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oracle数据库的数据字典视图，数据来自哪个（些）表？

Oracle数据库有4大类系统“表“：

内部表
数据字典表
动态视图
数据字典视图

常用的，诸如DBA_**, ALL_**, USER_**，都是数据字典视图！

1. 以DBA_TABLES为例，来看看这个视图从哪些”表”里获取了数据？

  1 SQL>
  2 SQL>
  3 SQL> select text from dba_views where view_name like 'DBA_TABLES';
  4 
  5 TEXT
  6 --------------------------------------------------------------------------------
  7 select u.name, o.name,
  8 decode(bitand(t.property,2151678048), 0, ts.name,
  9 decode(t.ts#, 0, null, ts.name)),
 10 decode(bitand(t.property, 1024), 0, null, co.name),
 11 decode((bitand(t.property, 512)+bitand(t.flags, 536870912)),
 12 0, null, co.name),
 13 decode(bitand(t.trigflag, 1073741824), 1073741824, 'UNUSABLE', 'VALID'),
 14 decode(bitand(t.property, 32+64), 0, mod(t.pctfree$, 100), 64, 0, null),
 15 decode(bitand(ts.flags, 32), 32, to_number(NULL),
 16 decode(bitand(t.property, 32+64), 0, t.pctused$, 64, 0, null)),
 17 decode(bitand(t.property, 32), 0, t.initrans, null),
 18 
 19 TEXT
 20 --------------------------------------------------------------------------------
 21 decode(bitand(t.property, 32), 0, t.maxtrans, null),
 22 decode(bitand(t.property, 17179869184), 17179869184,
 23 ds.initial_stg * ts.blocksize,
 24 s.iniexts * ts.blocksize),
 25 decode(bitand(t.property, 17179869184), 17179869184,
 26 ds.next_stg * ts.blocksize,
 27 s.extsize * ts.blocksize),
 28 decode(bitand(t
 29 
 30 
 31 SQL> set long 2048;
 32 SQL>
 33 SQL>
 34 SQL> select text from dba_views where view_name like 'DBA_TABLES';
 35 
 36 TEXT
 37 --------------------------------------------------------------------------------
 38 select u.name, o.name,
 39 decode(bitand(t.property,2151678048), 0, ts.name,
 40 decode(t.ts#, 0, null, ts.name)),
 41 decode(bitand(t.property, 1024), 0, null, co.name),
 42 decode((bitand(t.property, 512)+bitand(t.flags, 536870912)),
 43 0, null, co.name),
 44 decode(bitand(t.trigflag, 1073741824), 1073741824, 'UNUSABLE', 'VALID'),
 45 decode(bitand(t.property, 32+64), 0, mod(t.pctfree$, 100), 64, 0, null),
 46 decode(bitand(ts.flags, 32), 32, to_number(NULL),
 47 decode(bitand(t.property, 32+64), 0, t.pctused$, 64, 0, null)),
 48 decode(bitand(t.property, 32), 0, t.initrans, null),
 49 
 50 TEXT
 51 --------------------------------------------------------------------------------
 52 decode(bitand(t.property, 32), 0, t.maxtrans, null),
 53 decode(bitand(t.property, 17179869184), 17179869184,
 54 ds.initial_stg * ts.blocksize,
 55 s.iniexts * ts.blocksize),
 56 decode(bitand(t.property, 17179869184), 17179869184,
 57 ds.next_stg * ts.blocksize,
 58 s.extsize * ts.blocksize),
 59 decode(bitand(t.property, 17179869184), 17179869184,
 60 ds.minext_stg, s.minexts),
 61 decode(bitand(t.property, 17179869184), 17179869184,
 62 ds.maxext_stg, s.maxexts),
 63 
 64 TEXT
 65 --------------------------------------------------------------------------------
 66 decode(bitand(ts.flags, 3), 1, to_number(NULL),
 67 decode(bitand(t.property, 17179869184), 17179869184,
 68 ds.pctinc_stg, s.extpct)),
 69 decode(bitand(ts.flags, 32), 32, to_number(NULL),
 70 decode(bitand(o.flags, 2), 2, 1,
 71 decode(bitand(t.property, 17179869184), 17179869184,
 72 ds.frlins_stg, decode(s.lists, 0, 1, s.lists)))),
 73 decode(bitand(ts.flags, 32), 32, to_number(NULL),
 74 decode(bitand(o.flags, 2), 2, 1,
 75 decode(bitand(t.property, 17179869184), 17179869184,
 76 ds.maxins_stg, decode(s.groups, 0, 1, s.groups)))),
 77 
 78 TEXT
 79 --------------------------------------------------------------------------------
 80 decode(bitand(t.property, 32+64), 0,
 81 decode(bitand(t.flags, 32), 0, 'YES', 'NO'), null),
 82 decode(bitand(t.flags,1), 0, 'Y', 1, 'N', '?'),
 83 t.rowcnt,
 84 
 85 
 86 SQL> set long 65535;
