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    RBOPath6:HashClusterKey
    RBOPath7:IndexedClusterKey
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    RBOPath9:Single-ColumnIndexes
    RBOPath10:BoundedRangeSearchonIndexedColumns
    RBOPath11:UnboundedRangeSearchonIndexedColumns
    RBOPath12:SortMergeJoin
    RBOPath13:MAXorMINofIndexedColumn
    RBOPath14:ORDERBYonIndexedColumn
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    ¦æ.¦E¤¤¬Ý¨ì.¦s¨ú¤èªk¡A¦p³q.¯Á¤Þ¬d..Õu¡C
    ¨Ï¥ÎROWID¦s¨úªº¤èªk¡G
    SQL>explainplanforselect*fromdeptwhererowid='AAAAyGAADAAAAATAAF';
    QueryPlan
    ------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    TABLEACCESSBYROWIDDEPT[ANALYZED]
    
    3¡^¯Á¤Þ.´y¡]IndexScan©Îindexlookup¡^
    §Ú.¥ý³q.index¬d§ä¨ì.Õu..ªºrowid­È(.¤_«D°ß¤@¯Á¤Þ¥i¯àªð¦^¦h.rowid­È)¡A
    µM¦Z®ÚÕurowidª½±µ.ªí¤¤±o¨ì¨ãÊ^ªº.Õu¡A.Ïú¬d§ä¤è¦¡..¯Á¤Þ.´y©Î¯Á¤Þ¬d§ä(index
    lookup)¡C¤@.rowid°ß¤@ªºªí¥Ü¤@¦æ.Õu¡A.¦æ..ªº.Õu.¬O³q.¤@¦¸i/o±o¨ìªº¡A¦b¦¹
    ±¡.¤U.¦¸i/o¥u..¨ú¤@..Õu..¡C
    ¦b¯Á¤Þ¤¤¡A°£¤F¦s.¨C.¯Á¤Þªº­È¥~¡A¯Á¤Þ.¦s.¨ã¦³¦¹­Èªº¦æ..ªºROWID­È¡C¯Á
    ¤Þ.´y¥i¥H¥Ñ2¨B.¦¨¡G(1).´y¯Á¤Þ±o¨ì..ªºrowid­È¡C(2)³q.§ä¨ìªºrowid.ªí¤¤
    .¥X¨ãÊ^ªº.Õu¡C¨C¨B³£¬O..ªº¤@¦¸I/O¡A¦ý¬O.¤_¯Á¤Þ¡A¥Ñ¤_.±`¨Ï¥Î¡A.¤j¦h.³£¤w
    .CACHE¨ì.¦s¤¤¡A©Ò¥H²Ä1¨BªºI/O.±`¬O..I/O¡A§Y.Õu¥i¥H..¦s¤¤±o¨ì¡C¦ý¬O
    .¤_²Ä2¨B..¡A¦pªGªí¤ñ.¤j¡A.¨ä.Õu¤£¥i¯à¥þ¦b.¦s¤¤¡A©Ò¥H¨äI/O«Ü¦³¥i¯à¬Oª«²z
    I/O¡A.¬O¤@.Éó±ñ¾Þ§@¡A¬Û...I/O..¡A¬OÌå¨ä...ªº¡C©Ò¥H¦pªG¦h¤jªí.¦æ¯Á¤Þ
    .´y¡A¨ú¥Xªº.Õu¦pªG¤j¤_.¶qªº5%--10%¡A¨Ï¥Î¯Á¤Þ.´y.®Ä²v¤U­°«Ü¦h¡C
    ¦p¤U¦C©Ò¥Ü¡G
    SQL>explainplanforselectempno,enamefromempwhereempno=10;
    QueryPlan
    ------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    TABLEACCESSBYROWIDEMP[ANALYZED]
    INDEXUNIQUESCANEMP_I1
    ª`·NTABLEACCESSBYROWIDEMP³¡¤À¡A.ªí©ú.¤£¬O³q.FTS¦s¨ú¸ô...
    .Õu¡A¦Ó¬O³q.rowidlookup¦s¨ú¸ô....Õuªº¡C¦b¦¹¨Ò¤¤¡A©Ò»Ý­nªºrowid¬O¥Ñ¤_¦b¯Á
    ¤Þ¬d§äempno¦Cªº­È±o¨ìªº¡A.Ïú¤è¦¡¬OINDEXUNIQUESCAN¬d§ä¡A¦Z­±.¤©¤¶.¡A
    EMP_I1.¨Ï¥Îªº.¦æ¯Á¤Þ¬d§äªº¯Á¤Þ¦W¦r¡C
    
