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原创 Linux操作系统 作者:oceanding 时间:2011-07-16 01:09:18 0 删除 编辑


  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,
  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$SYSSTAT: Logical reads = consistent gets + db block gets
  Dict. row cache: V$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
  23.To keep sorts in memory, increase 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 Worksho

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