The oracledba interview questions are basically missing 55555

1. Linux File System creation process

2. Role of the LMS Process

3. Set archiving Mode

4. How to Use RMAN to back up USER tablespace and restore the process

What is the function of the 5 DML lock? Which blocking methods are available?

6. How to check whether the table is locked and how to unlock it

7 enquenue generation

8 _ uploupted_rollback_segments

9 _ offline_rollback_segments

10 enable and disable SQL apply for the logical standby Database

11 which system file should I set for Linux during Oracle 10g installation?

Bytes -------------------------------------------------------------------------------------------------
3. Set archiving Mode
SVRMGR> archive log list
SVRMGRL> shutdown
SVRMGRL> startup mount
SVRMGRL> alter database archivelog
SVRMGRL> alter database open;

What is the function of the 5 DML lock? Which blocking methods are available?
A) DML locks can be divided into row locks, table locks, and deadlocks.
DML-level blocking is used to control data manipulation in concurrent transactions to ensure data consistency and integrity. The blocking objects can be tables or rows.
Oracle can automatically block user data for data manipulation. However, if authorization is available, a blocking is implemented to meet the needs of concurrent manipulation. DML blocking can be implemented by a user process in explicit locking or by implicit SQL statements.
DML locks can be blocked in the following three ways:
(1) shared blocking (SHARE)
(2) Exclusive Blocking)
(3) share update Blocking)
Here, share and exclusive are used for table blocking, while share update is used for row blocking.

7 enquenue generation
Enqueue is a lock mechanism to protect shared resources. This locking mechanism protects shared resources, such as recorded data,
To avoid two people updating the same data at the same time. Enqueue includes a queuing system, namely, FIFO (first-in-first-out)
Queuing mechanism. Note: the latch mechanism of Oracle is not FIFO. Enqueue wait usually refers to St enqueue,
HW enqueue, tx4 enqueue, and TM enqueue.
A. St enqueue is used to allocate tablespaces for space management and dictionary management. Use LMT or try
Pre-allocate, or at least make the next region larger than the problematic dictionary-managed tablespace.
B. HW enqueue is used together with the high-water mark of the segment; manual allocation of the area can avoid this wait.
C and tx4 enqueue are the most common enqueue waits. They are usually the results of one of the following three problems:
The first problem is that duplicate indexes in the unique index must be committed/rolled back.
To release the enqueue.
The second problem is that the same bitmap index segment is updated multiple times. Because a single bitmap segment may contain multiple row addresses
(Rowid), so when multiple users try to update the same segment, You need to submit or roll back the operation to release the enqueue.
The third and most likely problem is that multiple users update the same block at the same time. If you are not free
Block-level locks will occur in the ITL slot. Multiple ITL slots can be used by increasing initrans and/or maxtrans,
Or increase the pctfree value of the table to avoid this situation easily.
D. TM enqueue is generated during DML to avoid using DDL for affected objects. If there are external keywords
You must index them to avoid this common locking problem.

11 which system file should I set for Linux during Oracle 10g installation?
Cat>/etc/sysctl. conf <EOF
Kernel. shmall = 2097152
Kernel. shmmax = 2147483648
Kernel. shmmni = 4096
Kernel. sem = 250 32000 100 128
Fs. file-max = 65536
Net. ipv4.ip _ local_port_range = 1024 65000
EOF
/Sbin/sysctl-p

Cat>/etc/security/limits. conf <EOF
Oracle soft nproc 2047
Hard nproc 16384
Oracle soft nofile 1024
Oracle hard nofile 65536
EOF

Cat>/etc/pam. d/login <EOF
Session required/lib/security/pam_limits.so
EOF

/Etc/security/limits. conf

4. How to Use RMAN to back up USER tablespace and restore the process
RMAN> backup tablespace vsafe plus archivelog delete input;
RMAN> run {
2> allocate channel c1 type 'sbt _ tape ';
3> restore tablespace 'test ';
4> recover tablespace 'test ';
5> release channel c1;
6>}

12 which dynamic views can be viewed when the database is slow?
V $ Session, V $ Session_wait, V $ system_Event, V $ SqlText, V $ SQlarea, v $ session_longops

12 which dynamic views can be viewed when the database is slow?