初探oracle open初始化過程，初探oracle
[oracle@localhost ~]$ lsb_release -a
LSB Version: :core-3.1-ia32:core-3.1-noarch:graphics-3.1-ia32:graphics-3.1-noarch
Distributor ID: EnterpriseEnterpriseServer
Description: Enterprise Linux Enterprise Linux Server release 5.5 (Carthage)
Release: 5.5
Codename: Carthage
SQL> select * from v$version where rownum < 2;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
SQL> startup mount;
ORACLE 例程已經啟動。
SQL> alter session set sql_trace = true;
會話已更改。
SQL> alter database open;
數據庫已更改。
SQL> select * from v$diag_info where NAME='Default Trace File';
INST_ID NAME
---------- ----------------------------------------------------------------
VALUE
--------------------------------------------------------------------------------
1 Default Trace File
/u01/app/oracle/diag/rdbms/orcl3939/orcl3939/trace/orcl3939_ora_14443.trc
11g提供了v$diag_info,通過查詢V$diag_info可以很容易找到自身服務進程的trace文件位置。
當然由oracle生成trace文件的特性：
SQL> select distinct sid from v$mystat;
SID
----------
9
SQL> select paddr from v$session where sid=9;
PADDR
--------
34FC8DAC
SQL> select spid from v$process where addr='34FC8DAC';
SPID
------------------------
14443
也很快在茫茫的trace文件中找到我們想要的文件。
*** 2015-04-26 00:28:20.034
*** SESSION ID:(9.3) 2015-04-26 00:28:20.034
*** CLIENT ID:() 2015-04-26 00:28:20.034
*** SERVICE NAME:() 2015-04-26 00:28:20.034
*** MODULE NAME:(
[email protected] (TNS V1-V3)) 2015-04-26 00:28:20.034
*** ACTION NAME:() 2015-04-26 00:28:20.034
=====================
PARSING IN CURSOR #1 len=34 dep=0 uid=0 oct=42 lid=0 tim=1429979299982435 hv=2069488880 ad='73fed0' sqlid='1hgzr5xxpmt7h'
alter session set sql_trace = true
END OF STMT
EXEC #1:c=0,e=143,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=0,tim=1429979299933691
*** 2015-04-26 00:28:44.514
CLOSE #1:c=0,e=12,dep=0,type=0,tim=1429979324514259
*** 2015-04-26 00:28:44.516
XCTEND rlbk=0, rd_only=1, tim=1429979324516325
=====================
PARSING IN CURSOR #1 len=19 dep=0 uid=0 oct=35 lid=0 tim=1429979324552260 hv=1907384048 ad='349dcfe4' sqlid='a01hp0psv0rrh'
alter database open
END OF STMT
PARSE #1:c=3999,e=36299,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=0,tim=1429979324552257
=====================
PARSING IN CURSOR #2 len=188 dep=1 uid=0 oct=1 lid=0 tim=1429979324829034 hv=4006182593 ad='349db650' sqlid='32r4f1brckzq1'
create table bootstrap$ ( line# number not null, obj# number not null, sql_text varchar2(4000) not null) storage (initial 50K objno 59 extents (file 1 block 520))
END OF STMT
PARSE #2:c=1000,e=926,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,plh=0,tim=1429979324829031
EXEC #2:c=0,e=378,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,plh=0,tim=1429979324829510
CLOSE #2:c=0,e=9,dep=1,type=0,tim=1429979324829642
=====================
PARSING IN CURSOR #2 len=55 dep=1 uid=0 oct=3 lid=0 tim=1429979324830543 hv=2111436465 ad='349da4f8' sqlid='6apq2rjyxmxpj'
select line#, sql_text from bootstrap$ where obj# != :1
END OF STMT
PARSE #2:c=999,e=878,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,plh=0,tim=1429979324830540
EXEC #2:c=3000,e=59167,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,plh=867914364,tim=1429979324889837
FETCH #2:c=1000,e=1299,p=4,cr=3,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891270
FETCH #2:c=0,e=21,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891377
FETCH #2:c=1000,e=329,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891738
FETCH #2:c=0,e=17,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891814
FETCH #2:c=0,e=9,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891852
FETCH #2:c=0,e=9,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891886
FETCH #2:c=0,e=31,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891942
FETCH #2:c=0,e=12,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324891992
..........
