[ODI] chapter3 What is Max CR DBA(Max length)?

Oracle Deep Internal report no. 003

What is Max CR DBA(Max length)?

(_db_block_max_cr_dba=6 )

Research & Contents Team

What is Max CR DBA(Max length)?(_db_block_max_cr_dba=6 )03

Lee Kun Oh ()

Kwon Kon Woo ()

Buffer Cache

Scenario

XCURRENTcol 1: [ 1] 41 (A)

BH (0x657d8238)

BA

C

D

EF

G

H

I

Update; Commit

Up

dat

e; C

om

mit

BCDEFGHI

When update a value A with values B to I consecutively, How are cu blocks and cr blocks allocated inside the Buffer Cache?

Buffer Cache

CURRENT BLOCK(XCUR)

Update

S1

Consistent ReadBlock(CR 1)& UNDO

Update

S2


Update

S3


Update

S4


Update

S5


Update

S6

Expected outcome

2013, Oracle 10g Performance: chapter 06 buffer cache 25,26 page, Kyle Hailey

It's so difficult to understand only through the book.I'd like to check internal actual situation of oracle

with my own eyes

Cited from http://www.slideshare.net/khailey/oracle-10g-performance-chapter-06-buffer-cache

Max length in Cache Buffermechanism as explained in Kyle Hailey's presentation

1. UPDATE T1 SET C2='B' ; COMMIT ; 2. UPDATE T1 SET C2=C' ; COMMIT ; 3. UPDATE T1 SET C2= D' ; COMMIT ;. . . . . . . . . . . . . 9. UPDATE T1 SET C2=G' ; COMMIT ; . . . . .. . . ?

5/18/2016

Buffer Cache

CRcol 1: [ 1] 41 (A)

BH (0x657d8238)

CRcol 1: [ 1] 42 (B)

BH (0x657d8100)

CRcol 1: [ 1] 43 (C)

BH (0x653fab88)

CRcol 1: [ 1] 44 (D)

BH (0x653fa7e0)

CRcol 1: [ 1] 45 (E)

BH (0x653fa438)

CRcol 1: [ 1] 46 (F)

BH (0x653fa090)

New CU block

New CU block

New CU Block

XCURRENT

XCURRENTXCURRENT

XCURRENT

XCURRENT

New CU Block

XCURRENTcol 1: [ 1] 48 (H)

XCURRENTcol 1: [ 1] 49 (I)

XCURRENT

CR Block Reuse

XCURRENTcol 1: [ 1] 47 (G)

Inside of Oracle via ODI tool When _db_block_max_cr_dba = 6

CR Block Reuse

CRcol 1: [ 1] 47 (G)

CRcol 1: [ 1] 48 (H)

block1

block2

block3

block4

block5

block6

block1

block2

block3

Oracle init parameterWhen _db_block_max_cr_dba = 6

New CU blockCR Block Reuse

Undo Segment

Data Block

Buffer Cache

1. UPDATE T1 SET C2='B' ; COMMIT ;

Rowsblock_row_dump:tab 0, row 0, @0x1f70tl: 16 fb: --H-FL-- lb: 0x0 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 41 A

BH (0x657d8100) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x65438000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0027.000.000000c4 0x00000000.0000.00 C--- 0 scn 0x0000.0021a1100x02 0x0025.000.00000138 0x018000a2.009b.01 ---- 1 fsc 0x0000.000000000x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x2 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 42

BH (0x657d8238) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x6543a000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0027.000.000000c4 0x00000000.0000.00 C--- 0 scn 0x0000.0021a1100x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.000000000x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x0 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 41

1

BH (0x657d7e90) file#: 6 rdba: 0x018000a2(6/162) class: 90 ba: 0x65434000xid: 0x0025.000.00000138 seq: 0x9b* Rec #0x1 slt: 0x00 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 41