 87 SQL>
 88 SQL>
 89 SQL> select text from dba_views where view_name like 'DBA_TABLES';
 90 
 91 TEXT
 92 --------------------------------------------------------------------------------
 93 select u.name, o.name,
 94 decode(bitand(t.property,2151678048), 0, ts.name,
 95 decode(t.ts#, 0, null, ts.name)),
 96 decode(bitand(t.property, 1024), 0, null, co.name),
 97 decode((bitand(t.property, 512)+bitand(t.flags, 536870912)),
 98 0, null, co.name),
 99 decode(bitand(t.trigflag, 1073741824), 1073741824, 'UNUSABLE', 'VALID'),
100 decode(bitand(t.property, 32+64), 0, mod(t.pctfree$, 100), 64, 0, null),
101 decode(bitand(ts.flags, 32), 32, to_number(NULL),
102 decode(bitand(t.property, 32+64), 0, t.pctused$, 64, 0, null)),
103 decode(bitand(t.property, 32), 0, t.initrans, null),
104 
105 TEXT
106 --------------------------------------------------------------------------------
107 decode(bitand(t.property, 32), 0, t.maxtrans, null),
108 decode(bitand(t.property, 17179869184), 17179869184,
109 ds.initial_stg * ts.blocksize,
110 s.iniexts * ts.blocksize),
111 decode(bitand(t.property, 17179869184), 17179869184,
112 ds.next_stg * ts.blocksize,
113 s.extsize * ts.blocksize),
114 decode(bitand(t.property, 17179869184), 17179869184,
115 ds.minext_stg, s.minexts),
116 decode(bitand(t.property, 17179869184), 17179869184,
117 ds.maxext_stg, s.maxexts),
118 
119 TEXT
120 --------------------------------------------------------------------------------
121 decode(bitand(ts.flags, 3), 1, to_number(NULL),
122 decode(bitand(t.property, 17179869184), 17179869184,
123 ds.pctinc_stg, s.extpct)),
124 decode(bitand(ts.flags, 32), 32, to_number(NULL),
125 decode(bitand(o.flags, 2), 2, 1,
126 decode(bitand(t.property, 17179869184), 17179869184,
127 ds.frlins_stg, decode(s.lists, 0, 1, s.lists)))),
128 decode(bitand(ts.flags, 32), 32, to_number(NULL),
129 decode(bitand(o.flags, 2), 2, 1,
130 decode(bitand(t.property, 17179869184), 17179869184,
131 ds.maxins_stg, decode(s.groups, 0, 1, s.groups)))),
132 
133 TEXT
134 --------------------------------------------------------------------------------
135 decode(bitand(t.property, 32+64), 0,
136 decode(bitand(t.flags, 32), 0, 'YES', 'NO'), null),
137 decode(bitand(t.flags,1), 0, 'Y', 1, 'N', '?'),
138 t.rowcnt,
139 decode(bitand(t.property, 64), 0, t.blkcnt, null),
140 decode(bitand(t.property, 64), 0, t.empcnt, null),
141 t.avgspc, t.chncnt, t.avgrln, t.avgspc_flb,
142 decode(bitand(t.property, 64), 0, t.flbcnt, null),
143 lpad(decode(t.degree, 32767, 'DEFAULT', nvl(t.degree,1)),10),
144 lpad(decode(t.instances, 32767, 'DEFAULT', nvl(t.instances,1)),10),
145 lpad(decode(bitand(t.flags, 8), 8, 'Y', 'N'),5),
146 
147 TEXT
148 --------------------------------------------------------------------------------
149 decode(bitand(t.flags, 6), 0, 'ENABLED', 'DISABLED'),
150 t.samplesize, t.analyzetime,
151 decode(bitand(t.property, 32), 32, 'YES', 'NO'),
152 decode(bitand(t.property, 64), 64, 'IOT',
153 decode(bitand(t.property, 512), 512, 'IOT_OVERFLOW',
154 decode(bitand(t.flags, 536870912), 536870912, 'IOT_MAPPING', null
155 ))),
156 decode(bitand(o.flags, 2), 0, 'N', 2, 'Y', 'N'),
157 decode(bitand(o.flags, 16), 0, 'N', 16, 'Y', 'N'),
158 decode(bitand(t.property, 8192), 8192, 'YES',
159 decode(bitand(t.property, 1), 0, 'NO', 'YES')),
160 
161 TEXT
162 --------------------------------------------------------------------------------
163 decode(bitand(o.flags, 2), 2, 'DEFAULT',
164 decode(bitand(decode(bitand(t.property, 17179869184), 17179869184,
165 
166 ds.bfp_stg, s.cachehint), 3),
167 1, 'KEEP', 2, 'RECYCLE', 'DEFAULT')),
168 decode(bitand(o.flags, 2), 2, 'DEFAULT',
169 decode(bitand(decode(bitand(t.property, 17179869184), 17179869184,
170 