..........
FETCH #2:c=0,e=9,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324897158
FETCH #2:c=0,e=8,p=0,cr=1,cu=0,mis=0,r=1,dep=1,og=4,plh=867914364,tim=1429979324897190
FETCH #2:c=0,e=8,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,plh=867914364,tim=1429979324897222
STAT #2 id=1 cnt=59 pid=0 pos=1 obj=59 op='TABLE ACCESS FULL BOOTSTRAP$ (cr=61 pr=4 pw=0 time=0 us)'
CLOSE #2:c=0,e=30,dep=1,type=0,tim=1429979324927299
CREATE INDEX I_UNDO2 ON UNDO$(NAME) PCTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE ( INITIAL 64K NEXT 1024K MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 OBJNO 35 EXTENTS (FILE 1 BLOCK 328))
END OF STMT
PARSE #2:c=999,e=961,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,plh=4258903948,tim=1429979324980690
EXEC #2:c=0,e=315,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,plh=4258903948,tim=1429979324981087
STAT #2 id=1 cnt=0 pid=0 pos=1 obj=0 op='INDEX BUILD NON UNIQUE I_UNDO2 (cr=0 pr=0 pw=0 time=0 us)'
STAT #2 id=2 cnt=0 pid=1 pos=1 obj=0 op='SORT CREATE INDEX (cr=0 pr=0 pw=0 time=0 us cost=0 size=0 card=0)'
STAT #2 id=3 cnt=0 pid=2 pos=1 obj=15 op='TABLE ACCESS FULL UNDO$ (cr=0 pr=0 pw=0 time=0 us)'
CLOSE #2:c=0,e=7,dep=1,type=0,tim=1429979324981283
=====================
PARSING IN CURSOR #2 len=208 dep=1 uid=0 oct=9 lid=0 tim=1429979324983049 hv=246520463 ad='349c51f8' sqlid='18806807b36ng'
CREATE UNIQUE INDEX I_OBJ1 ON OBJ$(OBJ#,OWNER#,TYPE#) PCTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE ( INITIAL 64K NEXT 1024K MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 OBJNO 36 EXTENTS (FILE 1 BLOCK 336))
END OF STMT
=====================
..............
..............
上面顏色部分可以由sql_id對應執行的sql語句。
紅色部分創建了表bootstrap$,這個表在1號文件的第520個塊上，看這是什麼表空間：
SQL> select * from dba_data_files where file_id=1;
FILE_NAME FILE_ID TABLESPACE_NAME BYTES BLOCKS STATUS RELATIVE_FNO AUT MAXBYTES MAXBLOCKS INCREMENT_BY USER_BYTES USER_BLOCKS ONLINE_
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------- ------------------------------ ---------- ---------- --------- ------------ --- ---------- ---------- ------------ ---------- ----------- -------
/u01/app/oracle/oradata/orcl3939/system01.dbf 1 SYSTEM 786432000 96000 AVAILABLE 1 YES 3.4360E+10 4194302 1280 785383424 95872 SYSTEM
分析它的表結構：
bootstrap$ ( line# number not null, obj# number not null, sql_text varchar2(4000) not null)
裡面放的有對象編號，以及sql語句，通過查找bootstrap$:
SQL> select * from bootstrap$ where rownum<=3;
LINE# OBJ# SQL_TEXT
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-1 -1 8.0.0.0.0
