Sundaramurthy Blog

February 13, 2010

Inside data block

Filed under: Oracle Block,Oracle internals — sundar5 @ 12:08 am

Block:

Below is the data block dump and see the details on the bottom of the page.

buffer tsn: 4 rdba: 0×010001b8 (4/440)
scn: 0×0000.000a3982 seq: 0×02 flg: 0×00 tail: 0×39820602
frmt: 0×02 chkval: 0×0000 type: 0×06=trans dataBlock header dump:  0×010001b8
Object id on Block? Y
seg/obj: 0xcd60  csc: 0×00.a37e1  itc: 2  flg: E  typ: 1 – DATA
brn: 0  bdba: 0×10001b1 ver: 0×01 opc: 0
inc: 0  exflg: 0Itl     Xid                            Uba     Flag  Lck        Scn/Fsc
0×01   0×0007.018.00000172  0×0080025b.013c.0c  —-    1  fsc 0×0000.00000000
0×02   0×0000.000.00000000  0×00000000.0000.00  —-    0  fsc 0×0000.00000000
data_block_dump,data header at 0xd5b6664
===============
tsiz: 0×1f98
hsiz: 0×14
pbl: 0×0d5b6664
bdba: 0×010001b8
76543210
flag=——–
ntab=1
nrow=1
frre=-1
fsbo=0×14fseo=0×1f8a
avsp=0×1f76
tosp=0×1f76
0xe:pti[0]    nrow=1    offs=0
0×12:pri[0]    offs=0×1f8a
block_row_dump:
tab 0, row 0, @0×1f8a
tl: 14 fb: –H-FL– lb: 0×1  cc: 2
col  0: [ 2]  c1 02
col  1: [ 7]  53 55 4e 44 41 52 31

Legend:

scn: scn number last changed this block.
seq: number of Changes within the block.

seg/obj: table name or object id test02
itc: number of itl allocated (2)

Itl : Intersting transaction list
Xid : Undo header Transaction id (0x0007.018.00000172)

0x0007 : undo segment #
018 : Trasnsaction #
00000172: Slot #

Uba : Undo data block (0x0080025b.013c.0c)

0x0080025b : undo File block #
013c : Sequance #
0c : record #

Flags:
—- = Transaction is active
C— = Transaction has been committed and locks cleaned
-B– = This undo record contains the undo for this ITL entry
–U- = Transaction committed (maybe long ago) delayed blcok cleanout not occure.
—T = Transaction was still active at block cleanout SCN

Lck    Row locks(1 record locked so far current ITL)

scn/Fsc

Free space credit/system changes number
tsiz : Total size ( 8088 bytes )
hsiz : Header size (14 bytes)
pbl  : pointer block in the buffer cache
bdba : database block address

ntab=1       number of table (For cluster table it will be more than 1)
nrow=1       number of rows in the block.
frre=-1      First free row idnex entry
fsbo=0x14    Free space begining offset
fseo=0x1f8a  Free space end offset
avsp=0x1f76  Average block space in bytes
tosp=0x1f76  Space available in post commit.

0xe:pti[0]   nrow=1    offs=0   Table details
0x12:pri[0]  offs=0x1f8a    row information offset (first row start 0)

tab 0        data for table 0
row 0        number of record in the block (0 mean 1 record)
@0x1f8a      the record is starting offset number from  0x1f8a
tl           Total bytes of the record + header info = 14
fb           Block bytes (KCHDFLPN)
K=Cluster key
C=Cluster table member
H=Header of row piece
D=Delete flag
F=First data piece
L=Last piece
P= First column continue from privious piece chaining
N=Last column continue from next piece.
lb           Lock bytes( 0 is unlocked 1 locked)
cc           Column count 2


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