o, sys.user$ u
WHERE
bh.obj <> 4294967295
AND bh.state in (1, 2, 3)
AND bh.obj = o.dataobj#(+)
AND bh.inst_id = USERENV('INSTANCE')
AND o.owner# = u.user#(+)
--   AND o.owner# > 5
AND u.name NOT like 'AURORA$%'
GROUP BY DECODE(obj#,
NULL,
to_char(bh.obj),
u.name || '.' || o.name)
ORDER BY  total desc
/

COLUMN object_name FORMAT A30

SELECT t.name AS tablespace_name,
o.object_name,
SUM(DECODE(bh.status, 'free', 1, 0)) AS free,
SUM(DECODE(bh.status, 'xcur', 1, 0)) AS xcur,
SUM(DECODE(bh.status, 'scur', 1, 0)) AS scur,
SUM(DECODE(bh.status, 'cr', 1, 0)) AS cr,
SUM(DECODE(bh.status, 'read', 1, 0)) AS read,
SUM(DECODE(bh.status, 'mrec', 1, 0)) AS mrec,
SUM(DECODE(bh.status, 'irec', 1, 0)) AS irec
FROM   v$bh bh
JOIN dba_objects o ON o.data_object_id = bh.objd
JOIN v$tablespace t ON t.ts# = bh.ts#
GROUP BY t.name, o.object_name
order by xcur desc
/

set pages 999
set lines 92

ttitle 'Contents of Data Buffers'

drop view buffer_map;

create view buffer_map as
select
o.owner          owner,
o.object_name    object_name,
o.subobject_name subobject_name,
o.object_type    object_type,
count(distinct file# || block#)         num_blocks
from
dba_objects  o,
v$bh         bh
where
o.data_object_id  = bh.objd
-- and  o.owner not in ('SYS','SYSTEM')
and
bh.status != 'free'
group by
o.owner,
o.object_name,
o.subobject_name,
o.object_type
order by
count(distinct file# || block#) desc
;

column c0 heading "Owner"                                    format a12
column c1 heading "Object|Name"                              format a30
column c2 heading "Object|Type"                              format a8
column c3 heading "Number of|Blocks in|Buffer|Cache"         format 99,999,999
column c4 heading "Percentage|of object|blocks in|Buffer"    format 999
column c5 heading "Buffer|Pool"                              format a7
column c6 heading "Block|Size"                               format 99,999

select
buffer_map.owner                                          c0,
object_name                                       c1,
case when object_type = 'TABLE PARTITION' then 'TAB PART'
when object_type = 'INDEX PARTITION' then 'IDX PART'
else object_type end c2,
sum(num_blocks)                                     c3,
(sum(num_blocks)/greatest(sum(blocks), .001))*100 c4,
buffer_pool                                       c5,
sum(bytes)/sum(blocks)                            c6
from
buffer_map,
dba_segments s
where
s.segment_name = buffer_map.object_name
and
s.owner = buffer_map.owner
and
s.segment_type = buffer_map.object_type
and
nvl(s.partition_name,'-') = nvl(buffer_map.subobject_name,'-')
group by
buffer_map.owner,
object_name,
object_type,
buffer_pool
having
sum(num_blocks) > 10
order by
sum(num_blocks) desc
;

REM dbbuffer

select decode(pd.bp_id,1,'KEEP',2,'RECYCLE',3,'DEFAULT',
4,'2K SUBCACHE',5,'4K SUBCACHE',6,'8K SUBCACHE',
7,'16K SUBCACHE',8,'32KSUBCACHE','UNKNOWN') subcache,
bh.object_name,bh.blocks
from x$kcbwds ds,x$kcbwbpd pd,(select /*+ use_hash(x) */ set_ds,
o.name object_name,count(*) BLOCKS
from obj$ o, x$bh x where o.dataobj# = x.obj
and x.state !=0 and o.owner# !=0
group by set_ds,o.name) bh
where ds.set_id >= pd.bp_lo_sid
and ds.set_id <= pd.bp_hi_sid
and pd.bp_size != 0
and ds.addr=bh.set_ds;

column segment_name format a35
select /*+ RULE */
e.owner ||'.'|| e.segment_name  segment_name,
e.extent_id  extent#,
x.dlk - e.block_id + 1  block#,
x.tch,
l.child#
from
sys.v$latch_children  l,
sys.x$bh  x,
sys.dba_extents  e
where
x.hladdr  = '&ADDR' and
e.file_id = x.file# and
x.hladdr = l.addr and
x.dk between e.block_id and e.block_id + e.blocks -1
order by x.tch desc
/