0 0 CREATE ROLLBACK SEGMENT SYSTEM STORAGE ( INITIAL 112K NEXT 56K MINEXTENTS 1 MAXEXTENTS 32765 OBJNO 0 EXTENTS (FILE 1 BLOCK 128))
20 20 CREATE TABLE ICOL$("OBJ#" NUMBER NOT NULL,"BO#" NUMBER NOT NULL,"COL#" NUMBER NOT NULL,"POS#" NUMBER NOT NULL,"SEGCOL#" NUMBER NOT NULL,"SEGCOLLENGTH" NUMBER NOT NULL,"OFFSET" NUMBER NOT NULL,"INTCOL#" NUMBER NOT NULL,"SPARE1" NUMBER,"SPARE2" NUMBER,"SPARE3" NUMBER,"SPARE4" VARCHAR2(1000),"SPARE5" VARCHAR2(1000),"SPARE6" DATE) STORAGE ( OBJNO 20 TABNO 4) CLUSTER C_OBJ#(BO#)
由上述trace文件可知,創建boostrap$之後，又創建：
CREATE ROLLBACK SEGMENT SYSTEM STORAGE ( INITIAL 112K NEXT 56K MINEXTENTS 1 MAXEXTENTS 32765 OBJNO 0 EXTENTS (FILE 1 BLOCK 128))
CREATE TABLE TS$("TS#" NUMBER NOT NULL,"NAME" VARCHAR2(30) NOT NULL,"OWNER#" NUMBER NOT NULL,"ONLINE$" NUMBER NOT NULL,"CONTENTS$" NUMBER NOT NULL,"UNDOFILE#" NUMBER,"UNDOBLOCK#" NUMBER,"BLOCKSIZE" NUMBER NOT NULL,"INC#" NUMBER NOT NULL,"SCNWRP" NUMBER,"SCNBAS" NUMBER,"DFLMINEXT" NUMBER NOT NULL,"DFLMAXEXT" NUMBER NOT NULL,"DFLINIT" NUMBER NOT NULL,"DFLINCR" NUMBER NOT NULL,"DFLMINLEN" NUMBER NOT NULL,"DFLEXTPCT" NUMBER NOT NULL,"DFLOGGING" NUMBER NOT NULL,"AFFSTRENGTH" NUMBER NOT NULL,"BITMAPPED" NUMBER NOT NULL,"PLUGGED" NUMBER NOT NULL,"DIRECTALLOWED" NUMBER NOT NULL,"FLAGS" NUMBER NOT NULL,"PITRSCNWRP" NUMBER,"PITRSCNBAS" NUMBER,"OWNERINSTANCE" VARCHAR2(30),"BACKUPOWNER" VARCHAR2(30),"GROUPNAME" VARCHAR2(30),"SPARE1" NUMBER,"SPARE2" NUMBER,"SPARE3" VARCHAR2(1000),"SPARE4" DATE) STORAGE ( OBJNO 16 TABNO 2) CLUSTER C_TS#(TS#)
CREATE TABLE FILE$("FILE#" NUMBER NOT NULL,"STATUS$" NUMBER NOT NULL,"BLOCKS" NUMBER NOT NULL,"TS#" NUMBER,"RELFILE#" NUMBER,"MAXEXTEND" NUMBER,"INC" NUMBER,"CRSCNWRP" NUMBER,"CRSCNBAS" NUMBER,"OWNERINSTANCE" VARCHAR2(30),"SPARE1" NUMBER,"SPARE2" NUMBER,"SPARE3" VARCHAR2(1000),"SPARE4" DATE) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 STORAGE ( INITIAL 64K NEXT 1024K MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 OBJNO 17 EXTENTS (FILE 1 BLOCK 232))
CREATE TABLE OBJ$("OBJ#" NUMBER NOT NULL,"DATAOBJ#" NUMBER,"OWNER#" NUMBER NOT NULL,"NAME" VARCHAR2(30) NOT NULL,"NAMESPACE" NUMBER NOT NULL,"SUBNAME" VARCHAR2(30),"TYPE#" NUMBER NOT NULL,"CTIME" DATE NOT NULL,"MTIME" DATE NOT NULL,"STIME" DATE NOT NULL,"STATUS" NUMBER NOT NULL,"REMOTEOWNER" VARCHAR2(30),"LINKNAME" VARCHAR2(128),"FLAGS" NUMBER,"OID$" RAW(16),"SPARE1" NUMBER,"SPARE2" NUMBER,"SPARE3" NUMBER,"SPARE4" VARCHAR2(1000),"SPARE5" VARCHAR2(1000),"SPARE6" DATE) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 STORAGE ( INITIAL 16K NEXT 104K MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 OBJNO 18 EXTENTS (FILE 1 BLOCK 240))
.........
.........
