Oracle Cache Buffer Internals

Oracle Buffer CacheOracle Buffer CacheInternalsInternals

SUNDARSUNDAR

BY

AgendaAgenda

Buffer Cache Management concept Hash Algorithm Cache buffers chains Latch Hash buckets Cache/hash chain Block Header Buffer Cache Working sets Lists Cache buffer lru Latch Touch count Examples

Buffer cache

DBWR

Data buffer cache

I need file 29, block 13

is it already in the cache?

1GBBlack Box

13:12:38 SQL> select * from test1where id=100;

ID DESC1---------- ----------

100 BUFFER1

Elapsed: 00:00:00.00

13:12:38 SQL>

13:12:38 SQL> select * from test1where id=100;

ID DESC1---------- ----------

100 BUFFER1

Elapsed: 00:00:00.00

13:12:38 SQL>

PROCESS

SQL >

Transaction Layer

Lock Management Layer

Generic LayerOperating System Dependencies

Services Layer

Access LayerData Layer

User Program InterfaceOracle Call Interface

Net connection

UPIOCI

KT

KJKG

S

KS

KAKD

SQL >

Oracle Kernel Function Names

Recursive Program InterfaceRPI

DEFAULT

KEEP, RECYCLE

2K, 4K, 8K, 16K and 32K

Oracle rdbms Kernel

Cache LayerKC

Real worldReal worldproblemsproblems

ConceptConcept

Delivery person

Storage area

Delivery Addr

Storage Unit

Delivery personStorage areaStorage Unit #Delivery address

Delivery Management system

Delivery Addr

Location # 1

Location # 2

Location # 3

Location # 4

Location # 5

Location # 6

Location # 7

Location # n

Delivery person


5 15 16 21 14 2

13 17 12 22 30

24 4 7 25 29 23

1 11 18 8 27

10 19 20 3 26 9

Storage area

6

28

Security

Street/gate

00

Unique Item

Unit #

Delivery Addr

Location # 1

Location # 2

Location # 3

Location # 4

Location # 5

Location # 6

Location # 7

Location # n

5 15 16 21 14 2

13 17 12 22 30

24 4 7 25 29 23

1 11 18 8 27

10 19 20 3 26 9

Storage area

60

1

2

3

4

Street #Security #

28

Delivery person


9790837669 6255484134272013 6

9689827568 6154474033261912 5

9588817467 6053463932251811 4

9487807366 59524538312417103

10093867972 6558514437302316 9 2

9992857871 6457504336292215 8 1

9891847770 6356494235282114 7

151413121110987654321

6

5

4

3

2

1

0

MOD ( 10, 7) = 3 MOD ( 100, 7) = 2

H

ASH

Chains

Hash Algorithm

Delivery Addr.

Location # 1

Location # 2

Location # 3

Location # 4

Location # 5

Location # 6

Location # 7

Location # n

5 10 15 20 25 30

1 11 16 21 26

2 7 12 17 22 27

3 8 13 18 28

4 9 14 19 24 29

Storage area

6

2328

0

1

2

3

4

Street #Security #

Mod ( Storage area # / 5 )

Hash

mod ( 28 / 5 ) = 3

Delivery person


87654408854861

8760600656582

9795003218994

42156786783n

334432014432420

Time Waited

Total people Imm Get

TotalPeople waited

Total People visited

Street#/Gate #

Security Log

Buffer CacheBuffer Cache

Delivery person

Security

Storage area

Cache buffer Chains latch

Hash table /Bucket #

Street/gate #

Hash chain(BH)

Process

Data Block Loc

Security Logs v$latch_children

Real world to Oracle world

Delivery Addr.

Storage Unit # DBA # + Classes #

Latch #


Hash table /Bucket #

Buffer_cacheHash chain

Oracle rdbms

PROCESS # nPROCESS # n

012

Location # 1

Location # 2Location # 3Location # n

PROCESS

Building Hash Bucket


Storage areaSecurityDelivery person Delivery AddrStreet #

buffer tsn: 4rdba: 0x0740000d (29/13)scn: 0x0000.00054ec3 seq: 0x03 flg: 0x02 tail: 0x4ec30603frmt: 0x02 chkval: 0x0000 type: 0x06=trans data

buffer tsn: 4rdba: 0x0740000d (29/13)scn: 0x0000.00054ec3 seq: 0x03 flg: 0x02 tail: 0x4ec30603frmt: 0x02 chkval: 0x0000 type: 0x06=trans data

Save undo header5Segment header4Save undo block3Sort block2Data block1DescriptionClassBlock header

DataSegmentheader

L1BMB

L2BMB

dataFile SpaceHeader

DBA Classes

dba / Classes

n012345

Latch # n

Latch # 2

Latch # 1BH BH BH BH

BH BH BH BH

BH BH BH

BH BH BH BH

BH BH BH BH

BH BH BH BH


Buffer cacheHash chainHash table /Bucket #Cache buffer Chains latch

PROCESS #1

PROCESS #2

PROCESS #3

Server processes

BH = Block Header

Buffer_cache

BH BH BH BH BH

BH BH BH BH

0

1

Latch # 1

PROCESS #1

PROCESS #2

PROCESS #3

Cache buffer Chains latch Hash table Hash chain


Block Address

01Latch # 1

PROCESS #1

2

hash

Hash table Hash chain

DBA + Class

Buffer cache

BH BH

BH

BH BH BH

PROCESS


Reading a blockReading a block

Gets hash chain latch

walks along, does not find copy of block 29.13(file_id,block#)

gets cache buffers lru chain(LRU) latch

walks AUX list, finds empty buffer

Insert free buffer in the middle of the LRU - MAIN list

Add that header to hash ( BH )

