V$SQL View underlying definition

Question

HI
Is it possible to get underlying deifintion of v$views ? ( if i query text from dba_views i see v_$sql is selecting from v$sql)
I want to know what are the underlying tables used for v$sql.How can i find that
Thanks

Answer 1

sb92075 wrote:
894365 wrote:
HI
Is it possible to get underlying deifintion of v$views ? ( if i query text from dba_views i see v_$sql is selecting from v$sql)
I want to know what are the underlying tables used for v$sql.How can i find thatAny/all of the V$* "views" query SGA data structures & are presented as regular SQL Views.Which may be true, but doesn't answer his question.
The way it works is, let's take V$SQL as an example:
SQL> select owner,object_type,object_name from dba_objects where object_name='V$SQL';
OWNER        OBJECT_TYPE            OBJECT_NAME
PUBLIC        SYNONYM            V$SQL
SQL> So, V$SQL is actually a public synonym. Let's see what it points at:
SQL> exec print_table('select owner,synonym_name,table_owner,table_name,db_link from dba_synonyms where owner=''PUBLIC'' and synonym_name = ''V$SQL''');
OWNER                     : PUBLIC
SYNONYM_NAME                : V$SQL
TABLE_OWNER                : SYS
TABLE_NAME                : V_$SQL
DB_LINK                 :
PL/SQL procedure successfully completed.Now, we can see that V$SQL is a public synonym that points to SYS.V_$SQL. Now, DBA_SYNONYMS says it's a table, but, it could also be a view. And, in this case, it is a view.
We can see that here:
SQL> exec print_table('select owner,object_type,object_name from dba_objects where owner=''SYS'' and object_name =''V_$SQL''');
OWNER                     : SYS
OBJECT_TYPE                : VIEW
OBJECT_NAME                : V_$SQL
PL/SQL procedure successfully completed.Ok, so V_$SQL is a view.
Let's see what it's definition is:
SQL> exec print_table('select text from dba_views where owner=''SYS'' and view_name = ''V_$SQL''');
TEXT                     : select
"SQL_TEXT","SQL_FULLTEXT","SQL_ID","SHARABLE_MEM","PERSISTENT_MEM","RUNTIME_MEM"
,"SORTS","LOADED_VERSIONS","OPEN_VERSIONS","USERS_OPENING","FETCHES","EXECUTIONS
","PX_SERVERS_EXECUTIONS","END_OF_FETCH_COUNT","USERS_EXECUTING","LOADS","FIRST_
LOAD_TIME","INVALIDATIONS","PARSE_CALLS","DISK_READS","DIRECT_WRITES","BUFFER_GE
TS","APPLICATION_WAIT_TIME","CONCURRENCY_WAIT_TIME","CLUSTER_WAIT_TIME","USER_IO
_WAIT_TIME","PLSQL_EXEC_TIME","JAVA_EXEC_TIME","ROWS_PROCESSED","COMMAND_TYPE","
OPTIMIZER_MODE","OPTIMIZER_COST","OPTIMIZER_ENV","OPTIMIZER_ENV_HASH_VALUE","PAR
SING_USER_ID","PARSING_SCHEMA_ID","PARSING_SCHEMA_NAME","KEPT_VERSIONS","ADDRESS
","TYPE_CHK_HEAP","HASH_VALUE","OLD_HASH_VALUE","PLAN_HASH_VALUE","CHILD_NUMBER"
,"SERVICE","SERVICE_HASH","MODULE","MODULE_HASH","ACTION","ACTION_HASH","SERIALI
ZABLE_ABORTS","OUTLINE_CATEGORY","CPU_TIME","ELAPSED_TIME","OUTLINE_SID","CHILD_
ADDRESS","SQLTYPE","REMOTE","OBJECT_STATUS","LITERAL_HASH_VALUE","LAST_LOAD_TIME
","IS_OBSOLETE","IS_BIND_SENSITIVE","IS_BIND_AWARE","IS_SHAREABLE","CHILD_LATCH"
,"SQL_PROFILE","SQL_PATCH","SQL_PLAN_BASELINE","PROGRAM_ID","PROGRAM_LINE#","EXA
CT_MATCHING_SIGNATURE","FORCE_MATCHING_SIGNATURE","LAST_ACTIVE_TIME","BIND_DATA"
,"TYPECHECK_MEM","IO_CELL_OFFLOAD_ELIGIBLE_BYTES","IO_INTERCONNECT_BYTES","PHYSI
CAL_READ_REQUESTS","PHYSICAL_READ_BYTES","PHYSICAL_WRITE_REQUESTS","PHYSICAL_WRI
TE_BYTES","OPTIMIZED_PHY_READ_REQUESTS","LOCKED_TOTAL","PINNED_TOTAL","IO_CELL_U
NCOMPRESSED_BYTES","IO_CELL_OFFLOAD_RETURNED_BYTES" from v$sql
PL/SQL procedure successfully completed.Huh? How can V_$SQL be based on V$SQL, when V$SQL is a synonym that points to V_$SQL??