那數據文件1中的第520個塊之前的塊是哪些呢？
通過下面sql語句，可以看到頭塊為520之前的塊的對象:
SQL>
select b.object_id,a.segment_name,a.segment_type,a.header_block from dba_segments a,dba_objects b where
a.segment_name=b.object_name(+) and a.header_file=1 and a.header_block<=520 order by a.header_block;SQL> 2
/
OBJECT_ID SEGMENT_NAME SEGMENT_TYPE HEADER_BLOCK
---------- --------------------------------------------------------------------------------- ------------------ ------------
SYSTEM ROLLBACK 128
2 C_OBJ# CLUSTER 144
3 I_OBJ# INDEX 168
6 C_TS# CLUSTER 176
7 I_TS# INDEX 184
8 C_FILE#_BLOCK# CLUSTER 192
9 I_FILE#_BLOCK# INDEX 200
10 C_USER# CLUSTER 208
11 I_USER# INDEX 216
15 UNDO$ TABLE 224
17 FILE$ TABLE 232
18 OBJ$ TABLE 240
23 PROXY_DATA$ TABLE 248
24 I_PROXY_DATA$ INDEX 256
25 PROXY_ROLE_DATA$ TABLE 264
26 I_PROXY_ROLE_DATA$_1 INDEX 272
27 I_PROXY_ROLE_DATA$_2 INDEX 280
28 CON$ TABLE 288
29 C_COBJ# CLUSTER 296
30 I_COBJ# INDEX 304
33 I_TAB1 INDEX 312
34 I_UNDO1 INDEX 320
35 I_UNDO2 INDEX 328
36 I_OBJ1 INDEX 336
37 I_OBJ2 INDEX 344
38 I_OBJ3 INDEX 352
39 I_OBJ4 INDEX 360
40 I_OBJ5 INDEX 368
41 I_IND1 INDEX 376
42 I_ICOL1 INDEX 384
43 I_FILE1 INDEX 392
44 I_FILE2 INDEX 400
45 I_TS1 INDEX 408
46 I_USER1 INDEX 416
47 I_USER2 INDEX 424
48 I_COL1 INDEX 432
49 I_COL2 INDEX 440
50 I_COL3 INDEX 448
51 I_CON1 INDEX 456
52 I_CON2 INDEX 464
53 I_CDEF1 INDEX 472
54 I_CDEF2 INDEX 480
55 I_CDEF3 INDEX 488
56 I_CDEF4 INDEX 496
57 I_CCOL1 INDEX 504
58 I_CCOL2 INDEX 512
59 BOOTSTRAP$ TABLE 520
已選擇47行。
由trace文件知道(也可以直接查bootstrap$)，520之前塊正是與數據庫啟動相關的塊!
結合trace文件和bootstrap$可知，先加載bootstrap$後，由sql_text然後遞歸創建oracle啟動所需的對象。
那1號文件第520個塊了到底放些什麼呢？
學會使用trace對於研究數據庫很重要：
SQL> alter system dump datafile 1 block 520;
系統已更改。
以下摘自部分trace文件：
*** 2015-04-26 01:05:26.707
CLOSE #23:c=0,e=110,dep=0,type=0,tim=1429981526707493
=====================
PARSE ERROR #12:len=35 dep=0 uid=0 oct=49 lid=0 tim=1429981526715635 err=25117
alter system dump datafile 1 block
=====================
declare
m_stmt varchar2(512);
begin
m_stmt:='delete from sdo_geor_ddl__table$$';
EXECUTE IMMEDIATE m_stmt;
EXCEPTION
WHEN OTHERS THEN
NULL;
end;
=====================
select obj#,type#,ctime,mtime,stime, status, dataobj#, flags, oid$, spare1, spare2 from obj$ where owner#=:1 and name=:2 and namespace=:3 and remoteowner is null and linkname is null and subname is null
....
select t.ts#,t.file#,t.block#,nvl(t.bobj#,0),nvl(t.tab#,0),t.intcols,nvl(t.clucols,0),t.audit$,t.flags,t.pctfree$,t.pctused$,t.initrans,t.maxtrans,t.rowcnt,t.blkcnt,t.empcnt,t.avgspc,t.chncnt,t.avgrln,t.analyzetime,t.samplesize,t.cols,t.property,nvl(t.degree,1),nvl(t.instances,1),t.avgspc_flb,t.flbcnt,t.kernelcols,nvl(t.trigflag, 0),nvl(t.spare1,0),nvl(t.spare2,0),t.spare4,t.spare6,ts.cachedblk,ts.cachehit,ts.logicalread from tab$ t, tab_stats$ ts where t.obj#= :1 and t.obj# = ts.obj# (+)
....