Read the block to memory (buffer cache )

Release latches

Gets hash chain latch

walks along, does not find copy of block 29.13(file_id,block#)

gets cache buffers lru chain(LRU) latch

walks AUX list, finds empty buffer

Insert free buffer in the middle of the LRU - MAIN list

Add that header to hash ( BH )

Read the block to memory (buffer cache )

Release latches

Reading a block

Hash chain

rdba: 0x0740000d (29/13) class: 1

0

1

2

Hash table

BH BH BH

BH BH

BH

Oops!!Latch # 1

PROCESS #1

DBA + Class

hash

Reading a block

SQL >

Cache buffers lru chains

LRU #

REPL/LRU

LRU-WDBWR

PROCESS

Cache buffers lru chains

LRU - Least Recently Used

LRU - replacement list

LRU-W - write list

LRU - replacement list

LRU-W - write list

Buffer Headers are Linked one of the List

DBWR

disk

BH BH BH

BH BH BH

LRU

LRU-W

LRU Lists

1. Dirty Buffer2. Pinned Buffer3. Free Buffer

REPL/LRULRU-WLRU-XO

LRU-XR

LRU-REQ

Working Set

Main list

- pinned / dirty buffers

Auxiliary list

- Empty Buffers

Main list

- pinned / dirty buffers

Auxiliary list

- Empty Buffers

Each LRU contains

Main and Auxiliary Lists

REPL/LRU

LRU-W

MAIN

AUX

Hot End Cold End

MAIN

AUX

Sets # 1

BH BH BH BH BH0

1

2

n

BH BH BH BH BH BH

BH BH BH BH BH

BH BH BH

BH BH

BH BH BH

BH BH

BH BH BH BH

BH BH BH

BH

BH3

Sets # 1

Working Sets

Sets # 2 Sets # n

BH BH BH

BH BH

0

1Latch # 1

PROCESS #1

2 BH

DBA + Class

hash

rdba: 0x0740000d (29/13) class: 1


MAIN

AUX

Hot End Cold EndLRU List

LRU # 1

BH

Reading a block

Free Blocks

Midpoint Insertion

BH BH BH

BH BH

0

1Latch # 1

PROCESS #1

2 BH

DBA + Class

hash

rdba: 0x0740000d (29/13) class: 1


MAIN

AUX

Hot End Cold EndWorking sets

LRU # 1

BH

Free Blocks

Buffer cache

disk

Reading a block

PROCESS #1Midpoint Insertion

BH BH BH

BH BH

0

1Latch # 1

PROCESS #1

2 BH

DBA + Class

hash

rdba: 0x0740000d (29/13) class: 1


BHFound!!!

Reading a block

HEAD : [9ffcb018,9ffcb018]file#Block: (29/13)class : 1 block loc : 0x9fa00000status : XCURRENTobj : 17918Flags : only_sequential_accesslru : [9ffcb1a8,9ffcaf88]

HEAD : [9ffcb018,9ffcb018]file#Block: (29/13)class : 1 block loc : 0x9fa00000status : XCURRENTobj : 17918Flags : only_sequential_accesslru : [9ffcb1a8,9ffcaf88]

CHAIN: 16652 : BH (0x9ffcb018)

BH BH BH

BH BH BH

Buffer Header ( BH )

09FA00000

Memory

2F06C203

0000A206

09FA2BFF0

8K

Hash chain

Little bit about Little bit about Touch countTouch count

Block#

Touch count #

2 0

112

283

122

610

671

200

77 12

6 4

5122

MAIN

AUX

Read block 551

Update block

Hot End Cold End

Single-Block Reads

2 0

112

281

122

610

671

200

51

MAIN

Midpoint Insertion

77 12

6 4

5122

AUX

Read block 12

Hot End Cold End

Single-Block Reads

2 0

112

281

122

610

671

200

51

MAIN

2 0

112

281

123

610

671

200

51

MAIN

Increment touch count

Hot End Cold End

2 0

112

281

122

610

671

200

51

MAIN

Block movement

DBWR

77 12

6 4

5122

AUX

2 0

110

281

122

610

671

200

51

MAIN

PROCESS

12 13 14 15 16 17 1811 2019

DB_FILE_MULTIBLOCK_READ_COUNT = 8

Read block 40- 47

02 03 04 0501 080706

Update block

41 42 43 4440 474645

Hot End Cold End

Multi-Block Reads

19181716 4713 14 1512 46 45 44 43 42 4111 2040

Midpoint Insertion

Buffer cache

DBWR

Black Box

0123

n

BH BH BH BH

BH BH BH BH

BH BH BH

BH BH BH BH

BH BH BH BHLatch # n

Latch # 2

Latch # 1

LRU # 1

LRU # N

Hot End Cold EndCache buffer LRU latch

Working sets

Set # n

Set # 2

Set # 1

Buffer Cache Black Box

Buffer CacheBuffer CacheExample Example 11

SQL> show sgaTotal System Global Area 1979711488 bytesFixed Size 2085000 bytesVariable Size 889196408 bytesDatabase Buffers 1073741824 bytesRedo Buffers 14688256 bytes

Oracle SGA

Create tablespace buffertest DATAFILE '/mnt/poc/ETLTEST/buffertest_01.dbf' size 5M autoextend on extent management local SEGMENT SPACE MANAGEMENT AUTO;

SQL> insert into test1 VALUES (100,'BUFFER1');

1 row created.