171 ds.bfp_stg, s.cachehint), 12)/4,
172 1, 'KEEP', 2, 'NONE', 'DEFAULT')),
173 decode(bitand(o.flags, 2), 2, 'DEFAULT',
174 
175 TEXT
176 --------------------------------------------------------------------------------
177 decode(bitand(decode(bitand(t.property, 17179869184), 17179869184,
178 
179 ds.bfp_stg, s.cachehint), 48)/16,
180 1, 'KEEP', 2, 'NONE', 'DEFAULT')),
181 decode(bitand(t.flags, 131072), 131072, 'ENABLED', 'DISABLED'),
182 decode(bitand(t.flags, 512), 0, 'NO', 'YES'),
183 decode(bitand(t.flags, 256), 0, 'NO', 'YES'),
184 decode(bitand(o.flags, 2), 0, NULL,
185 decode(bitand(t.property, 8388608), 8388608,
186 'SYS$SESSION', 'SYS$TRANSACTION')),
187 decode(bitand(t.flags, 1024), 1024, 'ENABLED', 'DISABLED'),
188 
189 TEXT
190 --------------------------------------------------------------------------------
191 decode(bitand(o.flags, 2), 2, 'NO',
192 decode(bitand(t.property, 2147483648), 2147483648, 'NO',
193 decode(ksppcv.ksppstvl, 'TRUE', 'YES', 'NO'))),
194 decode(bitand(t.property, 1024), 0, null, cu.name),
195 decode(bitand(t.flags, 8388608), 8388608, 'ENABLED', 'DISABLED'),
196 case when (bitand(t.property, 32) = 32) then
197 null
198 when (bitand(t.property, 17179869184) = 17179869184) then
199 decode(bitand(ds.flags_stg, 4), 4, 'ENABLED', 'DISABLED')
200 else
201 decode(bitand(s.spare1, 2048), 2048, 'ENABLED', 'DISABLED')
202 
203 TEXT
204 --------------------------------------------------------------------------------
205 end,
206 case when (bitand(t.property, 32) = 32) then
207 null
208 when (bitand(t.property, 17179869184) = 17179869184) then
209 decode(bitand(ds.flags_stg, 4), 4,
210 case when bitand(ds.cmpflag_stg, 3) = 1 then 'BASIC'
211 when bitand(ds.cmpflag_stg, 3) = 2 then 'OLTP'
212 else decode(ds.cmplvl_stg, 1, 'QUERY LOW',
213 2, 'QUERY HIGH',
214 3, 'ARCHIVE LOW',
215 'ARCHIVE HIGH') end,
216 
217 TEXT
218 --------------------------------------------------------------------------------
219 null)
220 else
221 decode(bitand(s.spare1, 2048), 0, null,
222 case when bitand(s.spare1, 16777216) = 16777216
223 then 'OLTP'
224 when bitand(s.spare1, 100663296) = 33554432 -- 0x2000000
225 then 'QUERY LOW'
226 when bitand(s.spare1, 100663296) = 67108864 -- 0x4000000
227 then 'QUERY HIGH'
228 when bitand(s.spare1, 100663296) = 100663296 -- 0x2000000+0x400000
229 0
230 
231 TEXT
232 --------------------------------------------------------------------------------
233 then 'ARCHIVE LOW'
234 when bitand(s.spare1, 134217728) = 134217728 -- 0x8000000
235 then 'ARCHIVE HIGH'
236 else 'BASIC' end)
237 end,
238 decode(bitand(o.flags, 128), 128, 'YES', 'NO'),
239 decode(bitand(t.trigflag, 2097152), 2097152, 'YES', 'NO'),
240 decode(bitand(t.property, 17179869184), 17179869184, 'NO',
241 decode(bitand(t.property, 32), 32, 'N/A', 'YES')),
242 decode(bitand(t.property,16492674416640),2199023255552,'FORCE',
243 4398046511104,'MANUAL','DEFAULT')
244 
245 TEXT
246 --------------------------------------------------------------------------------
247 from sys.user$ u, sys.ts$ ts, sys.seg$ s, sys.obj$ co, sys.tab$ t, sys.obj$ o,
248 sys.obj$ cx, sys.user$ cu, x$ksppcv ksppcv, x$ksppi ksppi,
249 sys.deferred_stg$ ds
250 where o.owner# = u.user#
251 and o.obj# = t.obj#
252 and bitand(t.property, 1) = 0
253 and bitand(o.flags, 128) = 0
254 and t.bobj# = co.obj# (+)
255 and t.ts# = ts.ts#
256 and t.obj# = ds.obj# (+)
257 and t.file# = s.file# (+)
258 
259 TEXT
260 --------------------------------------------------------------------------------
261 and t.block# = s.block# (+)
262 and t.ts# = s.ts# (+)
263 and t.dataobj# = cx.obj# (+)
264 and cx.owner# = cu.user# (+)
265 and ksppi.indx = ksppcv.indx
266 and ksppi.ksppinm = '_dml_monitoring_enabled'
267 
268 
269 SQL>
270 SQL>