select i.obj#,i.ts#,i.file#,i.block#,i.intcols,i.type#,i.flags,i.property,i.pctfree$,i.initrans,i.maxtrans,i.blevel,i.leafcnt,i.distkey,i.lblkkey,i.dblkkey,i.clufac,i.cols,i.analyzetime,i.samplesize,i.dataobj#,nvl(i.degree,1),nvl(i.instances,1),i.rowcnt,mod(i.pctthres$,256),i.indmethod#,i.trunccnt,nvl(c.unicols,0),nvl(c.deferrable#+c.valid#,0),nvl(i.spare1,i.intcols),i.spare4,i.spare2,i.spare6,decode(i.pctthres$,null,null,mod(trunc(i.pctthres$/256),256)),ist.cachedblk,ist.cachehit,ist.logicalread from ind$ i, ind_stats$ ist, (select enabled, min(cols) unicols,min(to_number(bitand(defer,1))) deferrable#,min(to_number(bitand(defer,4))) valid# from cdef$ where obj#=:1 and enabled > 1 group by enabled) c where i.obj#=c.enabled(+) and i.obj# = ist.obj#(+) and i.bo#=:1 order by i.obj#
....
select name,intcol#,segcol#,type#,length,nvl(precision#,0),decode(type#,2,nvl(scale,-127/*MAXSB1MINAL*/),178,scale,179,scale,180,scale,181,scale,182,scale,183,scale,231,scale,0),null$,fixedstorage,nvl(deflength,0),default$,rowid,col#,property, nvl(charsetid,0),nvl(charsetform,0),spare1,spare2,nvl(spare3,0) from col$ where obj#=:1 order by intcol#
....
select con#,obj#,rcon#,enabled,nvl(defer,0),spare2,spare3 from cdef$ where robj#=:1
....
select con#,type#,condlength,intcols,robj#,rcon#,match#,refact,nvl(enabled,0),rowid,cols,nvl(defer,0),mtime,nvl(spare1,0),spare2,spare3 from cdef$ where obj#=:1
....
select decode(u.type#, 2, u.ext_username, u.name), o.name, t.update$, t.insert$, t.delete$, t.enabled, decode(bitand(t.property, 8192),8192, 1, 0), decode(bitand(t.property, 65536), 65536, 1, 0), decode(bitand(t.property, 131072), 131072, 1, 0), (select o.name from obj$ o where o.obj# = u.spare2 and o.type# =57) from sys.obj$ o, sys.user$ u, sys.trigger$ t, sys.obj$ bo where t.baseobject=bo.obj# and bo.name = :1 and bo.spare3 = :2 and bo.namespace = 1 and t.obj#=o.obj# and o.owner#=u.user# and o.type# = 12 and bitand(property,16)=0 and bitand(property,8)=0 order by o.obj#
....
select col#, grantee#, privilege#,max(mod(nvl(option$,0),2)) from objauth$ where obj#=:1 and col# is not null group by privilege#, col#, grantee# order by col#, grantee#
....
select grantee#,privilege#,nvl(col#,0),max(mod(nvl(option$,0),2))from objauth$ where obj#=:1 group by grantee#,privilege#,nvl(col#,0) order by grantee#
m sdo_geor_ddl__table$$
*** 2015-04-26 01:05:40.179
CLOSE #12:c=0,e=20,dep=0,type=0,tim=1429981540179940
=====================
PARSING IN CURSOR #36 len=38 dep=0 uid=0 oct=49 lid=0 tim=1429981540180608 hv=4117028914 ad='0' sqlid='07605w7uq9s1k'
alter system dump datafile 1 block 520
END OF STMT
PARSE #36:c=1000,e=484,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=0,plh=0,tim=1429981540180606
Start dump data blocks tsn: 0 file#:1 minblk 520 maxblk 520
Block dump from cache:
Dump of buffer cache at level 4 for tsn=0, rdba=4194824
BH (0x28fe7134) file#: 1 rdba: 0x00400208 (1/520) class: 4 ba: 0x28cc6000
set: 5 pool 3 bsz: 8192 bsi: 0 sflg: 1 pwc: 0,28
dbwrid: 0 obj: 59 objn: 59 tsn: 0 afn: 1 hint: f
hash: [0x33e8e55c,0x33e8e55c] lru: [0x297ec8d4,0x28fe72b4]
lru-flags: on_auxiliary_list
ckptq: [NULL] fileq: [NULL] objq: [0x31ff2434,0x28fe72cc]
st: XCURRENT md: NULL tch: 1
flags:
LRBA: [0x0.0.0] LSCN: [0x0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]
cr pin refcnt: 0 sh pin refcnt: 0
Block dump from disk:
*** 2015-04-26 01:05:40.454
buffer tsn: 0 rdba: 0x00400208 (1/520)
scn: 0x0000.00000251 seq: 0x01 flg: 0x04 tail: 0x02511001
frmt: 0x02 chkval: 0xe443 type: 0x10=DATA SEGMENT HEADER - UNLIMITED
Hex dump of block: st=0, typ_found=1
Dump of memory from 0x00772000 to 0x00774000
......