Well, this is where the trick comes in. SYS.V$SQL is a fixed view, i.e. a view that is owned by SYS and starts with 'V$' or 'GV$'.
So, we can look at V$FIXED_VIEW_DEFINITION to see the definition of SYS.V$SQL:
SQL> exec print_table('select view_definition from v$fixed_view_definition where view_name = ''V$SQL''');
VIEW_DEFINITION            : select     SQL_TEXT , SQL_FULLTEXT , SQL_ID,
SHARABLE_MEM , PERSISTENT_MEM , RUNTIME_MEM , SORTS , LOADED_VERSIONS ,
OPEN_VERSIONS , USERS_OPENING , FETCHES , EXECUTIONS , PX_SERVERS_EXECUTIONS ,
END_OF_FETCH_COUNT, USERS_EXECUTING , LOADS , FIRST_LOAD_TIME, INVALIDATIONS,
PARSE_CALLS , DISK_READS , DIRECT_WRITES , BUFFER_GETS , APPLICATION_WAIT_TIME,
CONCURRENCY_WAIT_TIME, CLUSTER_WAIT_TIME, USER_IO_WAIT_TIME, PLSQL_EXEC_TIME,
JAVA_EXEC_TIME, ROWS_PROCESSED , COMMAND_TYPE , OPTIMIZER_MODE , OPTIMIZER_COST,
OPTIMIZER_ENV, OPTIMIZER_ENV_HASH_VALUE, PARSING_USER_ID , PARSING_SCHEMA_ID ,
PARSING_SCHEMA_NAME, KEPT_VERSIONS , ADDRESS , TYPE_CHK_HEAP , HASH_VALUE,
OLD_HASH_VALUE, PLAN_HASH_VALUE, CHILD_NUMBER, SERVICE, SERVICE_HASH, MODULE,
MODULE_HASH , ACTION , ACTION_HASH ,  SERIALIZABLE_ABORTS , OUTLINE_CATEGORY,
CPU_TIME, ELAPSED_TIME, OUTLINE_SID, CHILD_ADDRESS, SQLTYPE, REMOTE,
OBJECT_STATUS, LITERAL_HASH_VALUE, LAST_LOAD_TIME, IS_OBSOLETE,
IS_BIND_SENSITIVE, IS_BIND_AWARE, IS_SHAREABLE,CHILD_LATCH, SQL_PROFILE,
SQL_PATCH, SQL_PLAN_BASELINE, PROGRAM_ID, PROGRAM_LINE#,
EXACT_MATCHING_SIGNATURE, FORCE_MATCHING_SIGNATURE, LAST_ACTIVE_TIME, BIND_DATA,
TYPECHECK_MEM, IO_CELL_OFFLOAD_ELIGIBLE_BYTES, IO_INTERCONNECT_BYTES,
PHYSICAL_READ_REQUESTS, PHYSICAL_READ_BYTES, PHYSICAL_WRITE_REQUESTS,
PHYSICAL_WRITE_BYTES, OPTIMIZED_PHY_READ_REQUESTS, LOCKED_TOTAL, PINNED_TOTAL,
IO_CELL_UNCOMPRESSED_BYTES, IO_CELL_OFFLOAD_RETURNED_BYTES from GV$SQL where
inst_id = USERENV('Instance')
PL/SQL procedure successfully completed.So, SYS.V$SQL is based on GV$SQL. So, what's GV$SQL??