可以知道，DBA_TABLES这个数据字典视图从下面11个“表”获取数据：

sys.user$ u, sys.ts$ ts, sys.seg$ s, sys.obj$ co, sys.tab$ t, sys.obj$ o, sys.obj$ cx, sys.user$ cu, x$ksppcv ksppcv, x$ksppi ksppi, sys.deferred_stg$

其中9个是数据字典表，2个是内部表。

2. 再以动态视图v$process为例，看看动态视图的数据从哪里来？

 1 SQL>
 2 SQL>
 3 SQL> select VIEW_DEFINITION from v$fixed_view_definition where VIEW_NAME = 'V$PROCESS';
 4 
 5 VIEW_DEFINITION
 6 --------------------------------------------------------------------------------
 7 select addr, pid, spid, pname, username, serial#, terminal, program, traceid, tr
 8 acefile, background, latchwait,latchspin,pga_used_mem,pga_alloc_mem,pga_freeable
 9 _mem,pga_max_mem from gv$process where inst_id = USERENV('Instance')
10 
11 
12 SQL> select VIEW_DEFINITION from v$fixed_view_definition where VIEW_NAME = 'GV$PROCESS';
13 
14 VIEW_DEFINITION
15 --------------------------------------------------------------------------------
16 select inst_id, addr, indx, ksuprpid, ksuprpname, ksuprunm, ksuprser, ksuprtid,
17 ksuprpnm, ksuprtfi, ksuprtfn, decode(bitand(ksuprflg,2),0,null,1), decode(ksllaw
18 at,hextoraw('00'),null,ksllawat), decode(ksllaspn,hextoraw('00'),null,ksllaspn),
19  ksuprpum,ksuprpnam+ksuprpram,ksuprpfm, case when ksuprpnam+ksuprpram > ksuprpmm
20        then ksuprpnam+ksuprpram       else ksuprpmm end  from x$ksupr where bita
21 nd(ksspaflg,1)!=0
22 
23 
24 SQL>
25 SQL>