......
Extent Control Header
-----------------------------------------------------------------
Extent Header:: spare1: 0 spare2: 0 #extents: 1 #blocks: 7
last map 0x00000000 #maps: 0 offset: 4128
Highwater:: 0x0040020c ext#: 0 blk#: 3 ext size: 7
#blocks in seg. hdr's freelists: 1
#blocks below: 3
mapblk 0x00000000 offset: 0
Unlocked
Map Header:: next 0x00000000 #extents: 1 obj#: 59 flag: 0x40000000
Extent Map
-----------------------------------------------------------------
0x00400209 length: 7
nfl = 1, nfb = 1 typ = 1 nxf = 0 ccnt = 3
SEG LST:: flg: USED lhd: 0x0040020b ltl: 0x0040020b
End dump data blocks tsn: 0 file#: 1 minblk 520 maxblk 520
下面是部分sql語句：
select timestamp, flags from fixed_obj$ where obj#=:1
SELECT inst_id, name, value FROM x$diag_info
SELECT inst_id, name, value FROM gv$diag_info WHERE inst_id = USERENV('INSTANCE')
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select * from v$diag_info where NAME='Default Trace File'
select timestamp, flags from fixed_obj$ where obj#=:1
select timestamp, flags from fixed_obj$ where obj#=:1
select timestamp, flags from fixed_obj$ where obj#=:1
select inst_id,ksusenum,ksusestn,ksusestv from x$ksumysta where bitand(ksspaflg,1)!=0 and bitand(ksuseflg,1)!=0 and ksusestn<(select ksusgstl from x$ksusgif)
select SID , STATISTIC# , VALUE from GV$MYSTAT where inst_id = USERENV('Instance')
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select * from v$mystat
select distinct sid from v$mystat
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select paddr from v$session where sid=9
select timestamp, flags from fixed_obj$ where obj#=:1
select addr, pid, spid, pname, username, serial#, terminal, program, traceid, tracefile, background, latchwait,latchspin,pga_used_mem,pga_alloc_mem,pga_freeable_mem,pga_max_mem from gv$process where inst_id = USERENV('Instance')
select /*+ rule */ bucket_cnt, row_cnt, cache_cnt, null_cnt, timestamp#, sample_size, minimum, maximum, distcnt, lowval, hival, density, col#, spare1, spare2, avgcln from hist_head$ where obj#=:1 and intcol#=:2
select spid from v$process where addr='34FC8DAC'
......
......