SQL > Create table test1 (id number, desc1 varchar2(10) ) tablespace buffertest ;

SQL> select object_id,object_name from dba_objectswhere object_name='TEST1

OBJECT_ID OBJECT_NAM---------- ----------

17918 TEST1

Data Input

SQL> select * from test1;ID DESC1

---------- ----------

100 BUFFER1

SQL> SELECT SEGMENT_NAME,HEADER_FILE,HEADER_BLOCK,BYTES,BLOCKS,EXTENTSFROM DBA_SEGMENTS WHERE SEGMENT_NAME LIKE 'TEST1'

SEGMENT_NA HEADER_FILE HEADER_BLOCK BYTES BLOCKS EXTENTS---------- ----------- ------------ ---------- ---------- ----------

TEST1 29 11 65536 8 1

SQL> SELECT SEGMENT_NAME,HEADER_FILE,HEADER_BLOCK,BYTES,BLOCKS,EXTENTSFROM DBA_SEGMENTS WHERE SEGMENT_NAME LIKE 'TEST1'


TEST1 29 11 65536 8 1

1 select ROWID,DBMS_ROWID.ROWID_OBJECT(rowid) "OBJECT",2 DBMS_ROWID.ROWID_RELATIVE_FNO(rowid) "FILE",3 DBMS_ROWID.ROWID_BLOCK_NUMBER(rowid) "BLOCK",4 DBMS_ROWID.ROWID_ROW_NUMBER(rowid) "ROW",ID,DESC15* from TEST1

ROWID OBJECT FILE BLOCK ROW ID DESC1------------------ ---------- ---------- ---------- ---------- ---------- ----------

AAAEX+AAdAAAAANAAA 17918 29 13 0 100 BUFFER1

1 select ROWID,DBMS_ROWID.ROWID_OBJECT(rowid) "OBJECT",2 DBMS_ROWID.ROWID_RELATIVE_FNO(rowid) "FILE",3 DBMS_ROWID.ROWID_BLOCK_NUMBER(rowid) "BLOCK",4 DBMS_ROWID.ROWID_ROW_NUMBER(rowid) "ROW",ID,DESC15* from TEST1

ROWID OBJECT FILE BLOCK ROW ID DESC1------------------ ---------- ---------- ---------- ---------- ---------- ----------

AAAEX+AAdAAAAANAAA 17918 29 13 0 100 BUFFER1

Data Input

SQL> select OWNER,SEGMENT_NAME,EXTENT_ID,FILE_ID,BLOCK_ID,BYTES,BLOCKS from dba_extents where SEGMENT_NAME='TEST1';

OWNER SEGMENT_NA EXTENT_ID FILE_ID BLOCK_ID BYTES BLOCKS----- ---------- ---------- ---------- ---------- ---------- ----------

SYS TEST1 0 29 9 65536 8

SQL> select OWNER,SEGMENT_NAME,EXTENT_ID,FILE_ID,BLOCK_ID,BYTES,BLOCKS from dba_extents where SEGMENT_NAME='TEST1';

OWNER SEGMENT_NA EXTENT_ID FILE_ID BLOCK_ID BYTES BLOCKS----- ---------- ---------- ---------- ---------- ---------- ----------

SYS TEST1 0 29 9 65536 8

SQL> select * from test1;

Execution Plan----------------------------------------------------------

Plan hash value: 4122059633

---------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |---------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 1 | 11 | 3 (0)| 00:00:01 || 1 | TABLE ACCESS FULL| TEST1 | 1 | 11 | 3 (0)| 00:00:01 |---------------------------------------------------------------------------

SQL> select * from test1;

Execution Plan----------------------------------------------------------


---------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |---------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 1 | 11 | 3 (0)| 00:00:01 || 1 | TABLE ACCESS FULL| TEST1 | 1 | 11 | 3 (0)| 00:00:01 |---------------------------------------------------------------------------

SQL> select * from test1;ID DESC1

---------- ----------

100 BUFFER1

Explain Plan

DataSegmentheader

L1BMB

L2BMB

data

11109 12 13 14 15 162

SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode(state,0,'free',1,'xcur',2,'scur',3,'cr', 4,'read',5,'mrec' ,6,'irec',7,'write',8,'pi') statefrom x$bh where DBARFIL=29 order by 3;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STATE-------- ------ ------ ------- --------- --------- -----

0D44DC9A8 2 29 0A0550000 0D44DCBE0 0D44DCBE0 xcur0D47FD418 11 29 09F668000 0D47FD610 09FFCC228 cr0D47FD418 11 29 09FA22000 09FFAC758 0D47FD610 xcur0D45DD590 12 29 09FE24000 0D45DD748 0D45DD748 xcur0D43BD708 13 29 09F296000 0D43BD880 0D43BD880 xcur0D472D880 14 29 09F666000 0D472D9B8 0D472D9B8 xcur0D450D9F8 15 29 09FA20000 0D450DAF0 0D450DAF0 xcur0D487DB70 16 29 09FE22000 0D487DC28 0D487DC28 xcur

SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode(state,0,'free',1,'xcur',2,'scur',3,'cr', 4,'read',5,'mrec' ,6,'irec',7,'write',8,'pi') statefrom x$bh where DBARFIL=29 order by 3;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STATE-------- ------ ------ ------- --------- --------- -----

0D44DC9A8 2 29 0A0550000 0D44DCBE0 0D44DCBE0 xcur0D47FD418 11 29 09F668000 0D47FD610 09FFCC228 cr0D47FD418 11 29 09FA22000 09FFAC758 0D47FD610 xcur0D45DD590 12 29 09FE24000 0D45DD748 0D45DD748 xcur0D43BD708 13 29 09F296000 0D43BD880 0D43BD880 xcur0D472D880 14 29 09F666000 0D472D9B8 0D472D9B8 xcur0D450D9F8 15 29 09FA20000 0D450DAF0 0D450DAF0 xcur0D487DB70 16 29 09FE22000 0D487DC28 0D487DC28 xcur

X$BH

File SpaceHeader

64k ( 8 blocks )

16652

69528

78532

116784

178664

216916

240544

09F668000

09FE24000

09FA22000

09FE22000

09F296000

09F666000

09FA20000

0A0550000

09F66800009FA22000

0A0550000

09FE24000

09F296000

09F666000

09FA20000

09FE22000

(0x9ff8bfc8)

(0xa0fa3298)

(0x9ffcc118)

(0x9ffee338)

(0x9ffac648)

(0x9ffee228)

0x9ffcc228) (0x9ffac758)

0D44DC9A8

0D47FD418

0D45DD590

0D43BD708

0D472D880

0D450D9F8

0D487DB70

Cache buffer BH dump


Hash table /Bucket # Hash chain ( BH )

Buffer cacheaddresses

2

13

12

11

14

15

16

CHAIN: 69528 LOC: 0xd44dcbe0 HEAD: [a0fa3298,a0fa3298]BH (0xa0fa3298) file#: 29 rdba: 0x07400002 (29/2) class: 13 ba: 0xa0550000

set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: -1 objn: 1 tsn: 28 afn: 29hash: [d44dcbe0,d44dcbe0] lru: [a0fa3428,a0fa3208]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [cf3cf018,cf3cf018]st: XCURRENT md: NULL tch: 1flags: gotten_in_current_modeLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fab68 seq: 0x02 flg: 0x04 tail: 0xab681d02frmt: 0x02 chkval: 0x43f5 type: 0x1d=KTFB Bitmapped File Space Header

CHAIN: 69528 LOC: 0xd44dcbe0 HEAD: [a0fa3298,a0fa3298]BH (0xa0fa3298) file#: 29 rdba: 0x07400002 (29/2) class: 13 ba: 0xa0550000

set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: -1 objn: 1 tsn: 28 afn: 29hash: [d44dcbe0,d44dcbe0] lru: [a0fa3428,a0fa3208]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [cf3cf018,cf3cf018]st: XCURRENT md: NULL tch: 1flags: gotten_in_current_modeLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fab68 seq: 0x02 flg: 0x04 tail: 0xab681d02frmt: 0x02 chkval: 0x43f5 type: 0x1d=KTFB Bitmapped File Space Header


BH (0x9ffcc228) file#: 29 rdba: 0x0740000b (29/11) class: 4 ba: 0x9fa22000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [9ffac758,d47fd610] lru: [9ffce4a8,9ffcc198]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0e1750,9ffcc208]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x02 flg: 0x04 tail: 0xabab2302frmt: 0x02 chkval: 0xee4e type: 0x23=PAGETABLE SEGMENT HEADER

BH (0x9ffac758) file#: 29 rdba: 0x0740000b (29/11) class: 4 ba: 0x9f668000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 15dbwrid: 1 obj: 17918 objn: -1 tsn: 28 afn: 29hash: [d47fd610,9ffcc228] lru: [9ffad5a8,9ffac6c8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0ed7e8,9ffac738]st: CR md: NULL tch: 1cr: [scn: 0x0.3fb424],[xid: 0x0.0.0],[uba: 0x0.0.0],[cls: 0x0.3fb424],[sfl: 0x0]flags:scn: 0x0000.003fabab seq: 0x02 flg: 0x04 tail: 0xabab2302frmt: 0x02 chkval: 0xee4e type: 0x23=PAGETABLE SEGMENT HEADER

BH (0x9ffcc228) file#: 29 rdba: 0x0740000b (29/11) class: 4 ba: 0x9fa22000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [9ffac758,d47fd610] lru: [9ffce4a8,9ffcc198]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0e1750,9ffcc208]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x02 flg: 0x04 tail: 0xabab2302frmt: 0x02 chkval: 0xee4e type: 0x23=PAGETABLE SEGMENT HEADER

BH (0x9ffac758) file#: 29 rdba: 0x0740000b (29/11) class: 4 ba: 0x9f668000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 15dbwrid: 1 obj: 17918 objn: -1 tsn: 28 afn: 29hash: [d47fd610,9ffcc228] lru: [9ffad5a8,9ffac6c8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0ed7e8,9ffac738]st: CR md: NULL tch: 1cr: [scn: 0x0.3fb424],[xid: 0x0.0.0],[uba: 0x0.0.0],[cls: 0x0.3fb424],[sfl: 0x0]flags:scn: 0x0000.003fabab seq: 0x02 flg: 0x04 tail: 0xabab2302frmt: 0x02 chkval: 0xee4e type: 0x23=PAGETABLE SEGMENT HEADER

