Oracle Interview Questions and Answers
Question - 91 : - How can one see who is using a temporary segment?
Answer - 91 : - For every user using temporary space, there is an entry in SYS.V$_LOCK with type 'TS'.
All temporary segments are named 'ffff.bbbb' where 'ffff' is the file it is in and 'bbbb' is first block of the segment. If your temporary tablespace is set to TEMPORARY, all sorts are done in one large temporary segment. For usage stats, see SYS.V_$SORT_SEGMENT
From Oracle 8.0, one can just query SYS.v$sort_usage. Look at these examples:
select s.username, u."USER", u.tablespace, u.contents, u.extents, u.blocks
from sys.v_$session s, sys.v_$sort_usage u
where s.addr = u.session_addr
/
select s.osuser, s.process, s.username, s.serial#,
Sum (u.blocks)*vp.value/1024 sort_size
from sys.v_$session s, sys.v_$sort_usage u, sys.v_$parameter VP
where s.saddr = u.session_addr
and vp.name = 'db_block_size'
and s.osuser like '&1'
group by s.osuser, s.process, s.username, s.serial#, vp.value
/
Question - 92 : - How does one get the view definition of fixed views/tables?
Answer - 92 : - Query v$fixed_view_definition. Example: SELECT * FROM v$fixed_view_definition WHERE view_name='V$SESSION';
Question - 93 : - What are the dictionary tables used to monitor a database spaces ?
Answer - 93 : - DBA_FREE_SPACE
DBA_SEGMENTS
DBA_DATA_FILES.
Question - 94 : - How can we specify the Archived log file name format and destination?
Answer - 94 : - By setting the following values in init.ora file. LOG_ARCHIVE_FORMAT = arch %S/s/T/tarc (%S - Log sequence number and is zero left paded, %s - Log sequence number not padded. %T - Thread number lef-zero-paded and %t - Thread number not padded). The file name created is arch 0001 are if %S is used. LOG_ARCHIVE_DEST = path.
Question - 95 : - What is user Account in Oracle database?
Answer - 95 : - An user account is not a physical structure in Database but it is having important relationship to the objects in the database and will be having certain privileges.
Question - 96 : - When will the data in the snapshot log be used?
Answer - 96 : - We must be able to create a after row trigger on table (i.e., it should be not be already available) After giving table privileges. We cannot specify snapshot log name because oracle uses the name of the master table in the name of the database objects that support its snapshot log. The master table name should be less than or equal to 23 characters. (The table name created will be MLOGS_tablename, and trigger name will be TLOGS name).
Question - 97 : - What dynamic data replication?
Answer - 97 : - Updating or Inserting records in remote database through database triggers. It may fail if remote database is having any problem.
Question - 98 : - What is Two-Phase Commit ?
Answer - 98 : - Two-phase commit is mechanism that guarantees a distributed transaction either commits on all involved nodes or rolls back on all involved nodes to maintain data consistency across the global distributed database. It has two phase, a Prepare Phase and a Commit Phase.
Question - 99 : - How can you Enforce Referential Integrity in snapshots ?
Answer - 99 : - Time the references to occur when master tables are not in use. Peform the reference the manually immdiately locking the master tables. We can join tables in snopshots by creating a complex snapshots that will based on the master tables.
Question - 100 : - What is a SQL * NET?
Answer - 100 : - SQL *NET is ORACLE's mechanism for interfacing with the communication protocols used by the networks that facilitate distributed processing and distributed databases. It is used in Clint-Server and Server-Server communications.