分析上述標記的紅色字體段：
BH (0x28fe7134) file#: 1 rdba: 0x00400208 (1/520)
BH(0x28fe7134):記錄的是該塊在buffer cache中實際的內存地址(buffer header)
rdba:root dba
(1/520):猜想是指bootstrapt$,下面來驗證
後面的OX00400208是十六進制數：
先轉換成二進制數：
0 0 4 0 0 2 0 8
0000 0000 0100 0000 0000 0010 0000 1000
由前面的文章知，前十位表示文件編號：
0000000001：1
後22位表示塊號：
0000000000001000001000：16*16*2 + 8=520
上述也可以用oracle提供的包直接來計算。
rdba指向的bootstrap$！
原來數據庫的引導過程中，rdba用來定位數據庫引導的bootstrap$信息。
上面說了這麼多，那bootstrap$又是如何創建的呢？
通過蓋國強老師的《深入解析Oralce》得知，原來在創建數據庫的腳本裡，oracle會隱含的調用/u01/app/oracle/product/11.2.0/dbhome_1/rdbms/admin/sql.bsq 用於創建數據字典，如果oracle找不到sql.bsq腳本，數據庫創建會出錯。我們可以通過修改sql.bsq腳本來更改數據字典對象參數，從而實現特殊要求數據庫的創建或測試的自定義庫。
下面摘自部分sql.bsq文本：
rem
rem $Header: rdbms/admin/sql.bsq /main/606 2008/07/14 17:25:59 vliang Exp $ sql.bsq
rem MODIFIED
rem huagli 06/09/08 - add ddst.bsq
rem dvoss 01/03/07 - add dlmnr.bsq
rem rdecker 10/20/06 - create SYSAUX before running dplsql.bsq
rem jklein 08/01/05 - diag 11g - split-up into units
rem sdavidso 08/01/05 - add tranform_param type check info
rem mmpandey 06/07/05 - 4390808: increase the cache value in audses$
rem mvemulap 05/02/05 - bug fix for 4318925
rem mhho 04/20/05 - change colklc column size in enc$
rem tfyu 02/28/05 - Bug 4262763
rem htran 03/11/05 - remove transportable from fgr$_tablespace_info
rem mmcracke 03/14/05 - add ddm.bsq for data mining models
rem alakshmi 02/28/05 - error recovery for maintain_ apis
rem ddas 01/07/05 - #(4052436) add hint_string to ol$hints
rem sourghos 01/06/05 - Fix bug 4043119
rem ilyubash 11/05/04 - Add gen column to i_aw_prop$ index
rem elu 01/03/05 - streams apply spilling
rem htran 11/15/04 - comments for spare1 in user$ and streams$_prepare_*
rem apadmana 10/05/04 - bug3607838: manage any queue
rem clei 04/15/04 - add view merge permission
rem weiwang 10/14/04 - set queue flag in base view
rem mtakahar 09/03/04 - create mon_mods_all$
rem clei 09/01/04 - add comments to encryption property flags
rem xuhuali 03/31/04 - audit java
rem kdias 07/15/04 - revisit privs granted to OUTLN user
rem nmanappa 07/20/04 - bug 3690876 - clean privileges 194-199,239,240
rem dmwong 07/21/04 - fix connect role to only contain create session
rem skaluska 07/09/04 - split up tsm_hist$ into tsm_src$, tsm_dest$
rem araghava 07/07/04 - (3748430): make partitioning indexes unique.
rem clei 06/29/04 - add enc$
rem ssvemuri 06/25/04 - change notification privilege
rem ramkrish 06/16/04 - correct model nmspc and type
rem nshodhan 06/11/04 - use streams$_capture_process.spare3
.....
.....
rem varora 04/28/95 - rename col#,usercol#,cols,usercols
rem tcheng 03/21/95 - add col# to adtcol$ and ntab$
rem varora 01/27/95 - add table for nested table support
rem skotsovo 01/25/95 - bring normalized type tables up to date
rem skotsovo 01/23/95 - move exceptions from method to method_body
rem jwijaya 01/04/95 - add system privileges for type
rem jwijaya 12/29/94 - making type$ work (temporarily allow 'version'
rem 'checks' columns nullable and mark 'checks'
rem and 'default$' not-supported (N/S))
rem skrishna 12/06/94 - create extent table of pre-defined types
rem varora 12/01/94 - change toid in adtcol$ to type number
rem anori 11/17/94 - ADT support tables and columns
rem
rem !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! IMPORTANT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
rem Whenever new column is created to store internal, user or kernel column
rem number, be sure to update the structure adtDT in atb.c so that those
rem columns will be updated properly during drop column.
rem !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
rem
dcore.bsq
dsqlddl.bsq
dmanage.bsq
dplsql.bsq
dtxnspc.bsq
dfmap.bsq
denv.bsq
drac.bsq
dsec.bsq
doptim.bsq
dobj.bsq
djava.bsq
dpart.bsq
drep.bsq
daw.bsq
dsummgt.bsq
dtools.bsq
dexttab.bsq
ddm.bsq
dlmnr.bsq
ddst.bsq
SYSTEM表空間的重要性可想而知，如果system表空間損壞，則數據庫無法打開。SYSTEM表空間的備份重於一切。
oracle啟動初始化過程十分復雜,上面的很多東西都值得我們去研究，鑒於本人水平有限，希望讀者在此基礎上對oracle啟動初始化過程有更深次的理解。