CHAIN: 216916 LOC: 0xd47fd610 HEAD: [9ffcc228,9ffac758]


CHAIN: 16651 LOC: 0xd43bd870 HEAD: [NULL]CHAIN: 16652 LOC: 0xd43bd880 HEAD: [9ff8bfc8,9ff8bfc8]

BH (0x9ff8bfc8) file#: 29 rdba: 0x0740000d (29/13) class: 1 ba: 0x9f296000set: 11 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 24dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d43bd880,d43bd880] lru: [9ff8c158,9ff8bf38]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0e2860,ce0e2860]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x03 flg: 0x06 tail: 0xabab0603frmt: 0x02 chkval: 0x0c13 type: 0x06=trans data

CHAIN: 16651 LOC: 0xd43bd870 HEAD: [NULL]CHAIN: 16652 LOC: 0xd43bd880 HEAD: [9ff8bfc8,9ff8bfc8]

BH (0x9ff8bfc8) file#: 29 rdba: 0x0740000d (29/13) class: 1 ba: 0x9f296000set: 11 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 24dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d43bd880,d43bd880] lru: [9ff8c158,9ff8bf38]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0e2860,ce0e2860]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x03 flg: 0x06 tail: 0xabab0603frmt: 0x02 chkval: 0x0c13 type: 0x06=trans data

CHAIN: 116784 LOC: 0xd45dd748 HEAD: [9ffee338,9ffee338]BH (0x9ffee338) file#: 29 rdba: 0x0740000c (29/12) class: 1 ba: 0x9fe24000set: 10 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 27dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d45dd748,d45dd748] lru: [9ffee4c8,9ffee2a8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0f2988,9ffee318]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x1a0e type: 0x06=trans data

CHAIN: 116784 LOC: 0xd45dd748 HEAD: [9ffee338,9ffee338]BH (0x9ffee338) file#: 29 rdba: 0x0740000c (29/12) class: 1 ba: 0x9fe24000set: 10 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 27dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d45dd748,d45dd748] lru: [9ffee4c8,9ffee2a8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0f2988,9ffee318]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x1a0e type: 0x06=trans data


CHAIN: 178664 LOC: 0xd472d9b8 HEAD: [9ffac648,9ffac648]BH (0x9ffac648) file#: 29 rdba: 0x0740000e (29/14) class: 1 ba: 0x9f666000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 15dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d472d9b8,d472d9b8] lru: [9ffac7d8,9ffac5b8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffac848,ce0ed7e8]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x71a8 type: 0x06=trans data

CHAIN: 178664 LOC: 0xd472d9b8 HEAD: [9ffac648,9ffac648]BH (0x9ffac648) file#: 29 rdba: 0x0740000e (29/14) class: 1 ba: 0x9f666000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 15dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d472d9b8,d472d9b8] lru: [9ffac7d8,9ffac5b8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffac848,ce0ed7e8]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x71a8 type: 0x06=trans data

CHAIN: 78532 LOC: 0xd450daf0 HEAD: [9ffcc118,9ffcc118]BH (0x9ffcc118) file#: 29 rdba: 0x0740000f (29/15) class: 1 ba: 0x9fa20000

set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d450daf0,d450daf0] lru: [9ffcc2a8,9ffcc088]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffcc318,ce0e1750]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]buffer tsn: 28 rdba: 0x0740000f (29/15)scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0xc95c type: 0x06=trans data

CHAIN: 78532 LOC: 0xd450daf0 HEAD: [9ffcc118,9ffcc118]BH (0x9ffcc118) file#: 29 rdba: 0x0740000f (29/15) class: 1 ba: 0x9fa20000

set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 22dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d450daf0,d450daf0] lru: [9ffcc2a8,9ffcc088]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffcc318,ce0e1750]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]buffer tsn: 28 rdba: 0x0740000f (29/15)scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0xc95c type: 0x06=trans data


CHAIN: 240544 LOC: 0xd487dc28 HEAD: [9ffee228,9ffee228]BH (0x9ffee228) file#: 29 rdba: 0x07400010 (29/16) class: 1 ba: 0x9fe22000

set: 10 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 27dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d487dc28,d487dc28] lru: [9ffee3b8,9ffee198]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffee428,ce0f2988]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x96a9 type: 0x06=trans data

CHAIN: 240544 LOC: 0xd487dc28 HEAD: [9ffee228,9ffee228]BH (0x9ffee228) file#: 29 rdba: 0x07400010 (29/16) class: 1 ba: 0x9fe22000

set: 10 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 27dbwrid: 1 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d487dc28,d487dc28] lru: [9ffee3b8,9ffee198]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [9ffee428,ce0f2988]st: XCURRENT md: NULL tch: 1flags: only_sequential_accessLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x01 flg: 0x04 tail: 0xabab0601frmt: 0x02 chkval: 0x96a9 type: 0x06=trans data


SQL> select HLADDR ,NAME,a.DBABLK, GETS,MISSES,IMMEDIATE_GETS imm_get,2 IMMEDIATE_MISSES imm_miss,SPIN_GETS,SLEEP1 from x$bh a,v$latch_children b3* where a.hladdr = b.addr and DBARFIL=29 order by 3 ;