with bh_lc as
(select /*+ ORDERED */
lc.addr, lc.child#, lc.gets, lc.misses, lc.immediate_gets,
lc.immediate_misses, lc.spin_gets, lc.sleeps,
bh.hladdr, bh.tch tch, bh.file#, bh.dk, bh.class,
bh.state, bh.obj
from
x$kslld ld,
v$session_wait sw,
v$latch_children lc,
x$bh bh
where lc.addr =sw.p1raw
and sw.p2= ld.indx
and ld.kslldnam='cache buffers chains'
and lower(sw.event) like '%latch%'
and sw.state='WAITING'
and bh.hladdr=lc.addr
)
select bh_lc.hladdr, bh_lc.tch, o.owner, o.object_name, o.object_type,
bh_lc.child#, bh_lc.gets,
bh_lc.misses, bh_lc.immediate_gets,
bh_lc.immediate_misses, spin_gets, sleeps
from
bh_lc,
dba_objects o
where bh_lc.obj = o.object_id(+)
union
select bh_lc.hladdr, bh_lc.tch, o.owner, o.object_name, o.object_type,
bh_lc.child#, bh_lc.gets, bh_lc.misses, bh_lc.immediate_gets,
bh_lc.immediate_misses, spin_gets, sleeps
from
bh_lc,
dba_objects o
where bh_lc.obj = o.data_object_id(+)
order by 1,2 desc
/

col class form A10
select decode(greatest(class,10),10,decode(class,1,'Data',2
,'Sort',4,'Header',to_char(class)),'Rollback') "Class",
sum(decode(bitand(flag,1),1,0,1)) "Not Dirty",
sum(decode(bitand(flag,1),1,1,0)) "Dirty",
sum(dirty_queue) "On Dirty",count(*) "Total"
from x$bh
group by decode(greatest(class,10),10,decode(class,1,'Data',2
,'Sort',4,'Header',to_char(class)),'Rollback')
/