    ¦ý¬O¦pªG¬d.ªº.Õu¯à¥þ¦b¯Á¤Þ¤¤§ä¨ì¡A´N¥i¥HÁקK.¦æ²Ä2¨B¾Þ§@¡AÁקK¤F¤£¥²­n
    ªºI/O¡A¦¹.§Y¨Ï³q.¯Á¤Þ.´y¨ú¥Xªº.Õu¤ñ.¦h¡A®Ä²v.¬O«Ü°ªªº¡A¦]..¥u.¦b¯Á¤Þ¤¤
    .¨ú¡C©Ò¥H¤W­±§Ú¦b¤¶.°ò¤_..ªºÉ¬¤Æ¾¹.¡A¨Ï¥Î¤Fselectcount(id)from
    SWD_BILLDETAILwherecn<'6'¡A¦Ó.¦³¨Ï¥Îselectcount(cn)fromSWD_BILLDETAIL
    wherecn<'6'¡C¦].¦b..±¡.¤¤¡A¥u¬d.³Q¯Á¤Þ¦Cªº­Èªº±¡.Ìå.¤Ö¡A©Ò¥H¡A¦pªG§Ú¦b¬d
    .¤¤¨Ï¥Îcount(cn)¡A.¤£¨ã¦³¥Nªí©Ê¡C
    
    SQL>explainplanforselectempnofromempwhereempno=10;--¥u¬d.empno¦C­È
    QueryPlan
    ------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    INDEXUNIQUESCANEMP_I1
    
    .¤@¨B.¡A¦pªGsql.¥y¤¤.¯Á¤Þ¦C.¦æ±Æ§Ç¡A¦].¯Á¤Þ¤w..¥ý±Æ§Ç¦n¤F¡A©Ò¥H¦b
    .¦æ.¦E¤¤¤£»Ý­n¦A.¯Á¤Þ¦C.¦æ±Æ§Ç
    SQL>explainplanforselectempno,enamefromemp
    whereempno>7876orderbyempno;
    QueryPlan
    --------------------------------------------------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    TABLEACCESSBYROWIDEMP[ANALYZED]
    INDEXRANGESCANEMP_I1[ANALYZED]
    ...¨Ò¤l¤¤¥i¥H¬Ý¨ì¡G¦].¯Á¤Þ¬O¤w.±Æ§Ç¤Fªº¡A©Ò¥H.«ö·Ó¯Á¤Þªº.§Ç¬d.¥X²Å
    ¦X.¥óªº¦æ¡A¦]¦¹ÁקK¤F.¤@¨B±Æ§Ç¾Þ§@¡C
    
    ®ÚÕu¯Á¤Þªº.«¬ÉOwhere­­¨î.¥óªº¤£¦P¡A¦³4Ïú.«¬ªº¯Á¤Þ.´y¡G
    ¯Á¤Þ°ß¤@.´y(indexuniquescan)
    ¯Á¤Þ­S..´y(indexrangescan)
    ¯Á¤Þ¥þ.´y(indexfullscan)
    ¯Á¤Þ§Ö³t.´y(indexfastfullscan)
    
    (1)¯Á¤Þ°ß¤@.´y(indexuniquescan)
    ³q.°ß¤@¯Á¤Þ¬d§ä¤@..­È.±`ªð¦^..ROWID¡C¦pªG.°ß¤@¯Á¤Þ¦³¦h.¦C.¦¨
    (§Y.¦X¯Á¤Þ)¡A.¦Ü¤Ö­n¦³.¦X¯Á¤Þªº¤Þ.¦C.ÉO¨ì.¬d.¤¤¡A¦p.«Ø¤@.¯Á¤Þ¡Gcreate
    indexidx_testonemp(ename,deptno,loc)¡C.selectenamefromempwhere
    ename=¡¥JACK¡¦anddeptno=¡¥DEV¡¦.¥y¥i¥H¨Ï¥Î.¯Á¤Þ¡C¦pªG..¥y¥uªð¦^¤@¦æ¡A
    .¦s¨ú¤èªk..¯Á¤Þ°ß¤@.´y¡C¦Óselectenamefromempwheredeptno=¡¥DEV¡¦.
    ¥y.¤£.¨Ï¥Î.¯Á¤Þ¡A¦].where¤l¥yÏú.¦³¤Þ.¦C¡C¦pªG¦s¦bUNIQUE©Î
    PRIMARYKEY.§ô¡]¥¦«O.¤F.¥y¥u¦s¨ú.¦æ¡^ªº.¡AOracle.±`..°ß¤@©Ê.´y¡C
    ¨Ï¥Î°ß¤@©Ê.§ôªº¨Ò¤l¡G
    SQL>explainplanfor
    selectempno,enamefromempwhereempno=10;
    QueryPlan
    ------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    TABLEACCESSBYROWIDEMP[ANALYZED]
    INDEXUNIQUESCANEMP_I1
    