SQL> exec print_table('select owner,object_type,object_name from dba_objects where object_name =''GV$SQL''');
OWNER                     : PUBLIC
OBJECT_TYPE                : SYNONYM
OBJECT_NAME                : GV$SQL
PL/SQL procedure successfully completed.Another synonym?? Where does it all end?? (Hang in there, we're almost there!)
So, what does the GV$SQL synonym point to?
SQL> exec print_table('select * from dba_synonyms where owner=''PUBLIC'' and synonym_name = ''GV$SQL''');
OWNER                     : PUBLIC
SYNONYM_NAME                : GV$SQL
TABLE_OWNER                : SYS
TABLE_NAME                : GV_$SQL
DB_LINK                 :
PL/SQL procedure successfully completed.Ok, so, now we have GV_$SQL. What's that, exactly? Is it really a table? Or perhaps another view?
SQL> exec print_table('select owner,object_type,object_name from dba_objects where owner=''SYS'' and object_name = ''GV_$SQL''');
OWNER                     : SYS
OBJECT_TYPE                : VIEW
OBJECT_NAME                : GV_$SQL
PL/SQL procedure successfully completed.Ok, so GV_$SQL is another view. Let's look at that definition!
SQL> exec print_Table('select text from dba_views where owner=''SYS'' and view_name = ''GV_$SQL''');
TEXT                     : select
"INST_ID","SQL_TEXT","SQL_FULLTEXT","SQL_ID","SHARABLE_MEM","PERSISTENT_MEM","RU
NTIME_MEM","SORTS","LOADED_VERSIONS","OPEN_VERSIONS","USERS_OPENING","FETCHES","
EXECUTIONS","PX_SERVERS_EXECUTIONS","END_OF_FETCH_COUNT","USERS_EXECUTING","LOAD
S","FIRST_LOAD_TIME","INVALIDATIONS","PARSE_CALLS","DISK_READS","DIRECT_WRITES",
"BUFFER_GETS","APPLICATION_WAIT_TIME","CONCURRENCY_WAIT_TIME","CLUSTER_WAIT_TIME
","USER_IO_WAIT_TIME","PLSQL_EXEC_TIME","JAVA_EXEC_TIME","ROWS_PROCESSED","COMMA
ND_TYPE","OPTIMIZER_MODE","OPTIMIZER_COST","OPTIMIZER_ENV","OPTIMIZER_ENV_HASH_V
ALUE","PARSING_USER_ID","PARSING_SCHEMA_ID","PARSING_SCHEMA_NAME","KEPT_VERSIONS
","ADDRESS","TYPE_CHK_HEAP","HASH_VALUE","OLD_HASH_VALUE","PLAN_HASH_VALUE","CHI
LD_NUMBER","SERVICE","SERVICE_HASH","MODULE","MODULE_HASH","ACTION","ACTION_HASH
","SERIALIZABLE_ABORTS","OUTLINE_CATEGORY","CPU_TIME","ELAPSED_TIME","OUTLINE_SI
D","CHILD_ADDRESS","SQLTYPE","REMOTE","OBJECT_STATUS","LITERAL_HASH_VALUE","LAST
_LOAD_TIME","IS_OBSOLETE","IS_BIND_SENSITIVE","IS_BIND_AWARE","IS_SHAREABLE","CH
ILD_LATCH","SQL_PROFILE","SQL_PATCH","SQL_PLAN_BASELINE","PROGRAM_ID","PROGRAM_L
INE#","EXACT_MATCHING_SIGNATURE","FORCE_MATCHING_SIGNATURE","LAST_ACTIVE_TIME","
BIND_DATA","TYPECHECK_MEM","IO_CELL_OFFLOAD_ELIGIBLE_BYTES","IO_INTERCONNECT_BYT
ES","PHYSICAL_READ_REQUESTS","PHYSICAL_READ_BYTES","PHYSICAL_WRITE_REQUESTS","PH
YSICAL_WRITE_BYTES","OPTIMIZED_PHY_READ_REQUESTS","LOCKED_TOTAL","PINNED_TOTAL",
"IO_CELL_UNCOMPRESSED_BYTES","IO_CELL_OFFLOAD_RETURNED_BYTES" from gv$sql
PL/SQL procedure successfully completed.Another GV$SQL?? Does this ever end???