Oracle内部视图:X$BH

X$BH Fixed Table Buffer Cache Diagram

Column     Type Description
~~~~~~     ~~~~~ ~~~~~~~~~~~
ADDR        RAW(4) Hex address of the Buffer Header.
INDX        NUMBER Buffer Header number
BUF#        NUMBER
HLADDR      RAW(4) Hash Chain Latch Address
See . ADDR

LRU_FLAG    NUMBER     8.1+ LRU flag
KCBBHLDF   0x01     8.1  LRU Dump Flag used in debug print routine
KCBBHLMT   0x02     8.1  moved to tail of lru (for extended stats)
KCBBHLAL   0x04     8.1  on auxiliary list
KCBBHLHB   0x08     8.1  hot buffer - not in cold portion of lru

FLAG        NUMBER
KCBBHFBD   0x00001       buffer dirty
KCBBHFAM   0x00002  7.3  about to modify; try not to start io
KCBBHFAM   0x00002  8.0  about to modify; try not to start io
KCBBHNAC   0x00002  8.1  notify dbwr after change
KCBBHFMS   0x00004       modification started, no new writes
KCBBHFBL   0x00008       block logged
KCBBHFTD   0x00010       temporary data - no redo for changes
KCBBHFBW   0x00020       being written; can't modify
KCBBHFWW   0x00040       waiting for write to finish
KCBBHFCK   0x00080  7.3  checkpoint asap
0x00080  8.0  not used
KCBBHFMW   0x00080  8.1  multiple waiters when gc lock acquired
KCBBHFRR   0x00100       recovery reading, do not reuse, being read
KCBBHFUL   0x00200       unlink from lock element - make non-current
KCBBHFDG   0x00400       write block & stop using for lock down grade
KCBBHFCW   0x00800       write block for cross instance call
KCBBHFCR   0x01000       reading from disk into KCBBHCR buffer
KCBBHFGC   0x02000       has been gotten in current mode
KCBBHFST   0x04000       stale - unused CR buf made from current
0x08000  7.3  Not used.
KCBBHFDP   0x08000  8.0  deferred ping
KCBBHFDP   0x08000  8.1  deferred ping
KCBBHFDA   0x10000       Direct Access to buffer contents
KCBBHFHD   0x20000       Hash chain Dump used in debug print routine
KCBBHFIR   0x40000       Ignore Redo for instance recovery
KCBBHFSQ   0x80000       sequential scan only flag
KCBBHFNW  0x100000  7.3  Set to indicate a buffer that is NEW
0x100000  8.0  Not used
KCBBHFBP  0x100000  8.1  Indicates that buffer was prefetched
KCBBHFRW  0x200000  7.3  re-write if being written (sort)
0x200000  8.0  Not used
KCBBHFFW  0x200000  8.1  Buffer has been written once
KCBBHFFB  0x400000       buffer is "logically" flushed
KCBBHFRS  0x800000       ReSilvered already - do not redirty
KCBBHFKW 0x1000000  7.3  ckpt writing flag to avoid rescan */
0x1000000  8.0  Not used
KCBBHDRC 0x1000000  8.1  buffer is nocache
0x2000000  7.3  Not used
KCBBHFRG 0x2000000  8.0  Redo Generated since block read
KCBBHFRG 0x2000000  8.1  Redo Generated since block read
KCBBHFWS 0x10000000 8.0  Skipped write for checkpoint.
KCBBHFDB 0x20000000 8.1  buffer is directly from a foreign DB
KCBBHFAW 0x40000000 8.0  Flush after writing
KCBBHFAW 0x40000000 8.1  Flush after writing

TS#         NUMBER 8.X Tablespace number
DBARFIL     NUMBER 8.X Relative file number of block
DBAFIL      NUMBER 7.3 File number of block
DB      NUMBER Block number of block
CLASS       NUMBER See Note 33434.1
1,'data block',
2,'sort block',
3,'save undo block',
4,'segment header',
5,'save undo header',
6,'free list',
7,'extent map',
8,'1st level bmb',
9,'2nd level bmb',
10,'3rd level bmb',
11,'bitmap block',
12,'bitmap index block',
13,'file header block',
14,'unused',
15,'system undo header',
16,'system undo block',
17,'undo header',
18,'undo block'                -- since 10g

STATE       NUMBER
KCBBHFREE         0       buffer free
KCBBHEXLCUR       1       buffer current (and if DFS locked X)
KCBBHSHRCUR       2       buffer current (and if DFS locked S)
KCBBHCR           3       buffer consistant read
KCBBHREADING      4       Being read
KCBBHMRECOVERY    5       media recovery (current & special)
KCBBHIRECOVERY    6       Instance recovery (somewhat special)

MODE_HELD   NUMBER    Mode buffer held in (MODE pre 7.3)
0=KCBMNULL, KCBMSHARE, KCBMEXCL

CHANGES     NUMBER
CSTATE      NUMBER
X_TO_NULL   NUMBER Count of PINGS out (OPS)
DIRTY_QUEUE NUMBER You wont normally see buffers on the LRUW
LE_ADDR     RAW(4) Lock Element address (OPS)
SET_DS      RAW(4) Buffer cache set this buffer is under
OBJ         NUMBER       Data object number
TCH     NUMBER 8.1 Touch Count
TIM     NUMBER 8.1 Touch Time
BA          RAW(4)
CR_SCN_BAS  NUMBER       Consistent Read SCN base
CR_SCN_WRP  NUMBER       Consistent Read SCN wrap
CR_XID_USN  NUMBER CR XID Undo segment no
CR_XID_SLT  NUMBER CR XID slot
CR_XID_SQN  NUMBER CR XID Sequence
CR_UBA_FIL  NUMBER CR UBA file
CR_UBA_BLK  NUMBER CR UBA Block
CR_UBA_SEQ  NUMBER CR UBA sequence
CR_UBA_REC  NUMBER CR UBA record
CR_SFL      NUMBER
LRBA_SEQ    NUMBER } Lowest RBA needed to recover block in cache
LRBA_BNO    NUMBER }
LRBA_BOF    NUMBER }

HRBA_SEQ    NUMBER } Redo RBA to be flushed BEFORE this block
HRBA_BNO    NUMBER } can be written out
HRBA_BOF    NUMBER       }

RRBA_SEQ    NUMBER } Block recovery RBA
RRBA_BNO    NUMBER }
RRBA_BOF    NUMBER }
NXT_HASH    NUMBER Next buffer on this hash chain
PRV_HASH    NUMBER Previous buffer on this hash chain
NXT_LRU     NUMBER Next buffer on the LRU
PRV_LRU     NUMBER Previous buffer on the LRU
US_NXT      RAW(4)
US_PRV      RAW(4)
WA_NXT      RAW(4)
WA_PRV      RAW(4)
ACC         RAW(4)
MOD         RAW(4)