Oracle Database 11g: Administration Workshop I

Mc lcBi 1: Tm Hiu Kin Trc Oracle Database2Mc tiu2Oracle Database2Kt ni n Server3Tng quan v kin trc Oracle Database4Instance: Cu hnh database6Kt ni vi Database Instance6Cu trc b nh Oracle Database7Shared pool9Database Buffer Cache11Rego Log Buffer12Large pool13Java pool v Streams pool14Program Global Area (PGA)15QUIZ16Kin trc x l (Process Architecture)18Cc Cu trc x l (Process Structure)19

Bi 1: Tm Hiu Kin Trc Oracle DatabaseMc tiuSau khi hon tt bi hc ny, bn c th: Lit k cc thnh phn kin trc c bn ca mt Oracle Database Gii thch kin trc b nh (memory structure) M t cc background process (tin trnh nn) Mi tng quan gia cu trc lu tr vt l v logic (logical & physical storage structure) M t thnh phn lu tr ASM

Mc tiuBi hc ny cung cp thng tin tng quan v kin trc ca Oracle Database. Bn s hc v kin trc vt l v logic cng vi nhiu thnh phn khc.

Oracle DatabaseH thng qun l c s d liu quan h Oracle (Oracle relational database management system RDBMS) cung cp cc gii phi m, ton din, hp nht qun l thng tin

Oracle DatabaseDatabase (c s d liu) l tp hp cc thng tin c x l nh mt n v (unit). Mc ch ca database l lu tr v truy xut thng tin c lin kt.C s d liu quan h Oracle (RDBMS) qun l mt cc hiu qu lng d liu ln trong mi trng h thng multiuser (nhiu ngi dng), do nhng user (ngi dng) c th ng thi truy cp cng mt d liu vo cng mt thi im. Vic ny c hon thnh trong khi hiu nng cung cp vn t mc cao. Cng mt thi im, n ngn chn cc truy xut cha xc thcng thi cung cp cc gii php hiu qu phc hi cc d liu hng.

Kt ni n Server

Minh ha kin trc a tngKt ni n ServerMt database user c th kt ni n server Oracle theo mt trong ba cch: User ng nhp vo h iu hnh ang chy Oracle instance (tm dch: thc th Oracle), v khi chy ng dng hoc cng c dng truy xut database trn h iu hnh . ng dn giao tip (communication pathway) c khi to s dng cc k thut giao tip lin tin trnh (interprocess) c sn trn h iu hnh ch. User s dng ng dng hoc cng c trn my tnh cc b (local computer) v kt ni thng qua mt h thng mng (network) vi my tnh chy Oracle Database. cch thc cu hnh ny (gi l client/server m hnh khch/ch), phn mm mng my tnh c s dng giao tip gia user v back-end server (tm dnh: server u sau). H thng kin trc c s d liu client/server gm c hai phn: mt front-end (tm dch: u trc) (client) v mt back-end (server) kt ni vi nhau thng qua mng my tnh. Phn mm mng c s dng giao tip gia user v Oracle server. Client (khch) l ng dng database to yu cu mt thao tc c thc thi trn database server. N yu cu, x l, v trnh by d liu c qun l bi server. Cc trm client c th c ti u cho cng vic ca chng. Ly v d, client c th khng cn dung lng cng ln, hay chng c th li th v kh nng ha. Thng thng, mt client l mt my tnh khc vi database server. Nhiu client c th chy tng tc ng thi trn mt server. Server chy phn mm Oracle Database v nm cc chc nng bt buc cho vic truy cp, chia s d liu ng thi. Server nhn v x l cc yu cu khi to t ng dng client. My tnh qun l server c th c ti u cho nhim v ca chng. Ly v d, mt my tnh server c th s hu dung lng cng ln cng vi vi x l tc cao. User truy cp v mt ng dng server thng qua mt cng c ( nh Trnh duyt web) trn my tnh cc b (client). Sau ng dng server thay mt cho client tng tc vi database u cui (back-end).Mt kin trc a tng thng thng gm nhngthnh phn di y: Mt client hay mt process ban u khi to thao tc Mt hoc nhiung dng server thi hnh tng phn thao tc. Mt ng dng server cha phn ln cc ng dng logic, cp quyn truy cp d liu cho client, v hon thnh cc yu cu truy vn, nh gim ti gnh nng cho database server. ng dng server c th trnh by mt giao din gia client v nhiu database server v c th cung cp mt mc h tr bo mt nht nh. Mt server cui hay database server lu tr hu ht cc d liu c s dng cho cc thao tcKin trc ny cho php s dng mt ng dng server lm nhng vic nh: Xc minh chng thc y quyn ca mt client (nh Trnh duyt web) Kt ni n mt Oracle Database server Thc thi cc thao tc yu cu t pha client