可以知道，视图V$PROCESS的数据来自于视图GV$PROCESS；而GV$PROCESS的数据来自于下面1个表：

x$ksupr

数据库内部表。

 1 SQL>
 2 SQL>
 3 SQL> select VIEW_DEFINITION from v$fixed_view_definition where VIEW_NAME = 'V$DATABASE';
 4 
 5 VIEW_DEFINITION
 6 --------------------------------------------------------------------------------
 7 select  DBID, NAME, CREATED, RESETLOGS_CHANGE#, RESETLOGS_TIME, PRIOR_RESETLOGS_
 8 CHANGE#, PRIOR_RESETLOGS_TIME,LOG_MODE, CHECKPOINT_CHANGE#, ARCHIVE_CHANGE#, CON
 9 TROLFILE_TYPE, CONTROLFILE_CREATED, CONTROLFILE_SEQUENCE#, CONTROLFILE_CHANGE#,
10 CONTROLFILE_TIME, OPEN_RESETLOGS, VERSION_TIME, OPEN_MODE, PROTECTION_MODE, PROT
11 ECTION_LEVEL, REMOTE_ARCHIVE, ACTIVATION#, SWITCHOVER#, DATABASE_ROLE, ARCHIVELO
12 G_CHANGE#, ARCHIVELOG_COMPRESSION, SWITCHOVER_STATUS, DATAGUARD_BROKER, GUARD_ST
13 ATUS, SUPPLEMENTAL_LOG_DATA_MIN, SUPPLEMENTAL_LOG_DATA_PK, SUPPLEMENTAL_LOG_DATA
14 _UI, FORCE_LOGGING, PLATFORM_ID, PLATFORM_NAME, RECOVERY_TARGET_INCARNATION#, LA
15 ST_OPEN_INCARNATION#, CURRENT_SCN, FLASHBACK_ON,SUPPLEMENTAL_LOG_DATA_FK, SUPPLE
16 MENTAL_LOG_DATA_ALL, DB_UNIQUE_NAME, STANDBY_BECAME_PRIMARY_SCN, FS_FAILOVER_STA
17 TUS, FS_FAILOVER_CURRENT_TARGET, FS_FAILOVER_THRESHOLD, FS_FAILOVER_OBSERVER_PRE
18 
19 VIEW_DEFINITION
20 --------------------------------------------------------------------------------
21 SENT, FS_FAILOVER_OBSERVER_HOST, CONTROLFILE_CONVERTED, PRIMARY_DB_UNIQUE_NAME,
22 SUPPLEMENTAL_LOG_DATA_PL, MIN_REQUIRED_CAPTURE_CHANGE# from GV$DATABASE where in
23 st_id = USERENV('Instance')
24 
25 
26 SQL>
27 SQL>
28 SQL> select VIEW_DEFINITION from v$fixed_view_definition where VIEW_NAME = 'GV$DATABASE';
29 
30 VIEW_DEFINITION
31 --------------------------------------------------------------------------------
32 select di.inst_id,di.didbi,di.didbn,to_date(di.dicts,'MM/DD/RR HH24:MI:SS','NLS_
33 CALENDAR=Gregorian'),to_number(di.dirls),to_date(di.dirlc,'MM/DD/RR HH24:MI:SS',
34 'NLS_CALENDAR=Gregorian'),to_number(di.diprs),to_date(di.diprc,'MM/DD/RR HH24:MI
35 :SS','NLS_CALENDAR=Gregorian'),decode(di.dimla,0,'NOARCHIVELOG',1,'ARCHIVELOG','
36 MANUAL'),to_number(di.discn),to_number(di.difas),decode(bitand(di.diflg,256),256
37 ,'CREATED',decode(bitand(di.diflg,1024),1024,'STANDBY',decode(bitand(di.diflg,32
38 768),32768,'CLONE',decode(bitand(di.diflg,4096),4096,'BACKUP','CURRENT')))),to_d
39 ate(di.dicct,'MM/DD/RR HH24:MI:SS','NLS_CALENDAR=Gregorian'),di.dicsq,to_number(
40 di.dickp_scn),to_date(di.dickp_tim,'MM/DD/RR HH24:MI:SS','NLS_CALENDAR=Gregorian
41 '),decode(bitand(di.diflg,4),4,'REQUIRED',decode(di.diirs,0,'NOT ALLOWED','ALLOW
42 ED')),to_date(di.divts,'MM/DD/RR HH24:MI:SS','NLS_CALENDAR=Gregorian'),decode(di
43 
44 VIEW_DEFINITION
45 --------------------------------------------------------------------------------
46 .didor,0,'MOUNTED',decode(di.didor,1,'READ WRITE',decode(di.didor,2,'READ ONLY',
47  'READ ONLY WITH APPLY'))),decode(bitand(di.diflg,65536),65536,'MAXIMUM PROTECTI
48 ON',decode(bitand(di.diflg,128),128,'MAXIMUM AVAILABILITY',decode(bitand(di.difl
