OCA Exam Quiz: Oracle Database Administration!

1. Which of these background processes is optional?

ARCn, the archive process

CKPT, the checkpoint process

DBWn, the database writer

LGWR, the log writer

MMON, the manageability monitor

A. Archiving is not compulsory (though it is usually a good idea).
B, C, D, E CKPT, DBWn, LGWR and MMON are all necessary processes.

Explanation

A. Archiving is not compulsory (though it is usually a good idea).
B, C, D, E CKPT, DBWn, LGWR and MMON are all necessary processes.

2. How many sessions communicate with the database?

Server processes use Oracle Net to connect to the instance.

Background processes use Oracle Net to connect to the database.

User processes read from the databae and write to the database.

Server processes execute SQL received from user processes.

A, D and F. Every instance must have a database buffer cache, a log buffer, and a shared pool. B, C are wong because Jave Pool, the large pool and the strema pool are only needed for certain option.

Explanation

A, D and F. Every instance must have a database buffer cache, a log buffer, and a shared pool. B, C are wong because Jave Pool, the large pool and the strema pool are only needed for certain option.

3. Where is the current redo byte address, also known as the incremental checkpoint positions, recorded?

In the controlfile

In the current online log file group

In the header of each datafile

In the system global area

A. The checkpoint process writes the RBA to the controlfile.
B,C, and D. The online logs, the datafiles, and SGA have no knowledge of where the current RBA is.

Explanation

A. The checkpoint process writes the RBA to the controlfile.
B,C, and D. The online logs, the datafiles, and SGA have no knowledge of where the current RBA is.

4. Which statement is correct regarding the online redo log?

There must be at least one log file group, with at least one memeber

There must be at least one log file group, with at least two memebers

There must be at least two log file group, with at least one memebers each

There must be at least two log file group, with at least two memebers eacg

C. Two groups of one memeber is the minimum required for the database to function. A & B are wrong because at least two groups are always required. D is wrong because while it is certainly advisable to multiplex the members, it is not technical requirement.

Explanation

C. Two groups of one memeber is the minimum required for the database to function. A & B are wrong because at least two groups are always required. D is wrong because while it is certainly advisable to multiplex the members, it is not technical requirement.

5. What happens when a user issues a COMMITT?

The CKPT process signals a checkpoint

The DBNw process writes the transaction's changed buffers to the datafiles.

The LGWR flushes the log buffer to the online redo log.

The ARCn process writes the change vectors to the archive redo log.

C. On COMMITT, the log writer flushes the log buffer to disk. No other background processes need do anything..
A is wrong because checkpoiont only occur on request, or on orderly shutdown. B is wrong because the algorithm DBWn uses to select buffers to write to the datafiles is not related to COMMIT processing, but to how busy the buffer is. D is wrong because ARCn only copies filled online redo logs; it doesn't copy change vectors in real time.

Explanation

C. On COMMITT, the log writer flushes the log buffer to disk. No other background processes need do anything..
A is wrong because checkpoiont only occur on request, or on orderly shutdown. B is wrong because the algorithm DBWn uses to select buffers to write to the datafiles is not related to COMMIT processing, but to how busy the buffer is. D is wrong because ARCn only copies filled online redo logs; it doesn't copy change vectors in real time.

6. When a session changes data, where does the change get written?

To the data block in the cache, and the redo log buffer.

To the data block on disk, and the current online redo log file.

The session writes to the database buffer cache, and the log writer to the current online redo log file.

Nothing the written until the change is committed.

A. The session updates the copy of the block in memory and writes out the change vector to the log buffer.
B is wrong, because while this will happen, it does not happen when the change is made. C is wrong because it confuses the session making changes in memory with LGWR propagating changes to disk. D is wrong because all changes to data occur in memory as they are made - the COMMITT is not relevant.

Explanation

A. The session updates the copy of the block in memory and writes out the change vector to the log buffer.
B is wrong, because while this will happen, it does not happen when the change is made. C is wrong because it confuses the session making changes in memory with LGWR propagating changes to disk. D is wrong because all changes to data occur in memory as they are made - the COMMITT is not relevant.

7. What statements regarding instance memory and session memory are correct?

SGA memory is private memory segements: PGA memory is shared memory segments.

Session can write to the PGA, not the SGA.

The SGA is written to by all sessions: a PGA is written by one session.

The PGA is allocated at instance startup.

The SGA is allocated at instance startup.

C and E. The SGA is shared memory updated by all sessions; PGAs are private to each session. The SGA is allocated at startup time (but it can be modified later).
A is wrong because it reverses the situation: it is the SGA that exists in shared memory, not the PGA. B is wrong because sessions write to both their own PGA and to the SGA. D is wrong because (unlike the SGA) the PGA is only allocated on demand.

Explanation

C and E. The SGA is shared memory updated by all sessions; PGAs are private to each session. The SGA is allocated at startup time (but it can be modified later).
A is wrong because it reverses the situation: it is the SGA that exists in shared memory, not the PGA. B is wrong because sessions write to both their own PGA and to the SGA. D is wrong because (unlike the SGA) the PGA is only allocated on demand.

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8. What memory structures are a required part of the SGA?

The database buffer cache

The Java Pool

The large pool

The log buffer

The program global area

D. This is the client-server split: user processes generate SQL; server process execute SQL.
A and B are wrong because they get the use of Oracle Net wrong. Oracle Net is the protocol between a user process and server process. C is wrong because it describes what server process do, not what user processes do.

Explanation

D. This is the client-server split: user processes generate SQL; server process execute SQL.
A and B are wrong because they get the use of Oracle Net wrong. Oracle Net is the protocol between a user process and server process. C is wrong because it describes what server process do, not what user processes do.

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9. An Oracle instance can have only one of some processes, but several of others. Which of these processes can occur several times?

The archive process

The checkpoint process

The database writer process

The log writer process

The session server process

A, C, and E. A and C are correct because the DBA can choose to configure multiple archive and database writer process. E is correct because one server process will be launched for every concurrent session. B & D are wong because an instance can have only one log writer process and only one checkpoint process.

Explanation

A, C, and E. A and C are correct because the DBA can choose to configure multiple archive and database writer process. E is correct because one server process will be launched for every concurrent session. B & D are wong because an instance can have only one log writer process and only one checkpoint process.

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