HLADDR NAME DBABLK GETS MISSES IMM_GET IMM_MISS SPIN_GETS SLEEP1--------- -------------------------- ---- ------ ------- ------- --------- ------

0D44DC9A8 cache buffers chains 2 1884 0 81 0 0 00D47FD418 cache buffers chains 11 1776 0 84 0 0 00D47FD418 cache buffers chains 11 1776 0 84 0 0 00D45DD590 cache buffers chains 12 1791 0 85 0 0 00D43BD708 cache buffers chains 13 1915 0 84 0 0 00D472D880 cache buffers chains 14 2008 0 85 0 0 00D450D9F8 cache buffers chains 15 1893 0 82 0 0 00D487DB70 cache buffers chains 16 1893 0 82 0 0 0

8 rows selected.



0D44DC9A8 cache buffers chains 2 1884 0 81 0 0 00D47FD418 cache buffers chains 11 1776 0 84 0 0 00D47FD418 cache buffers chains 11 1776 0 84 0 0 00D45DD590 cache buffers chains 12 1791 0 85 0 0 00D43BD708 cache buffers chains 13 1915 0 84 0 0 00D472D880 cache buffers chains 14 2008 0 85 0 0 00D450D9F8 cache buffers chains 15 1893 0 82 0 0 00D487DB70 cache buffers chains 16 1893 0 82 0 0 0

8 rows selected.

v$latch_children

Latch Waits

cache buffers chains

SQL> create index idxtest1 on TEST1(ID) tablespace buffertest;

SQL>SELECT SEGMENT_NAME,HEADER_FILE,HEADER_BLOCK,BYTES,BLOCKS,EXTENTS FROM DBA_SEGMENTS WHERE SEGMENT_NAME LIKE 'IDXTEST1'


IDXTEST1 29 19 65536 8 1

SQL>SELECT SEGMENT_NAME,HEADER_FILE,HEADER_BLOCK,BYTES,BLOCKS,EXTENTS FROM DBA_SEGMENTS WHERE SEGMENT_NAME LIKE 'IDXTEST1'


IDXTEST1 29 19 65536 8 1

Index creation

SQL> select object_id,object_name from dba_objects where object_name='IDXTEST1';OBJECT_ID OBJECT_NAME

---------- --------------

18092 IDXTEST1

SQL> select * from test1 where id=100;

Execution Plan----------------------------------------------------------


----------------------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 1 | 11 | 2 (0)| 00:00:01 || 1 | TABLE ACCESS BY INDEX ROWID| TEST1 | 1 | 11 | 2 (0)| 00:00:01 ||* 2 | INDEX RANGE SCAN | IDXTEST1 | 1 | | 1 (0)| 00:00:01 |----------------------------------------------------------------------------------------


Execution Plan----------------------------------------------------------


----------------------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 1 | 11 | 2 (0)| 00:00:01 || 1 | TABLE ACCESS BY INDEX ROWID| TEST1 | 1 | 11 | 2 (0)| 00:00:01 ||* 2 | INDEX RANGE SCAN | IDXTEST1 | 1 | | 1 (0)| 00:00:01 |----------------------------------------------------------------------------------------


ID DESC1---------- ----------

100 BUFFER1

Explain Plan

SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode(state,0,'free',1,'xcur',2,'scur',3,'cr', 4,'read',5,'mrec',6,'irec',7,'write',8,'pi') state from x$bh whereDBARFIL=29 order by 2 ;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STATE---------- -------- ------- --------- --------- --------- -----

0D44DC9A8 2 29 0A0488000 0D44DCBE0 0D44DCBE0 xcur0D43BD708 13 29 09FA00000 0D43BD880 0D43BD880 xcur0D458DE88 20 29 09F638000 0D458E040 0D458E040 xcur

SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode(state,0,'free',1,'xcur',2,'scur',3,'cr', 4,'read',5,'mrec',6,'irec',7,'write',8,'pi') state from x$bh whereDBARFIL=29 order by 2 ;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STATE---------- -------- ------- --------- --------- --------- -----

0D44DC9A8 2 29 0A0488000 0D44DCBE0 0D44DCBE0 xcur0D43BD708 13 29 09FA00000 0D43BD880 0D43BD880 xcur0D458DE88 20 29 09F638000 0D458E040 0D458E040 xcur

INDEX

DataSegmentheader

L1BMB

L2BMB

191817 20 21 22 23 242File SpaceHeader

64k ( 8 blocks )

X$BH

CHAIN: 69528 LOC: 0xd44dcbe0 HEAD: [a0f9c858,a0f9c858]BH (0xa0f9c858) file#: 29 rdba: 0x07400002 (29/2) class: 13 ba: 0xa0488000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 23dbwrid: 0 obj: -1 objn: 1 tsn: 28 afn: 29hash: [d44dcbe0,d44dcbe0] lru: [a0f9c9e8,a0f9c7c8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [cf3a9348,cf3a9348]st: XCURRENT md: NULL tch: 2flags: gotten_in_current_modeLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.004110b0 seq: 0x02 flg: 0x04 tail: 0x10b01d02frmt: 0x02 chkval: 0x4393 type: 0x1d=KTFB Bitmapped File Space Header