Back to V$FIXED_VIEW_DEFINITION for the final round:
SQL> exec print_table('select view_definition from v$fixed_view_definition where view_name = ''GV$SQL''');
VIEW_DEFINITION            : select inst_id,kglnaobj,kglfnobj,kglobt03,
kglobhs0+kglobhs1+kglobhs2+kglobhs3+kglobhs4+kglobhs5+kglobhs6+kglobt16,
kglobt08+kglobt11, kglobt10, kglobt01, decode(kglobhs6,0,0,1),
decode(kglhdlmd,0,0,1), kglhdlkc, kglobt04, kglobt05, kglobt48, kglobt35,
kglobpc6, kglhdldc, substr(to_char(kglnatim,'YYYY-MM-DD/HH24:MI:SS'),1,19),
kglhdivc, kglobt12, kglobt13, kglobwdw, kglobt14, kglobwap, kglobwcc, kglobwcl,
kglobwui, kglobt42, kglobt43, kglobt15, kglobt02, decode(kglobt32,       0,
'NONE',        1, 'ALL_ROWS',          2, 'FIRST_ROWS',          3, 'RULE',
4, 'CHOOSE',            'UNKNOWN'), kglobtn0, kglobcce, kglobcceh, kglobt17,
kglobt18, kglobts4, kglhdkmk, kglhdpar, kglobtp0, kglnahsh, kglobt46, kglobt30,
kglobt09, kglobts5, kglobt48, kglobts0, kglobt19, kglobts1, kglobt20, kglobt21,
kglobts2, kglobt06, kglobt07, decode(kglobt28, 0, to_number(NULL), kglobt28),
kglhdadr, kglobt29, decode(bitand(kglobt00,64),64, 'Y', 'N'), decode(kglobsta,
1, 'VALID',        2, 'VALID_AUTH_ERROR',      3, 'VALID_COMPILE_ERROR',
4, 'VALID_UNAUTH',       5, 'INVALID_UNAUTH',           6, 'INVALID'), kglobt31,
substr(to_char(kglobtt0,'YYYY-MM-DD/HH24:MI:SS'),1,19), decode(kglobt33, 1, 'Y',
'N'),  decode(bitand(kglobacs, 1), 1, 'Y', 'N'),  decode(bitand(kglobacs, 2), 2,
'Y', 'N'),  decode(bitand(kglobacs, 4), 4, 'Y', 'N'),  kglhdclt, kglobts3,
kglobts7, kglobts6, kglobt44, kglobt45,  kglobt47, kglobt49, kglobcla,
kglobcbca, kglobt22, kglobt52, kglobt53, kglobt54, kglobt55,  kglobt56,
kglobt57, kglobt58, kglobt23, kglobt24, kglobt59,  kglobt53 -
((kglobt55+kglobt57) - kglobt52)  from x$kglcursor_childSo, here we are, finally, we get to the fabled 'X$' table! An X$ table is hardcoded into the Oracle kernel, and it's a table projection of a chunk of the SGA memory. It's can't be updated, only queried, and is not subject to read consistency.
I'm sure this post will raise questions, but it's already too long, so, I'll leave it at that.
Feel free to ask follow up questions, and I'll try to address them.
Hope that helps,
-Mark