2

A

B

A

UPDATE T1 SET c2 = B

Undo Segment

Data Block

Buffer Cache

2. UPDATE SYSTEM.T1 SET C2=C' ; COMMIT ;

Rowsblock_row_dump:tab 0, row 0, @0x1f70tl: 16 fb: --H-FL-- lb: 0x0 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 41




1

A A

BH (0x653fa918) file#: 6 rdba: 0x01800092(6/146) class: 86 ba: 0x653c2000xid: 0x0023.000.00000132 seq: 0xa2 * Rec #0x1 slt: 0x00 objn: 69880(0x000110f8) * Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 42

B

UPDATE T1 SET c2 = C

BH (0x657d8100) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x65438000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


2

B

BH (0x653fab88) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653c6000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0027.000.000000c4 0x00000000.0000.00 C--- 0 scn 0x0000.0021a1100x02 0x0025.000.00000138 0x018000a2.009b.01 C--- 0 scn 0x0000.0021a11e0x03 0x0023.000.00000132 0x01800092.00a2.01 ---- 1 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 43

3

C

st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Undo Segment

Data Block

Buffer Cache

3. UPDATE SYSTEM.T1 SET C2=D' ; COMMIT ;






BH (0x657d8100) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x65438000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


21

A A

BH (0x653fa7e0) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653c0000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 ---- 1 fsc 0x0000.000000000x02 0x0025.000.00000138 0x018000a2.009b.01 C--- 0 scn 0x0000.0021a11e0x03 0x0023.000.00000132 0x01800092.00a2.01 C--- 0 scn 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x1 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 44

4

D

BH (0x653fa570) file#: 6 rdba: 0x01800082(6/130) class: 18 ba: 0x653bc000xid: 0x0001.000.000009ef seq: 0x352 * Rec #0x1 slt: 0x00 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 43 C

B

UPDATE T1 SET c2 = D


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0027.000.000000c4 0x00000000.0000.00 C--- 0 scn 0x0000.0021a1100x02 0x0025.000.00000138 0x018000a2.009b.01 C--- 0 scn 0x0000.0021a11e0x03 0x0023.000.00000132 0x01800092.00a2.01 --U- 1 fsc 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 43

3

C


Undo Segment

Data Block

Buffer Cache

BH (0x653fa438) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653ba000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 C--- 0 scn 0x0000.0021a1240x02 0x002c.001.000000c4 0x01800112.0069.11 ---- 1 fsc 0x0000.000000000x03 0x0023.000.00000132 0x01800092.00a2.01 C--- 0 scn 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x2 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 45

5

E

4. UPDATE SYSTEM.T1 SET C2=E' ; COMMIT ;




BH (0x653fa570) file#: 6 rdba: 0x01800082(6/130) class: 18 ba: 0x653bc000xid: 0x0001.000.000009ef seq: 0x352 * Rec #0x1 slt: 0x00 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 43





BH (0x653fab88) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653c6000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


21

3

BH (0x653fa1c8) file#: 6 rdba: 0x01800112(6/274) class: 104 ba: 0x653b6000xid: 0x002c.001.000000c4 seq: 0x69* Rec #0x11 slt: 0x01 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 44 D

BC

BH (0x653fa7e0) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653c0000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 --U- 1 fsc 0x0000.0021a1240x02 0x0025.000.00000138 0x018000a2.009b.01 C--- 0 scn 0x0000.0021a11e0x03 0x0023.000.00000132 0x01800092.00a2.01 C--- 0 scn 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x1 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 44

4

D

UPDATE T1 SET c2 = E


Undo Segment

Data Block

Buffer Cache

5. UPDATE SYSTEM.T1 SET C2=F' ; COMMIT ;





BH (0x653fa1c8) file#: 6 rdba: 0x01800112(6/274) class: 104 ba: 0x653b6000xid: 0x002c.001.000000c4 seq: 0x69* Rec #0x11 slt: 0x01 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 44

BH (0x653fa7e0) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653c0000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1