CHAIN: 69528 LOC: 0xd44dcbe0 HEAD: [a0f9c858,a0f9c858]BH (0xa0f9c858) file#: 29 rdba: 0x07400002 (29/2) class: 13 ba: 0xa0488000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 23dbwrid: 0 obj: -1 objn: 1 tsn: 28 afn: 29hash: [d44dcbe0,d44dcbe0] lru: [a0f9c9e8,a0f9c7c8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [cf3a9348,cf3a9348]st: XCURRENT md: NULL tch: 2flags: gotten_in_current_modeLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.004110b0 seq: 0x02 flg: 0x04 tail: 0x10b01d02frmt: 0x02 chkval: 0x4393 type: 0x1d=KTFB Bitmapped File Space Header

CHAIN: 16652 LOC: 0xd43bd880 HEAD: [9ffcb018,9ffcb018]BH (0x9ffcb018) file#: 29 rdba: 0x0740000d (29/13) class: 1 ba: 0x9fa00000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 23dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d43bd880,d43bd880] lru: [9ffcb1a8,9ffcaf88]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0fc8b0,ce0fc8b0]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x03 flg: 0x06 tail: 0xabab0603frmt: 0x02 chkval: 0x0c13 type: 0x06=trans data

CHAIN: 16652 LOC: 0xd43bd880 HEAD: [9ffcb018,9ffcb018]BH (0x9ffcb018) file#: 29 rdba: 0x0740000d (29/13) class: 1 ba: 0x9fa00000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 23dbwrid: 0 obj: 17918 objn: 17918 tsn: 28 afn: 29hash: [d43bd880,d43bd880] lru: [9ffcb1a8,9ffcaf88]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0fc8b0,ce0fc8b0]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.003fabab seq: 0x03 flg: 0x06 tail: 0xabab0603frmt: 0x02 chkval: 0x0c13 type: 0x06=trans data


CHAIN: 102160 LOC: 0xd458e040 HEAD: [9ffaadd8,9ffaadd8]BH (0x9ffaadd8) file#: 29 rdba: 0x07400014 (29/20) class: 1 ba: 0x9f638000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 19dbwrid: 1 obj: 18092 objn: 18092 tsn: 28 afn: 29hash: [d458e040,d458e040] lru: [9ffab078,9ffaad48]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0f3548,ce0f3548]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.004110b8 seq: 0x01 flg: 0x04 tail: 0x10b80601frmt: 0x02 chkval: 0x1176 type: 0x06=trans data

CHAIN: 102160 LOC: 0xd458e040 HEAD: [9ffaadd8,9ffaadd8]BH (0x9ffaadd8) file#: 29 rdba: 0x07400014 (29/20) class: 1 ba: 0x9f638000set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 19dbwrid: 1 obj: 18092 objn: 18092 tsn: 28 afn: 29hash: [d458e040,d458e040] lru: [9ffab078,9ffaad48]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq: [ce0f3548,ce0f3548]st: XCURRENT md: NULL tch: 1flags:LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]scn: 0x0000.004110b8 seq: 0x01 flg: 0x04 tail: 0x10b80601frmt: 0x02 chkval: 0x1176 type: 0x06=trans data




0D44DC9A8 cache buffers chains 2 198 0 45 0 0 00D43BD708 cache buffers chains 13 196 0 44 0 0 00D458DE88 cache buffers chains 20 197 0 44 0 0 0

3 rows selected.



0D44DC9A8 cache buffers chains 2 198 0 45 0 0 00D43BD708 cache buffers chains 13 196 0 44 0 0 00D458DE88 cache buffers chains 20 197 0 44 0 0 0

3 rows selected.

Latch Waits

cache buffers chains

v$latch_children

Touch countTouch count

SQL> select addr,HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode (state,0,'free',1,'xcur',2,'scur',3,'cr','read',5,'mrec',6,'irec',7,'write',8,'pi') state,tch,tim2* from x$bh where DBARFIL=29 order by 3

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- --- ------- --------- --------- --------- ---- ---- ----------

0D44DC9A8 2 29 0A0488000 0D44DCBE0 0D44DCBE0 xcur 2 12837303900D43BD708 13 29 09FA00000 0D43BD880 0D43BD880 xcur 1 12837303900D458DE88 20 29 09F638000 0D458E040 0D458E040 xcur 1 1283730390

SQL> select addr,HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode (state,0,'free',1,'xcur',2,'scur',3,'cr','read',5,'mrec',6,'irec',7,'write',8,'pi') state,tch,tim2* from x$bh where DBARFIL=29 order by 3

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- --- ------- --------- --------- --------- ---- ---- ----------

0D44DC9A8 2 29 0A0488000 0D44DCBE0 0D44DCBE0 xcur 2 12837303900D43BD708 13 29 09FA00000 0D43BD880 0D43BD880 xcur 1 12837303900D458DE88 20 29 09F638000 0D458E040 0D458E040 xcur 1 1283730390

Touch count

09:10:22 SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode (state,0,'free',1,'xcur',2,'scur',3,'cr','read',5,'mrec' ,6,'irec',7,'write',8,'pi') state,tch,tim from x$bh where DBARFIL=29 order by 3 ;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- ------ ------- --------- --------- --------- ---- --- ----------

0D44DC9A8 2 29 0A0488000 0D44DCBE0 09DF7AC98 xcur 2 12837303900D43BD708 13 29 09FA00000 0D43BD880 0D43BD880 xcur 4 12837894220D458DE88 20 29 09F638000 0D458E040 0D458E040 xcur 4 1283789422