Tng quan v kin trc Oracle Database

Kin trc Oracle DatabaseC ba cu trc (structure) c bn trong kin trc ca mt server Oracle Database: cu trc b nh (memory structures), cu trc x l (process structures), v cu trc lu tr (storage structures). Mt h thng Oracle Database c bn bao gm mt Oracle Database v mt Oracle instance (tm dch: thc th Oracle).Database bao gm c cu trc vt l (physic structure) v cu trc logic (logic structure). Do cu trc vt l v logic l ring bit, vng lu tr vt l ca d liu c th c qun l m khng nh hng n vic truy cp vo cu trc lu tr logic.Khi nim instance bao gm cu trc b nh v cc background processes (tin trnh nn) c lin kt vi instance . Mi ln mt instance khi ng, mt vng b nh dng chung c gi l System Global Area (SGA) (tm dnh: vng lu tr h thng ton cc) c cp pht v cc background process c khi ng. Process (tin trnh) l cc cng vic hot ng trong b nh my tnh. Mt process c nh ngha nh l mt lung iu khin (thread of control) hay k thut chy mt chui cc thao tc trong mt h iu hnh. Sau khi khi ng mt database instance (thc th c s d liu), phn mm Oracle kt hp mt instance vi mt database ring bit. Vic ny gi l mounting the database (tm dch: rp khung c s d liu). Lc ny database sn sng c m, to kh nng truy cp cho cc user c xc thc.Ghi ch: Chc nng Qun l lu tr t ng (Automatic Storage Management - ASM) s dng quan im mt instance gm thnh phn b nh v x l, nhng khng ng vi mt database ring bit.

Instance: Cu hnh database

Instance: Cu hnh databaseMi database instance (thc th c s d liu) ng vi mt v ch mt database. Nu c nhiu database trn cng mt server th s c nhiu database instance tng ng vi mi database. Mt database instance khng th dng chung. Mt c s d liu RAC (Real Application Cluster, tm dch: Tp hp ng dng thc) thng c nhiu instance trn cc server ring cho cc database ging nhau dng chung. (shared database). Trong m hnh ny, database ging nhau c lin kt vi mi RAC instance (thc th RAC), p ng yu cu ch c mt database c lin kt vi mt instance.

Kt ni vi Database Instance Kt ni (connection): Lin kt gia user process (tin trnh ngi dng) v instance Phin (session): l mt kt ni ring bit gia user vi instance thng qua user process

Kt ni n mt Database instanceKt ni v phin c mi quan h kh tng ng nhau i vi mt user process (tin trnh ngi dng) nhng chng c ngha rt khc nhau.Mt kt ni l mt ng dn giao tip (communication pathway) gia user process v Oracle Database instance. Mt ng dn giao tip c khi to bng vic s dng cc k thut giao tip lin tin trnh c sn (trn my tnh chy c user process v Oracle Database) hoc phn mm my tnh (khi cc my tnh khc nhau chy ng dng database v Oracle Database, giao tip vi nhau thng qua mng my tnh).Mt phin tng trng cho giai on user ng nhp vo Database instance. V d: khi user khi chy SQL*Plus, user phi cung cp ng username v password, v sau mt phin c khi to cho user . Mt phin ko di t lc user kt ni n lc user ngt kt ni hoc ng ng dng database.Nhiu phin c th c khi to vo kt thc ng thido user n l s dng mt username. V d, mt user vi username/password l HR/HR c th kt ni vi cng mt database instance nhiu ln.