21

3

4

AA

BH (0x653fa090) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653b4000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 C--- 0 scn 0x0000.0021a1240x02 0x002c.001.000000c4 0x01800112.0069.11 C--- 0 scn 0x0000.0021a1270x03 0x002b.001.000000c6 0x01800102.0062.02 ---- 1 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 46

6

F BH (0x653f9e20) file#: 6 rdba: 0x01800102(6/258) class: 102 ba: 0x653b0000xid: 0x002b.001.000000c6 seq: 0x62 * Rec #0x2 slt: 0x01 objn: 69880(0x000110f8) * Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 45 E

BC

D

UPDATE T1 SET c2 = F

BH (0x653fa438) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653ba000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 C--- 0 scn 0x0000.0021a1240x02 0x002c.001.000000c4 0x01800112.0069.11 --U- 1 fsc 0x0000.0021a1270x03 0x0023.000.00000132 0x01800092.00a2.01 C--- 0 scn 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x2 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 45

5

E


Undo Segment

Data Block

Buffer Cache

6. UPDATE SYSTEM.T1 SET C2=G' ; COMMIT ; Reuse BH 8283






BH (0x653f9e20) file#: 6 rdba: 0x01800102(6/258) class: 102 ba: 0x653b0000xid: 0x002b.001.000000c6 seq: 0x62 * Rec #0x2 slt: 0x01 objn: 69880(0x000110f8) * Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 45





BH (0x653fa438) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653ba000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


21

3

4

5

A A

BH (0x653f9bb0) file#: 6 rdba: 0x018000f2(6/242) class: 100 ba: 0x653ac000xid: 0x002a.001.000000c6 seq: 0x62 * Rec #0x3 slt: 0x01 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 46

F

DE

UPDATE T1 SET c2 = G


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 ---- 1 fsc 0x0000.000000000x02 0x002c.001.000000c4 0x01800112.0069.11 C--- 0 scn 0x0000.0021a1270x03 0x002b.001.000000c6 0x01800102.0062.02 C--- 0 scn 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x1 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 41

1

A

BH (0x653fa090) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653b4000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0001.000.000009ef 0x01800082.0352.01 C--- 0 scn 0x0000.0021a1240x02 0x002c.001.000000c4 0x01800112.0069.11 C--- 0 scn 0x0000.0021a1270x03 0x002b.001.000000c6 0x01800102.0062.02 --U- 1 fsc 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 46

6

F


st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

47 G





BC

Undo Segment

Data Block

Buffer Cache

7. UPDATE SYSTEM.T1 SET C2=H' ; COMMIT ; Reuse BH 8100















BH (0x653fa090) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653b4000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


21

3

4

5

6

A A

DE

F


BH (0x653f9940) file#: 6 rdba: 0x018000e2(6/226) class: 98 ba: 0x653a8000xid: 0x0029.001.00000107 seq: 0xbc* Rec #0x4 slt: 0x01 objn: 69880(0x000110f8) * Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 47 G

1

BH (0x657d8238) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x6543a000st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 --U- 1 fsc 0x0000.0021a12d0x02 0x002c.001.000000c4 0x01800112.0069.11 C--- 0 scn 0x0000.0021a1270x03 0x002b.001.000000c6 0x01800102.0062.02 C--- 0 scn 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x1 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 47 G


UPDATE T1 SET c2 = H


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 C--- 0 scn 0x0000.0021a12d0x02 0x0029.001.00000107 0x018000e2.00bc.04 ---- 1 fsc 0x0000.000000000x03 0x002b.001.000000c6 0x01800102.0062.02 C--- 0 scn 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x2 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 42

2


48 BH


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x0027.000.000000c4 0x00000000.0000.00 C--- 0 scn 0x0000.0021a1100x02 0x0025.000.00000138 0x018000a2.009b.01 C--- 0 scn 0x0000.0021a11e0x03 0x0023.000.00000132 0x01800092.00a2.01 --U- 1 fsc 0x0000.0021a121tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 43 C

