SQL> ALTER SESSION SET tracefile_identifier = '10046';

Session altered.

SQL> ALTER SESSION SET timed_statistics = true;

Session altered.

SQL> ALTER SESSION SET statistics_level = all;

Session altered.

SQL> ALTER SESSION SET max_dump_file_size = unlimited;

Session altered.

SQL> ALTER SESSION SET events '10046 trace name context forever,level 12';

Session altered.

  2  (
  3     SELECT a.synonym_name, b.table_name, a.owner
  4       FROM dba_synonyms a, dba_tables b
  5      WHERE a.synonym_name = b.table_name
  6  ) ; 


SQL> ALTER SESSION SET events '10046 trace name context off';

Session altered.

SQL> exit

SQL> SELECT name, value FROM v$parameter WHERE name = 'user_dump_dest' ;

NAME                 VALUE
-------------------- ----------
user_dump_dest       /u01/trace 

PARSING IN CURSOR #140584383934648 len=138 dep=0 uid=0 oct=3 lid=0 
tim=1699354797 hv=4163043499 ad='a334bf78' sqlid='00gy33bw2605b'

select count(*) from
select a.synonym_name,b.table_name,a.owner
from dba_synonyms a, dba_tables b
where a.synonym_name = b.table_name

CURSOR number is #140584383934648

"len" is the length of the current SQL statement. 
(in this case 138 characters)

"dep" is the recursive depth of the cursor. 
(level "0" corresponds to the root operation).

"uid" is the schema ID under which SQL was parsed. 
(in this case "0" is "sys" user ID). 

"oct" is Oracle command type. 
(in this case "3" corresponds to a "select" statement).

"lid" is the Oracle privilege user id. 
(in this case "0" is "sys" user ID).

"tim" is the value in V$TIMER when the line was executed.

"hv" is the corresponding hash id for this statement.

"ad" is the library cache address of the cursor as is shown in V$SQL.

"sqlid" is the SQL identifier of a cached cursor as is shown in V$SQLTEXT.

EXEC #140584383934648:c=0,e=276,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,

EXEC means that a pre-parsed statement was executed.

"c" is CPU time measured in microseconds.

"e" elapsed time measured in microseconds.

"p" is the number of physical reads.

"cr" is the number of buffers retrieved for CR reads.

"cu" is the number of buffers retrieved in current mode.

"mis" cursor missed in the cache.

"r" is the number of rows processed.

"dep" is the recursive call depth (0 = user SQL, >0 = recursive).

"og" Optimizer goal: 1=All_Rows, 2=First_Rows, 3=Rule, 4=Choose.
(in this example "All_Rows" option was performed).

"plh" This value provides the execution plan hash value.

"tim" is the timestamp when the statement was executed.

WAIT #140584383934648: nam='db file sequential read' 
ela= 28671 file#=1 block#=1184 blocks=1 obj#=103 tim=1699388527

WAIT is an event that we waited for.

"nam" is *what* was being waited for. 
The wait events here are the same shown in V$SESSION_WAIT view.

"ela" is the elapsed time for the current operation in microseconds.
(1 second = 1,000,000 micro-seconds)

"file#" is file ID as shown in V$DATAFILE view.

"block#" is the starting block ID.

"blocks" represents how many blocks were involved.

"obj#" is the object ID of row source. 
(-1 if it was not associated with any particular object).

"tim" is the timestamp of the statement execution.

Completed WAITing under CURSOR 140584383934648 for "db file sequential read". 

We wait 28671 microseconds (aprox. 29 milliseconds) for a read of file #1. 

Start block was #1184 for 1 Oracle block of object number #103. 

Operation was done at timestamp 1699388527.