Cu trc b nh Oracle Database

Cu trc b nh Oracle DatabaseOracle Database to v s dng cc cu trc b nh cho nhiu mc ch. V d, b nh dng lu tr m lnh chng trnh ang c chy, d liu dng chung gia nhng user, v vng d liu ring t cho mi user kt ni.C hai cu trc b nh c bn c lin kt vi mt instance: System Global Area (SGA) (tm dch: vng h thng ton cc): nhm cc cu trc b nh dng chung, c hiu nh l thnh phn SGA, cha d liu v thng tin iu khin cho mt Oracle Database instance. SGA c dng chung bi tt c server v cc background process. Cc v d v d liu c lu tr trong SGA gm cc khi d liu c lu m (cached data blocks) v vng SQL dng chung (shared SQL area). Program Global Area (PGA) (tm dch: vng chng trnh ton cc): vng b nh cha thng tin iu khin v d liu cho mt server hoc mt background process. PGA l b nh khng c chia s c to bi Oracle Database khi mt server hoc mt background process khi ng. Vic truy cp n PGA ch c th c thc thi bi server process (tin trnh server). Mi server process v background process c PGA ca ring n.SGA l vng b nh cha d liu v thng tin iu khin ca instance. SGA bao gm cc cu trc sau: Shared pool: Vng nh m nhiu cu trc c chia s gia nhiu user Database buffer cache: Vng nh m cha khi d liu trch t database KEEP buffer pool: Mt loi vng nh database m chuyn dng iu chnh vic bo ton khi d liu trong b nh trong sut nhiu chu k ko di RECYCLE buffer pool: Mt vng nh database m chuyn dng iu chnh vic phc hi hoc xa cc khi d liu ra khi b nh mt cch nhanh chng nK buffer cache: Mt trong nhng vng nh database m chuyn dng c th k gi thng tin khch c khi d liu (block size) khc th no vi kch thc mc nh (default) ca khi d liu Large pool: Vng nh m rng cung cp mt vng b nh ln cp pht cho cc tin trnh ln, nh thao tc Oracle backup and recovery (tm dch: sao lu vo phc hi), v I/O server processes ( tm dch: cc tin trnh server Nhp/Xut) Java pool: S dng cho tt c cc phin-Java-code-t-th (session-specific Java code) v d liu trong My o Java (Java Virtual Machine JVM) Stream pool: c s dng bi Oracle Stream lu thng tin yu cu do capture v apply.Khi bn khi chy instance bng cch s dng Enterprise Manager hoc SQL*Plus, s lng b nh c cp pht cho PGA c hin th.Program Global Area (PGA) l vng nh cha d liu v thng tin iu khin cho mi server process. Mt Oracle server process phc v mt yu cu ca client. Mi server process c PGA ring ca n c cp pht khi server process khi chy. Vic truy cp n PGA ch c th c thc thi bi server process, v PGA ch c c v vit bng m lnh Oracle hot ng trn chnh n. PGA c chia l hai vng chnh: stack space v user global area (UGA).Vi h tng kin trc ng (dynamic infrastructure), kch thc ca database buffer cache, shared pool, large pool, Java pool, v Streams pool c th thay i m k phi tt (shutting down) instance i.C d liu Oracle to ra cc tham s (parameters) xy dng v qun l cu trc b nh. Cch n gin nht qun l cu trc b nh l cho php database t ng qun l v thng bo li cho bn. lm nh vy (trn hu ht cc nn tng), bn ch cn phi t ra tham s ch tiu cho kch c b nh (target memory size) (MEMORY_TARGET) v tham s kch c b nh ti a (MEMORY_MAX_TARGET).

Shared pool L mt phn ca SGA Bao gm: Lybrary cache (Vng nh m th vin) Shared SQL Area (Vng SQL dng chung) Control structure (Cu trc iu khin)

