由 guest 发布于: 2001-02-07 17:33

怎样才能通过ORACLE8DBA(OCP)考试

Hi, little fish

I can share my tips, but I find your website have not the oracle certification.
You can add it. If my tips can help you, tell me.

Best regards,

Sandy
　　　　　　　　　　
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How to pass the ORACLE 8 DBA(OCP) exam:

1. Get and read the student books from oracle or your friend(12 total), all the content in the books.
2. Do the assess exam.(run the attachment file assess.exe to install it).
　（Download assess.exe）.
3. You can find more information at Oracle website.
4. Other tips below:

1Z0-001 - Into to Oracle: SQL and PL/SQL

1.An expr. with NULL always evaluates to NULL, except ||, which treats NULL as ''
2.Comparison to NULL is always FALSE
3.All functions, except COUNT(*), ignores NULL values
4.NULLS are displayed last with ORDERED BY in Oracle8
5.Logical evaluation: TRUE takes precedence with OR, FALSE with AND
6.There are a lot of questions about GROUP BY/ HAVING...
7.Use WHERE to exclude rows, HAVING to exclude groups from a query
8.Know when a cartesian product will be formed. You need a min of N-1 conditions when you join N tables.
9.Know the difference between an equi (=), self (must use tab aliases), outer (+) and non-equi (IN, etc) join
10.You can only have a subquery in a FROM/ WHERE/ HAVING clause of a SELECT statement
11.Sub-queries and VIEWS cannot contain ORDER BY
12.A literal is any char/num/expr in a SELECT LIST that's not a col or col alias
13.MIN and MAX are the only functions that can operate on any datatype
14.PRIMARY KEY and UNIQUE constraints will implicitly create INDEXES
15.There is a lot of questions like: "Which line will return an error?". Look for names starting with numbers, invalid constraints, etc.

1Z0-013 - Oracle8: Database Administration

1.INSTANCE=SGA + background processed (not server processes); INSTANCE will open a DATABASE on disk
2.SGA=System Global Area/ PGA=Program Global Area
3.Oracle server creates PGA as writeable and non-shared/ SGA as shared
4.Know what background processes are doing in detail, DBWR, SMON, PMON, LGWR, etc.
5.SMON coalesces adjacent free extents into larger extent
6.Server processes executes SQL; Main phases are PARSE (setup parse tree=most effective search path), EXECUTE (apply parse tree) and FETCH (get rows)
7.Server configurations: single-task, two-task (dedicated server), MTS (shared server)
8.Shared Server: SQL*Net2/8 required, one requestQ for system, responseQ per dispatcher
9.Dedicated Server: use for batch, connect internal, server manager
10.With shared server session data and cursor state moves to SGA, stack space remains in PGA
11.No quota means segments cannot grow or be created, only object owner needs quotas.
12.By default a user has no access to any TS
13.If quota=0 NO ACCESS; -1=UNLIMITED (see view sys.dba_ts_quotas)
14.Clusters pre-allocate space/ 2 types: index clusters (stored together for faster join performance) and hush clusters
15.I've got about 3 questions on index clusters and none about hush clusters
16.Sysprivs and roles use WITH ADMIN OPTION, use WITH GRANT OPTION for object privs.
17.Revoke a GRANT...WITH ADMIN OPTION is not hierarchical and will not cascade, unlike WITH GRANT OPTION
18.Know how to calculate the size of the N nd extend. INITIAL, NEXT, NEXT := NEXT*(1+PCTINCREASE/100)...
19.PCTUSED is not valid for indexes; OPTIMAL is only valid for rollsegs; PCTINCREASE for rollsegs is 0 (cannot be set)
20.There are at least 3 questions about what will happen when PCTFREE/PCTUSED are increased/decreased
21.MAXTRANS applies to all blocks; INITRANS to new blocks only (23 bytes per freelist entry)
22.Run orapwd utility before setting REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE|SHARED; Grant OSDBA/OSOPER to users; Check V$PWFILE_USERS
23.DB_NAME is the only mandatory parm; DB_BLOCK_SIZE cannot change after db creation
24.Defaults: DB_BLOCK_SIZE=2K/ DB_BLOCK_BUFFERS=60/ SHARED_POOL_SIZE=3,500,000 bytes
25.Must have at least one control file and 2 log groups
26.Read consistency: readers do not block writers and writers do not block readers
AUDIT_TRAIL=DB uses SYS.AUD$ table, view via DBA_AUDIT_TRAIL
27.Use AUDIT SELECT for sequences
28.You need to set RESOURCE_LIMIT=TRUE for PROFILES (resource checking)
29.One can DROP from a READ ONLY ts

