oracle--块信息深入解析

一,创建

　　Data Block是数据库中最小的I/O单元

　　01,建立一个新的表空间

　　查看默认表空间位置

select TABLESPACE_NAME,FILE_NAME from dba_data_files;

　　创建一个表空间放其他的地方把

create tablespace test2 datafile  '/orcl/app/table/test2.dbf' size 20m reuse autoextend on next 20m maxsize UNLIMITED extent management local;

　　02,创建用户

查看CDB

select name,cdb from v$database;

查看pDb

SQL> select pdb_id,pdb_name,dbid,status,creation_scn from dba_pdbs;

    PDB_ID PDB_NAME DBID STATUS      CREATION_SCN
---------- -----------------------------------------------------------------------------------
     3 ORCLPDB   3877422513 NORMAL           1442756
     2 PDB$SEED   4118313826 NORMAL           1408751
     4 HRPDB   1506437541 NORMAL           4081006
     5 SALESPDB   1453096304 NORMAL           4087331

查看PDB状态

SQL> select con_id,dbid,NAME,OPEN_MODE from v$pdbs;

    CON_ID     DBID NAME      OPEN_MODE
---------- ---------- -----------------------------------------------------
     2 4118313826 PDB$SEED      READ ONLY
     3 3877422513 ORCLPDB      READ WRITE
     4 1506437541 HRPDB      READ ONLY
     5 1453096304 SALESPDB      READ ONLY

创建使用者为test

SQL> create user c##test identified by test;

User created.

切换PDB
SQL>  show con_name;

CON_NAME
------------------------------
CDB$ROOT
SQL> alter session set container=ORCLPDB;

Session altered.

SQL> show con_name;

CON_NAME
------------------------------
ORCLPDB
创建表空间
SQL> create tablespace test2 datafile '/orcl/app/table/test2.dbf' size 20M;

Tablespace created.

创建真正的用户

SQL> create user test identified by test default tablespace test2;

User created.
授予权限
SQL> grant dba to test

Grant succeeded.

　　03,建立数据

SQL> create table t1 (id int,name varchar2(100));

Table created.

SQL> insert into t1 values(1,'A');

1 row created.

SQL> alter system checkpoint;

System altered.

SQL> col name for a10
SQL> select  id,name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block# from t1;

    ID NAME        FILE#     BLOCK#
---------- ---------- ---------- ----------
     1 A               1      32641

SQL> select p.spid from v$session s,v$process p where s.paddr=p.addr and s.sid in (select userenv('sid') from dual);

SPID
------------------------
17124

SQL>  alter system dump datafile 1 block 32641;

System altered.

SQL> select p.spid from v$session s,v$process p where s.paddr=p.addr and s.sid in (select userenv('sid') from dual);

SPID
------------------------
17124

SQL> select p.spid from v$session s,v$process p where s.paddr=p.addr and s.sid in (select userenv('sid') from dual);

SPID
------------------------
17124

SQL> select object_id from dba_objects where object_name='T1' and owner='SYS';

 OBJECT_ID
----------
     75798

[oracle@node12c01 trace]$ more orcl_ora_20178.trc
Trace file /orcl/app/oracle/diag/rdbms/node12c01/orcl/trace/orcl_ora_20178.trc
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
Build label:    RDBMS_12.2.0.1.0_LINUX.X64_170125
ORACLE_HOME:    /orcl/app/oracle/product/12.1.0/db_1
System name:    Linux
Node name:    node12c01
Release:    3.10.0-693.el7.x86_64
Version:    #1 SMP Tue Aug 22 21:09:27 UTC 2017
Machine:    x86_64
Instance name: orcl
Redo thread mounted by this instance: 1
Oracle process number: 36
Unix process pid: 20178, image: oracle@node12c01 (TNS V1-V3)


*** 2019-04-16T05:29:55.899559-04:00 (CDB$ROOT(1))
*** SESSION ID:(31.49582) 2019-04-16T05:29:55.899596-04:00
*** CLIENT ID:() 2019-04-16T05:29:55.899601-04:00
*** SERVICE NAME:(SYS$USERS) 2019-04-16T05:29:55.899605-04:00
*** MODULE NAME:(sqlplus@node12c01 (TNS V1-V3)) 2019-04-16T05:29:55.899610-04:00
*** ACTION NAME:() 2019-04-16T05:29:55.899614-04:00
*** CLIENT DRIVER:(SQL*PLUS) 2019-04-16T05:29:55.899617-04:00
*** CONTAINER ID:(1) 2019-04-16T05:29:55.899621-04:00

Start dump data blocks tsn: 0 file#:1 minblk 32641 maxblk 32641
Block dump from cache:
Dump of buffer cache at level 4 for pdb=1 tsn=0 rdba=4226945
Block dump from disk:
buffer tsn: 0 rdba: 0x00407f81 (1/32641)
scn: 0x5d140 seq: 0x01 flg: 0x06 tail: 0xd1400601
frmt: 0x02 chkval: 0x6c32 type: 0x06=trans data
Hex dump of block: st=0, typ_found=1
Dump of memory from 0x00007FBF65C6A000 to 0x00007FBF65C6C000

分析:

数据头:
buffer tsn: 0 rdba: 0x00419578 (1/103800)
scn: 0x4ea6cf seq: 0x02 flg: 0x04 tail: 0xa6cf1002 frmt: 0x02 chkval: 0x5692 type: 0x10=DATA SEGMENT HEADER - UNLIMITED

flg：0x01 (新建块)0x2(数据块延迟清洗推进scn和seq) 0X04(设置校验和) 0x08(临时块)
type：0x06(表/索引块)
frmt:  0x01(v7)  0x02(v8)

Hex dump of block: st=0, typ_found=1
Dump of memory from 0x00007F12ACAA4000 to 0x00007F12ACAA6000
7F12ACAA4000 0000A210 00419578 004EA6CF 04020000  [....x.A...N.....]
7F12ACAA4010 00005692 00000000 00000000 00000000  [.V..............]
7F12ACAA4020 00000000 00000001 00000007 00001020  [............ ...]
7F12ACAA4030 00000000 00000003 00000007 0041957C  [............|.A.]
7F12ACAA4040 00000000 00000000 00000001 00000003  [................]
7F12ACAA4050 00000000 00000000 00000000 00000001  [................]
7F12ACAA4060 00000000 000125D4 40000000 00419579  [.....%.....@y.A.]
7F12ACAA4070 00000007 00000000 00000000 00000000  [................]
7F12ACAA4080 00000000 00000000 00000000 00000000  [................]
        Repeat 250 times
7F12ACAA5030 00000000 00010000 00010001 00000001  [................]
7F12ACAA5040 00000000 00000003 0041957B 0041957B  [........{.A.{.A.]
7F12ACAA5050 00000000 00000000 00000000 00000000  [................]
        Repeat 249 times
7F12ACAA5FF0 00000000 00000000 00000000 A6CF1002  [................]

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