Shared poolShared pool l mt phn ca SGA gm c library cache, data dictionary cache, SQL querry result cache, PL/SQL function result cache, vng nh m thi hnh cch lnh song song, v cc cu trc iu khin (control structure).Data dictionary (tm dch: t in d liu) l mt tp hp mt bng d liu cho thy thng tin tham chiu v database, cu trc v cc user ca n. Oracle Database truy cp vo data dictionary nhiu ln trong sut qu trnh phn tch (parsing) cu lnh SQL. Vic truy cp ny cn thit cho chui thao tc lin tc ca Oracle Database.Data dictionary c truy cp thng xuyn bi Oracle Database, do vy c 2 vng nh c thit k cho vic lu gi data dictionary. Mt vng gi l data dictionary cache (vng nh t in d liu), c hiu nh vng nh dng (row cache) bi v chng lu gi d dng dng (row) thay cho dng m (buffer) (tc l lu gi ton b cc khi d liu blocks of data). Vng lu gi data dictionary cn li trong b nh l library cache (vng nh th vin). Tt c cc user process chia s hai vng nh ny cho vic truy xut thng tin ca data dictionary.Oracle Database t cho mi cu lnh SQL chy vi vng SQL dng chung (shared SQL area) (cng nh cc vng SQL ring t (private SQL area) c nm gi trong PGA). Oracle Database nhn bit hai user thi hnh cng cu lnh ging nhau v s dng li vng SQL dng chung cho cc user .Vng SQL dng chung cha cy phn tch (parse tree) v thi hnh cc mc tiu do cc cu lnh SQL ban hnh. Oracle Database tit kim b nh bng vic dng vng SQL dng chung mt ln cho nhiu cu lnh SQL chy nhiu ln, vic ny thng din ra khi nhiu user chy ng dng ging nhau.Khi mt cu lnh SQL mi c phn tch, Oracle Database cp pht b nh t shared pool lu tr vng SQL dng chung. Kch thc b nh ph thuc vo phc tp ca cu lnh.Oracle Database x l cc n v chng trnh PL/SQL - PL/SQL program unit (cc hm\procedure, hm\function, gi\package, gi tin nc danh\anonymous block, v cc trigger c s d liu\database trigger) vi cch thc kh ging vi vic x l tng cu lnh SQL ring l. Oracle Database cp pht mt vng dng chung gi mu phn tch, bin dch ca n v chng trnh. Oracle Database cp pht mt vng ring t gi cc gi tr tng ng vi cc phin lm vic chy trn n v chng trnh, bao gm cc gi tr cc b, ton cc, v gi tr gi (cng c th hiu l mt gi instance) cng vi d liu m (buffer) thc thi cu lnh SQL. Nu c nhiu hn mt user cng chy ging mt n v chng trnh, th ch c mt vng dng chung c s dng cho ton b user, trong khi ton b user ny c nhng phin bn ring thuc vng SQL ring t, nm gi cc gi tr tng ng vi cc phin ca h.Cc cu lnh SQL ring l cha trong mt n v chng trnh PL/SQL c x l ging nh cc cu lnh khc. Mc d bn gc ca chng nm trong n v chng trnh PL/SQL, nhng cu lnh ny vn dng mt vng dng chung gi php bit din cc mu phn tch, v mt vng ring t cho mi phin chy trn cu lnh .SQL querry result cache (vng nh kt qu truy vn) v PL/SQL function result cache (vng nh kt qu hm) l cc cu trc mi trong Oracle Database 11g. Chng chia s chung h tng, biu th trong cng mt hiu sut ng (dynamic performance (V$) views), v qun tr da trn cc gi cung ng(supplied package) ging nhau.Kt qu ca truy vn v cc phn on truy vn (query fragment) c th c lu nhanh ti vng nh SQL query result cache. Database c th s dng cache result tr li cc lnh thc thi truy vn v cc phn on truy vn trong tng lai. Bi v tr v kt qu t cache result nhanh hn vic chy lnh truy vn, vic chy li truy vn thng xuyn s c ci thin ng k v tc khi kt qu truy vn c lu m (cached).PL/SQL function thnh thong c dng tr v kt qu php tnh c input l kt qu truy vn ca mt hoc vo hm no . Trong mt s trng hp, nhng truy vn ny truy cp d liu rt t khi b bin i so vi tn s gi hm. Bn c th km theo mt c php trong m ngun ca PL/SQL function yu cu lu m kt qu trong PL/SQL function result cache ( m bo tnh ng n) v vng nh (cache) s c xa khi cc bng nm trong danh sch bng DML ht hn.Fixed area ca shared pool ng vai tr l vng khi ng trc ht ca SGA. N rt nh so vi kch c chun ca shared pool hay SGA.

Database Buffer Cache L mt phn ca SGA Lu gi bn copy khi d liu (data blocks) c c t file d liu (data files) c chia s cho tt c cc user cng thi im.