1Z0-014 - Oracle8: Performance Tuning Workshop

1.Tuning process is ITERATIVE and PROGRESSIVE
2.Many inserts/updates with OLTP, many table scans with DSS
3.By default the SYSTEM tablespace will be used for sorts, CHANGE IT!!!
4.SEP=Sort Extent Pool is in SGA, Sorts are done in user memory except with MTS it's in UGA
5.Use DBMS_APPLICATION_INFO to register and track modules/ created with dbmsutil.sql/ See V$SQLAREA and V$SESSION
6.OPTIMIZER_MODE is for instance, OPTIMIZER_GOAL is for session
7.RULE is based on rank/ COST is based on lowest relative cost/ COOSE goes to COST if stats exists
8.TKPROF: Logical reads = QUERY (logical reads in consistent mode) + CURRENT (logical reads in current mode)
9.V$SYSSTAT: Logical reads = consistent gets + db block gets
10.Tune table scans: DB_FILE_MULTIBLOCK_READ_COUNT=/ CACHE_SIZE_THRESHOLD=
Dict. row cache: V$ROWCACHE - getmisses/gets must be < 15%
11.Library cache: V$LIBRARYCACHE - pins/reloads <= 1% and GETHITRATIO > 0.90
12.DB Block cache: V$BH/V$CACHE - logical_reads/ (logical_reads + physical reads) must be > 80% (90% with RAW)
13.V$CACHE is usefull for Oracle Parallel Server
14.Set DB_BLOCK_LRU_LATCHES if you have misses in V$LATCH
15.If Redo log space requests <>0, increase LOG_BUFFER= with 5%
16.Latches can be WILLING-TO-WAIT (eg redo allocation) or NOWAIT (eg redo copy)
17.Oracle maintains all locks as ENQUEUES/ Deadlocks are resolved at statement level
18.Lock modes: RX=DML/ TM=table/ TX=transaction and rollseg/ RS=SELECT... FOR UPDATE/ SRX=DML and no SELECT FOR UPDATE/ UL=user lock/ S=prevents any DML
19.Index foreign key column on child table to prevent SHARE lock during DML on parent!!!
20.Use SID and Serial# in V$SESSION to kill a session
21.Impact of reducing DB_BLOCK_BUFFERS: Set DB_BLOCK_LRU_STATISTICS= and query V$KCBCBH
22.Impact if increasing DB_BLOCK_BUFFERS: Set DB_BLOCK_EXTENDED_LRU_STATISTICS= and query V$KCBCBH
23.To keep sorts in memory, increase SORT_AREA_SIZE
24.SORT_WRITE_BUFFERS (16k - 32k) * SORT_WRITE_BUFFER_SIZE (2-8) + SORT_AREA_SIZE
25.Any MTS parameter may be wrong, but if MTS_SERVICE=SID, you will get a dedicated server connection if shared cannot be established

1Z0-015 - Oracle8: Backup and recovery Workshop
1.Backups types: Image copies (operating system backups) or logical backups (imp/ exp)
2.Files to backup: select * from v$controlfile/v$datafile/v$logfile, init.ora and password file
3.NOARCHIVELOG mode is default, you need to switch to ARCHIVELOG to do online-backups and point-in-time recovery.
4.You can only switch log mode in MOUNT-state (STARTUP MOUNT). You need ALTER DATABASE privs to do this.
5.LOG_ARCHIVE_START=TRUE will start ARCH process
6.An on-line DB is backed up tablespace by tablespace. Use the ALTER TABLESPACE BEGIN BACKUP command (Not READ ONLY tablespaces!!!)
7.Exp/imp DIRECT=YES uses RECORDLENGTH= and not BUFFER=. Data written directly to TTC (Two task common buffer) and bypasses BUFFER CACHE
8.Use exp CONSISTENT=YES if you need to preserve integrity between tables.
9.INCTYPE=INCREMENTAL - objects changed since last export of any type/ INCTYPE=CUMULATIVE - obects changed since last cumulative export
10.You cannot roll forward after a logical recovery (ie apply redo log files after an import).
11.After DB structure changes (know when - 2-3 questions) do an ALTER DATABASE BACKUP CONTROLFILE...
12.Complete Recovery: DATABASE/ TABLESPACE/ DATAFILE based
13.Incomplete Recovery: TIME (YYYY-MM-DD:HH24:MI:SS)/ CANCEL/ CHANGE based
14.Incomplete recovery not possable on SYSTEM ts or ts with active rollsegs.
15.Be careful not to confuse CANCEL and CHANGED based recovery.
16.All datafiles must be restored for an incomplete recovery. Incomplete recovery is to a point in the past.
17.After incomplete recovery, do an OPEN RESETLOGS and take a backup.
18.If LOG_BLOCK_CHECKSUM=TRUE and checksum fails: ALTER DATABASE CLEAR LOGFILE...
19.Use DBVERIFY (dbv file=...) to check offline datafiles for structural damage (be careful, the training guide incorrectly states that both On-line and Off-line files can be checked)

1Z0-016 - Oracle8: Network Administration
1.The exam is easy, but take care of it, some answer is out of your image.
2.At chapter 1,2 and 3, the answer is ambigious. It is easy to lose your scores.