Undo Segment

Data Block

Buffer Cache

8. UPDATE SYSTEM.T1 SET C2=I' ; COMMIT ; Reuse BHab88








BH (0x653f9940) file#: 6 rdba: 0x018000e2(6/226) class: 98 ba: 0x653a8000xid: 0x0029.001.00000107 seq: 0xbc* Rec #0x4 slt: 0x01 objn: 69880(0x000110f8) * Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 47











BH (0x653fa090) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x653b4000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1


21

3

4

5

6 BH (0x657d8238) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x6543a000st: CR md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 --U- 1 fsc 0x0000.0021a12d0x02 0x002c.001.000000c4 0x01800112.0069.11 C--- 0 scn 0x0000.0021a1270x03 0x002b.001.000000c6 0x01800102.0062.02 C--- 0 scn 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x1 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 47

1

A AB

DE

FG

UPDATE T1 SET c2 = I


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 C--- 0 scn 0x0000.0021a12d0x02 0x0029.001.00000107 0x018000e2.00bc.04 C--- 0 scn 0x0000.0021a1300x03 0x0028.004.000000db 0x018000d3.00b2.08 ---- 1 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 43

3

BH (0x653f96d0) file#: 6 rdba: 0x018000d3(6/211) class: 96 ba: 0x653a4000xid: 0x0028.004.000000db seq: 0xb2* Rec #0x8 slt: 0x04 objn: 69880(0x000110f8)* Layer: 11 (Row) opc: 1 rci 0x00col 1: [ 1] 48

H

BH (0x657d8100) file#: 5 rdba: 0x0140dcab (5/56491) class: 1 ba: 0x65438000sst: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1

Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 C--- 0 scn 0x0000.0021a12d0x02 0x0029.001.00000107 0x018000e2.00bc.04 --U- 1 fsc 0x0000.0021a1300x03 0x002b.001.000000c6 0x01800102.0062.02 C--- 0 scn 0x0000.0021a12atl: 16 fb: --H-FL-- lb: 0x2 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 48

2

H


Itl Xid Uba Flag Lck Scn/Fsc0x01 0x002a.001.000000c6 0x018000f2.0062.03 C--- 0 scn 0x0000.0021a12d0x02 0x0029.001.00000107 0x018000e2.00bc.04 C--- 0 scn 0x0000.0021a1300x03 0x0028.004.000000db 0x018000d3.00b2.08 ---- 1 fsc 0x0000.00000000tl: 16 fb: --H-FL-- lb: 0x3 cc: 2col 0: [10] 31 20 20 20 20 20 20 20 20 20col 1: [ 1] 43

3



C49 I

5/18/2016

Buffer Cache

CRcol 1: [ 1] 41 (A)

BH (0x657d8238)

CRcol 1: [ 1] 42 (B)

BH (0x657d8100)

CRcol 1: [ 1] 43 (C)

BH (0x653fab88)

CRcol 1: [ 1] 44 (D)

BH (0x653fa7e0)

CRcol 1: [ 1] 45 (E)

BH (0x653fa438)

CRcol 1: [ 1] 46 (F)

BH (0x653fa090)

New CU block

New CU block

New CU Block

XCURRENT

XCURRENTXCURRENT

XCURRENT

XCURRENT

New CU Block

XCURRENTcol 1: [ 1] 48 (H)

XCURRENTcol 1: [ 1] 49 (I)

XCURRENT

CR Block Reuse

XCURRENTcol 1: [ 1] 47 (G)

Inside of Oracle via ODI tool When _db_block_max_cr_dba = 6

CR Block Reuse

CRcol 1: [ 1] 47 (G)

CRcol 1: [ 1] 48 (H)

block1

block2

block3

block4

block5

block6

block1

block2

block3

Oracle init parameter _db_block_max_cr_dba=6

When _db_block_max_cr_dba equals 6, a maximum of 6 data blocks are allocated and rotate among them for updates.

New CU blockCR Block Reuse

Oracle Deep Internal

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[ODI] chapter3 What is Max CR DBA(Max length)?