09:10:42 SQL> select * from test1 where ID=100;

ID DESC1---------- ----------

100 BUFFER1

09:11:01 SQL> HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- ------ ------- --------- --------- --------- ---- --- ----------


09:11:02 SQL>

09:10:22 SQL> select HLADDR,DBABLK,DBARFIL ,ba,NXT_HASH, PRV_HASH ,decode (state,0,'free',1,'xcur',2,'scur',3,'cr','read',5,'mrec' ,6,'irec',7,'write',8,'pi') state,tch,tim from x$bh where DBARFIL=29 order by 3 ;

HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- ------ ------- --------- --------- --------- ---- --- ----------


09:10:42 SQL> select * from test1 where ID=100;

ID DESC1---------- ----------

100 BUFFER1

09:11:01 SQL> HLADDR DBABLK DBARFIL BA NXT_HASH PRV_HASH STAT TCH TIM--------- ------ ------- --------- --------- --------- ---- --- ----------


09:11:02 SQL>

Touch count

Direct memory Direct memory updateupdate

BH BH

BH

0

1Latch #

PROCESS #1

n BH

Hash table Hash chain Buffer cache

8 K

BH

Direct memory update

SQL >

SQL> create table blkinmemory (id number,desc2 varchar2(10)) tablespace TBLSIZE;

Table created.

SQL> insert into blkinmemory VALUES(546,'BUFFER1');

1 row created.

SQL> COMMIT;

Commit complete.

SQL> create table blkinmemory (id number,desc2 varchar2(10)) tablespace TBLSIZE;

Table created.

SQL> insert into blkinmemory VALUES(546,'BUFFER1');

1 row created.

SQL> COMMIT;

Commit complete.



CHAIN: 251736 LOC: 0xd48ba850 HEAD: [9ffcc668,9ffcc668]BH (0x9ffcc668) file#: 16 rdba: 0x04000008 (16/8)

class: 1 ba: 0x9fa2a000set: 9 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 191dbwrid: 0 obj: 18427 objn: 18427 tsn: 15 afn: 16hash: [d48ba850,d48ba850] lru: [9ffcc908,9ffcc5d8]lru-flags: debug_dumpckptq: [NULL] fileq: [NULL] objq:

[ce0e30b0,ce0e30b0]st: XCURRENT md: NULL tch: 2flags: only_sequential_access

BH BH

BH

0

251736Latch #

PROCESS #1

n BH

Hash table Hash chain Buffer cache

0x09FA27FF0

0x09fa2a000

2F06C203

8 K

ba: 0x9fa2a000


3806c2032F06C203

dump( 546,16), dump( 555,16)

SQL >

0x9ffcc668

updated

0x09FA27FF0

0x09fa2a0008 K

3806c203

DBWR

disk

6:20:45 SQL> select * from blkinmemory;

ID DESC2---------- ----------

546 BUFFER1

Elapsed: 00:00:00.00

16:21:09 SQL> ORADEBUG SETMYPIDStatement processed.16:21:14 SQL> oradebug peek 0x09FA27FF0 4[09FA27FF0, 09FA27FF4) = 2F06C20316:21:20 SQL> oradebug poke 0x09FA27FF0 4 0x3806c203BEFORE: [09FA27FF0, 09FA27FF4) = 2F06C203AFTER: [09FA27FF0, 09FA27FF4) = 3806C20316:21:27 SQL> select * from blkinmemory;

ID DESC2---------- ----------

555 BUFFER1

Elapsed: 00:00:00.0016:21:34 SQL>


Total System Global Area 1979711488 bytesFixed Size 2085000 bytesVariable Size 889196408 bytesDatabase Buffers 1073741824 bytesRedo Buffers 14688256 bytesDatabase mounted.Database opened.SQL> set time on16:24:14 SQL> set timing on16:24:18 SQL> select * from blkinmemory;

ID DESC2---------- ----------

546 BUFFER1

Elapsed: 00:00:00.0016:24:27 SQL>

Total System Global Area 1979711488 bytesFixed Size 2085000 bytesVariable Size 889196408 bytesDatabase Buffers 1073741824 bytesRedo Buffers 14688256 bytesDatabase mounted.Database opened.SQL> set time on16:24:14 SQL> set timing on16:24:18 SQL> select * from blkinmemory;

ID DESC2---------- ----------

546 BUFFER1

Elapsed: 00:00:00.0016:24:27 SQL>


Oracle wait Events

cache buffers chains cache buffers lru chain buffer busy waits free buffer waits read by other session db file single block read db file sequential read

cache buffers chains cache buffers lru chain buffer busy waits free buffer waits read by other session db file single block read db file sequential read

BH BH BH

BH BH BH

0

1

Latch # 1

PROCESS #1

PROCESS #2

PROCESS #3


MAIN

AUX

Hot End Cold EndLRU List

LRU # 1Free Blocks

Midpoint Insertion

DBWR

disk

Redobuffer

Shared pool

Black Box

Buffer cache

DBWR

Disk

DBWRDBWR

Localtion of Block Box

ARCH LGWR

Disk

CKPT

PMON SMON

SGA

SGA Internal ASM Internal RDS concept EXADATA concept RMAN Internal Control file Internal LMT Internal

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