数据块（4）— Row Directory

 

我们先回顾一下 Row Directory 中的信息：

 

-- Row Directory

data_block_dump,data header at 0x3051074

===============

tsiz: 0x1f88

hsiz: 0x22

pbl: 0x03051074

bdba: 0x02c000e2

     76543210

flag=--------

ntab=1

nrow=8

frre=-1

fsbo=0x22

fseo=0x1ec0

avsp=0x1f1e

tosp=0x1f1e

0xe:pti[0] nrow=8 offs=0

0x12:pri[0]   offs=0x1eff

0x14:pri[1]   offs=0x1ef6

0x16:pri[2]   offs=0x1eed

0x18:pri[3]   offs=0x1ee4

0x1a:pri[4]   offs=0x1edb

0x1c:pri[5]   offs=0x1ed2

0x1e:pri[6]   offs=0x1ec9

0x20:pri[7]   offs=0x1ec0

 

tsiz: total data area size

hsiz: data header size

pbl: point to buffer holding the block

bdba: rdba，与 Header 中的 rdba 相同。

flag：n=pctfree hit(clusters); f=do not put on freelist;k=flushable cluster keys

ntab：number of tables (>1 in clusters)

nrow：number of rows

frre：first free row index entry;-1=you have to add one

fsbo：free space begin offset

fseo：free space end offset

avsp：available space in the block

tosp：total available space when all txs commit

 

 

（参考的DATA BLOCK内部结构）