49 g,134217728),134217728,'RESYNCHRONIZATION',decode(bitand(di.diflg,8),8,'UNPROTEC
50 TED','MAXIMUM PERFORMANCE')))),decode(di.diprt,1,'MAXIMUM PROTECTION',2,'MAXIMUM
51  AVAILABILITY',3,'RESYNCHRONIZATION',4,'MAXIMUM PERFORMANCE',5,'UNPROTECTED',  '
52 UNKNOWN'),decode(di.dirae,0,'DISABLED',1,'SEND',2,'RECEIVE',3,'ENABLED','UNKNOWN
53 '),to_number(di.diacid),to_number(di.diacid),decode(bitand(di.difl2,32768),32768
54 ,'SNAPSHOT STANDBY',decode(bitand(di.diflg,33554432),33554432,'LOGICAL STANDBY',
55 decode(bitand(di.diflg,1024),1024,'PHYSICAL STANDBY','PRIMARY'))),to_number(di.d
56 iars),decode(bitand(difl2,1),1,'ENABLED','DISABLED'),decode(di.disos,0,'IMPOSSIB
57 
58 VIEW_DEFINITION
59 --------------------------------------------------------------------------------
60 LE',1,'NOT ALLOWED',2,'SWITCHOVER LATENT',3,'SWITCHOVER PENDING',4,'TO PRIMARY',
61 5,'TO STANDBY',6,'RECOVERY NEEDED',7,'SESSIONS ACTIVE',8,'PREPARING SWITCHOVER',
62 9,'PREPARING DICTIONARY',10,'TO LOGICAL STANDBY',11,'FAILED DESTINATION',12,'RES
63 OLVABLE GAP',13,'LOG SWITCH GAP',14,'UNRESOLVABLE GAP',NULL),decode(di.didgd,0,'
64 DISABLED','ENABLED'),decode(bitand(di.diflg,1048576),1048576,'ALL',decode(bitand
65 (di.diflg,2097152),2097152,'STANDBY','NONE')),decode(bitand(diflg,1073741824),10
66 73741824, 'YES',               decode(bitand(diflg, 131072 + 262144 + 524288),0,
67                       decode(bitand(difl2,2 + 64), 0,'NO','IMPLICIT'),
68            'IMPLICIT')),decode(bitand(di.diflg,131072),131072,'YES','NO'),decode
69 (bitand(di.diflg,262144),262144,'YES','NO'),decode(bitand(di.diflg,268435456),26
70 8435456,'YES','NO'),di.diplid, di.dipln, di2.di2rdi, di2.di2inc,to_number(di.dic
71 
72 VIEW_DEFINITION
73 --------------------------------------------------------------------------------
74 ur_scn),decode(bitand(di2.di2flag,1),1,'YES',               decode(di2.di2rsp_ol
75 dest,0,'NO','RESTORE POINT ONLY')),decode(bitand(diflg,524288),524288,'YES','NO'
76 ),decode(bitand(difl2,2),2,'YES','NO'),di2.di2dbun, to_number(di2.di2actiscn), d
77 ecode(di.difsts,0,'DISABLED',1,'BYSTANDER',2,'SYNCHRONIZED',3,'UNSYNCHRONIZED',4
78 ,'SUSPENDED',5,'STALLED',6,'LOADING DICTIONARY',7,'PRIMARY UNOBSERVED',8,'REINST
79 ATE REQUIRED',10,'REINSTATE FAILED',11,'TARGET OVER LAG LIMIT',12,'TARGET UNDER
80 LAG LIMIT',''), di.diftgt, di.difths,decode(di.difopr,1,'YES',2,'NO',3,'UNKNOWN'
81 ,''), di.difobs, decode(bitand(difl2, 16384), 16384, 'YES', 'NO'), di2.di2pdbun,
82  decode(bitand(di.difl2,64), 64, 'YES', 'NO'), decode(di2.di2min_req_capture_scn
83 , 0, to_number(null),         di2.di2min_req_capture_scn) from x$kccdi di, x$kcc
84 di2 di2
85 
86 VIEW_DEFINITION
87 --------------------------------------------------------------------------------
88 
89 
90 SQL>
91 SQL>

可以知道，视图V$DATABASE的数据来自于视图GV$DATABASE；而GV$DATABASE的数据来自于下面2个表：

x$kccdi di, x$kccdi2 di2

都是数据库内部表。

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原文地址：https://www.cnblogs.com/andypeker/p/6188101.html