Database Buffer CacheDatabase buffer cache (vng nh m d liu) l mt phn ca SGA lu gi cc khi nh* c c t file d liu hoc cc kin trc ng tha m hnh ng nht. Tt c user ng thi c kt ni vi mt instance v truy cp chung database buffer cache./* by phamdinhvutien@gmail.com nh y khng phi l theo ngha l hnh nh pictures m l cc file nh image, tc l mt bn lu d liu nguyn dng, nu cc bn tip xc vi cc file c nh dng l iso, cdd, img, bin (y l cc nh dng nh thng dng) tc l cc bn phn no hiu c khi nim nh y l g ri*/Ti thi im u tin user process Oracle Database yu cu cc mu d liu chi tit, n tm d liu trong database buffer cache. Nu process tm thy d liu ang sn sng trong vng nh (cache hit), n c th c d liu trc tip t b nh. Nu process khng th tm thy d liu trong vng nh (cache miss), n phi chp khi d liu t file d liu trn cng vo trong vng nh m trc khi truy cp d liu. Vic truy cp t cache hit nhanh hn l truy cp t cache miss.Vng m trong b nh c qun l bi mt thut ton phc tp dng tp hp cc danh sch dng gn y ti thiu (least recently used - LRU) v b m (touch count). LRU gip m bo cc khi d liu thng dng nht c gi trong b nh gim thiu mc truy cp vo cng.KEEP buffer pool v RECYCLE buffer pool c s dng nh mt vng b nh iu chnh chuyn bit. KEEP buffer pool c thit k bo ton vng nh m trong b nh lu hn thut ton LRU thng gi chng. RECYCLE buffer pool c thit k xa vng nh m trong b nh lu hn LRU thng lm.Cc vng nh m b sung c th c cu hnh gi cc khi d liu c kch thc khc vi kch thc mc nh.

Rego Log Buffer L mt b m trn (circular buffer) trong SGA Gi thng tin v nhng thay i trn c s d liu. Bao gm cc mc hon tc (redo entries) c thng tin khi phc cc thay i do cc thao tc nh DML v DDL

Redo Log Buffer (Vng m nht k hon tc)Redo log buffer l b m trn (circular buffer) trong SGA gi thng tin v nhng thay i trn database. Thng tin ny c lu trong mc hon tc (redo entries). Mc hon tc cha nhng thng tin cn thit kin trc li (reconstruct) hoc hon tc (redo) trn database do cc thao tc DML, DDL, hay cc thao tc ni b. Mc hon tc c s dng khi phc d liu nu cn thit.Trong khi server process thay i vng nh m, mc hon tc c khi to v ghi ln bi redo log buffer trong SGA. Mc hon tc dng cc khong ni tip, lin tc trong vng nh m. Log writer background process ghi li redo log buffer ln file nht k hon tc (redo log) trn cng.

Large pool Chun b b nh ln cp pht cho Cc phin b nh cho cc sever dng chung v Oracle XA interface I/O server processes Thao tc Oracle Database backup v restore

Large poolDatabase Administrator c th cu hnh mt vng nh ty chn gi l large pool chun bi mt b nh ln cp pht cho: Cc phin b nh cho cc server dng chung v Oracle XA interface (c s dng cc giao dch tng tc vi nhiu database) I/O server processes (tin trnh server Nhp/Xut) Thao tc Oracle Database backup v restore (sao lu v phc hi) Cc thao tc truy vn song song (Paralell Query) Bng lu tr b nh Advanced QueuingBng vic cp pht phin b nh t large pool cho cc server dng chung, Oracle XA, hay vng m truy vn song song, Oracle Database c th dng shared pool l vng nh m chnh cho cc SQL dng chung, trnh hin tng trn b nh do phi thu hp vng SQL dng chung.Bn cnh , b nh cho cc thao tc Oracle Database backup and restore, I/O server processes v cho b m song song c cp pht cho vng m vo khong vi trm kylobites. Large pool p ng tt hn shared pool i vi cc yu cu cn b nh ln.Large pool khng b qun l bi danh sch LRU.

Java pool v Streams pool Java pool c dng lu tr tt c cc phin java-code v d liu trong JVM Streams pool c s dng duy bi Oracle Streams cho vic: Lu tr cc chui thng tin vng m Cung cp b nh cho cc Oracle Streams process

Java pool v Stream poolB nh Java pool c dng lu tr tt c cc phin java code v d liu trong JVM. Java pool c s dng bng nhiu cch khc nhau, ph thuc vo ch (mode) ang chy ca Oracle Database.Stream pool c ch c s dng bi Oracle Streams. Stream pool lu tr cc chui thng tin vng m, n cung cp b nh cho Oracle Streams theo di v p dng cc process.Tr khi bn cu hnh ring cho n, thng thng kich c ca Stream pool lc bt u l khng. Kch thc ca Stream pool tng ln nh mong mun khi n c s dng b Oracle Streams.Ghi ch: Thng tin v vn lp trnh Java v Oracle Streams nm ngoi phm vi ca lp hc ny.

Program Global Area (PGA)

Program Global Area (PGA)Program Global Area(PGA) l vng nh ring t cha thng tin iu khin v d liu cho mt server process. Mt server process c mt PGA ring. Ch c server process c truy cp n bng m lnh Oracle vi t cch l process . M lnh ca nh pht trin khng c php can thip.Mi PGA c mt Stack space (tm dch: khong ngn xp). Trong mi trng server c lp, mi user kt ni vi database c mt server process ring. i vi loi kt ni ny, PGA gm mt phn b nh gi l user global area (UGA) (tm dch: vng ngi dng ton cc). UGA l tp hp nhng thnh phn di y: Cursor area (Vng con tr) lu thng tin thi gian chy trn con tr User session data storage area (Vng lu tr phin d liu ngi dng) iu khin thng tin v cc phin lm vic SQL working area (Vng lm vic vi SQL) x l cc cu lnh SQL bao gm: Sort area (Vng lc) cho cc hm sp xp d liu nh ORDER BY v GROUP BY Hash area (Vng hash /*khi nim hash hi di dng, cc bn t tm hiu*/) thc thi cc hash join table (trn bng) Create bitmap area (Vng to bitmap) dng to cc bng bitmap cho cc nh kho d liu (data warehouse) Bitmap merge area (Vng trn bitmap) dng gii quyt cc phng n thc thi bng bitmapTrong mi trng server dng chung, nhiu user pha client chia s server process. ch ny, UGA c di chuyn vo SGA (shared pool hoc large pool nu cu hnh trc) v PGA ch cn li stack space.

QUIZ

Vng nh cha d liu v thng tin iu khin cho mt server process hoc background process c gi l:1. Share Pool2. PGA3. Vng nh m (Buffer Cache)4. User session data (phin d liu ngi dng)

Tr li: 2

Ci g c c trong vng nh m database (Database buffer cache) t file d liu?1. Hng (Rows)2. S thay i (Changes)3. Khi (Block)4. SQL

Tr li: 3

Kin trc x l (Process Architecture) User process (Tin trnh ngi dng) L ng dng hoc cng c kt ni n Oracle Database Database process (Tin trnh c s d liu) Server process (Tin trnh server): Kt ni vi Oracle instance v c khi ng khi mt user khi to phin lm vic Background process (Tin trnh nn): c khi ng khi mt Oracle instance c khi ng. Daemon/Application process: Networking listener Grid infrastructure daemon (h tng li)

Kin trc x l (Process Architecture)Process trong mt h thng Oracle database c th c chia lm ba nhm chnh: User process chy ng dng hoc cng c m lnh Oracle Cc Oracle Database process chy m lnh Oracle database server (bao gm cc server process v background process) Oracle daemon process v application process khng ch nh cho mt database n lKhi mt user chy mt chng trnh ng dng hoc mt cng c Oracle nh SQL*Plus, cm t user process c dng ch ng dng ca user. User process c th nm hoc khng nm trn my tnh database server. Oracle Database cng to ra mt server process thi hnh cc lnh do user process a ra. Ngoi ra, Oracle server cng c nhng background process cho mt instance tng tc vi nhng instance khc vi h iu hnh qun l cu trc b nh, thc thi cc thao tc nhp xut khng ng b ghi d liu vo cng, v thc thi cc yu cu cng vic khc.Cu trc x l thay i ty theo cc cch cu hnh Oracle Database khc nhau, da trn h iu hnh v la chn cc ty chn ca Oracle Database. M lnh cho cc user kt ni c th c cu hnh l mt server c lp hoc server dng chung. Server c lp (Dedicated server): i vi mi phin, ng dng database chy bi user process c phc v bi mt server process c lp thc thi m lnh Oracle database server. Server dng chung (Shared server): Loi b nhu cu mt server process c lp cho mi kt ni. Mt b phn gi i (dispatcher) gi nhiu yu cu cc phin mng nhn c cho mt phn server process dng chung. Mt server process dng chung phc v nhiu yu cu pha client.

Cc Cu trc x l (Process Structure)

Cc Cu trc x l (Process Structures)Server Process (Tin trnh server)Oracle Database to ra cc server process x l cc yu cu t pha cc user process kt ni n instance. User process thay mt cho ng dng hoc cng c kt ni n Oracle database./* by phamdinhvutien@gmail.com Oracle Database v Oracle database? C th t u n gi c nhng ln bn dch ghi l Oracle database thay v Oracle Database, khng phi ti li vit hoa m l do bn gc ting anh ghi nh vy. Cc bn c th hiu l Oracle Database y ch phn mm Oracle Database 11g, cn Oracle database ch c s d liu m bn to trn my tnh chy phn mm Oracle Database */User process c th cng nm trn my tnh cha Oracle database, hoc chng nm trn mt client t xa v thng qua mt mng my tnh kt ni ti Oracle database. Trc tin user process kt ni vi mt listener process, cng l process khi to mt server process trong mt mi trng c lp.Cc server process c to ra da trn ng dng ca user c th thc thi mt hoc mt nhiu th di y: Phn tch v chy cc cu lnh SQL nhn c t ng dng c cc khi d liu (data block) cn thit t file d liu trn a cng vo trong database buffer dng chung ca SGA (nu khi d liu khng c sn trn SGA) Tr v kt qu theo cch m ng dng c th x l c thng tin.Background process (Tin trnh nn) ti u ha h thng v thch nghi vi nhiu user, mt multiprocess (chui a tin trnh) ca h thng Oracle Database dng mt vi Oracle Database proccess ph gi l background process. Mt Oracle Database instance c th c nhiu background processCc background process thng thy trong mi trng non-RAC, non-ASM gm cc process di y: Database writer process (DBWn) (tin trnh ghi d liu) Log writer process (LGWR) (tin trnh ghi nht k) Checkpoint process (CKPT) (tin trnh nh du) System monitor process (SMON) (tin trnh gim st h thng) Process monitor process (PMON) (tin trnh gim st tin trnh) Recoverer process (RECO) (tin trnh khi phc) Job queue coordinator (CJQ0) (iu hp chi cng vic) Job slave processes (Jnnn) (cc tin trinh phc v cng vic) Archiver processes (ARCn) (cc tin trnh lu tr) Queue monitor processes (QMNn) (cc tin trnh gim st chui)Cc background process khc c th c tm thy trong mc cu hnh nng cao nh RAC. Xem mc V$BGPROCESS view bit thm thng tin v cc background process.Mt vi background process c to mt cch t ng khi mt instance khi ng, s cn li c khi ng theo yu cu.Cc cu trc x l khc khng thuc v mt database n l, m c dng chung cho nhiu database trn mt server chung. Grid Infrastructure (h tng li) v networking process (tin trnh mng) ri vo loi ny.Oracle Grid Infrastructure process trn h thng Linux v Unix gm c: ohasd: Oracle High Availability Service daemon chu trch nhim khi ng Oracle Clusterware process ocssd: Cluster Synchronization Service daemon diskmon: Disk Monitor daemon chu trch nhim lp ro input v output cho HP Oracle Exadata Storage Server cssdagent: Khi ng, dng v kim tra tnh trng ca CSS daemon, ocssd oraagent: M rng clusterware h tr cc yu cu Oracle-chuyn-bit v cc ngun phc tp orarootagent: mt tin trnh tc nhn Oracle chuyn dng gip qun l ti nguyn s hu ca root, nh l mng my tnh.Ghi ch: bit thm thng tin v danh sch cc background process, vui lng tra cu mc ph lc Oracle Background Processes trong kha hc ny hoc mc hng dn Oracle Database Reference.Page 20