    (2)¯Á¤Þ­S..´y(indexrangescan)
    ¨Ï¥Î¤@.¯Á¤Þ¦s¨ú¦h¦æ.Õu¡A¦P¤W­±¤@.¡A¦pªG¯Á¤Þ¬O.¦X¯Á¤Þ¡A¦p(1)©Ò¥Ü¡A¦Ó
    ¥Bselectenamefromempwhereename=¡¥JACK¡¦anddeptno=¡¥DEV¡¦.¥yªð¦^¦h¦æ
    .Õu¡A.µM..¥y.¬O¨Ï¥Î..¦X¯Á¤Þ.¦æ¬d.¡A¥i¦¹.ªº¦s¨ú¤èªk..¯Á¤Þ­S..
    ´y¡C¦b°ß¤@¯Á¤Þ¤W¨Ï¥Î¯Á¤Þ­S..´yªº¨å«¬±¡.¤U¬O¦b..(where­­¨î.¥ó)¤¤¨Ï¥Î
    ¤F­S.¾Þ§@²Å(¦p>¡B<¡B<>¡B>=¡B<=¡Bbetween)
    ¨Ï¥Î¯Á¤Þ­S..´yªº¨Ò¤l¡G
    SQL>explainplanforselectempno,enamefromemp
    whereempno>7876orderbyempno;
    QueryPlan
    --------------------------------------------------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    TABLEACCESSBYROWIDEMP[ANALYZ, ED]
    INDEXRANGESCANEMP_I1[ANALYZED]
    
    ¦b«D°ß¤@¯Á¤Þ¤W¡A..col=5¥i¯àªð¦^¦h¦æ.Õu¡A©Ò¥H¦b«D°ß¤@¯Á¤Þ¤W³£¨Ï¥Î¯Á¤Þ­S
    ..´y¡C
    ¨Ï¥Îindexrangscanªº3Ïú±¡.¡G
    (a)¦b°ß¤@¯Á¤Þ¦C¤W¨Ï¥Î¤Frange¾Þ§@²Å(><<>>=<=between)
    (b)¦b.¦X¯Á¤Þ¤W¡A¥u¨Ï¥Î³¡¤À¦C.¦æ¬d.¡A.­P¬d.¥X¦h¦æ
    (c).«D°ß¤@¯Á¤Þ¦C¤W.¦æªº¥ô¦ó¬d.¡C
    
    (3)¯Á¤Þ¥þ.´y(indexfullscan)
    ÉO¥þªí.´y..¡A¤]¦³¬Û.ªº¥þ¯Á¤Þ.´y¡C¦b¬Y¨Ç±¡.¤U¡A¥i¯à.¦æ¥þ¯Á¤Þ.´y¦Ó
    ¤£¬O­S..´y¡A»Ý­nª`·Nªº¬O¥þ¯Á¤Þ.´y¥u¦bCBO¼Ò¦¡¤U¤~¦³®Ä¡CCBO®ÚÕu...
    ­È±oª¾.¦æ¥þ¯Á¤Þ.´y¤ñ.¦æ¥þªí.´y§ó¦³®Ä.¡A¤~.¦æ¥þ¯Á¤Þ.´y¡A¦Ó¥B¦¹.¬d.
    ¥Xªº.Õu³£¥²..¯Á¤Þ¤¤¥i¥Hª½±µ±o¨ì¡C
    ¥þ¯Á¤Þ.´yªº¨Ò¤l¡G
    AnIndexfullscanwillnotperformsingleblocki/o'sandsoitmayprovetobe
    inefficient.
    
    e.g.
    IndexBE_IXisaconcatenatedindexonbig_emp(empno,ename)
    
    SQL>explainplanforselectempno,enamefrombig_emporderbyempno,ename;
    QueryPlan
    --------------------------------------------------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=26
    INDEXFULLSCANBE_IX[ANALYZED]
    
    (4)¯Á¤Þ§Ö³t.´y(indexfastfullscan)
    .´y¯Á¤Þ¤¤ªº©Ò¦³ªº.Õu.¡AÉOindexfullscan«Ü.¦ü¡A¦ý¬O¤@..µÛªº..´N
    ¬O¥¦¤£.¬d.¥Xªº.Õu.¦æ±Æ§Ç¡A§Y.Õu¤£¬O¥H±Æ§Ç.§Ç³Qªð¦^¡C¦b.Ïú¦s¨ú¤èªk¤¤¡A
    ¥i¥H¨Ï¥Î¦h..¥\¯à¡A¤]¥i¥H¨Ï¥Î¦}¦æ.¤J¡A¥H«K.±o³Ì¤j§]¦R¶qÉO.µu.¦æ..¡C
    
    ¯Á¤Þ§Ö³t.´yªº¨Ò¤l¡G
    BE_IX¯Á¤Þ¬O¤@.¦h¦C¯Á¤Þ¡Gbig_emp(empno,ename)
    
    SQL>explainplanforselectempno,enamefrombig_emp;
    QueryPlan
    ------------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    INDEXFASTFULLSCANBE_IX[ANALYZED]
    
    ¥u..¦h¦C¯Á¤Þªº²Ä2¦C¡G
    SQL>explainplanforselectenamefrombig_emp;
    QueryPlan
    ------------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=1
    INDEXFASTFULLSCANBE_IX[ANALYZED]
    
    
    ªí¤§.ªº.±µ
    Join¬O¤@Ïú.....ªí.¦X¦b¤@°_ªº..¡A¤@¦¸¥u¯à.±µ2.ªí¡Aªí.±µ¤]¥i¥H³Q
    ..ªí..¡C¦b¦Z­±ªº.­z¤¤¡A§Ú...¨Ï¥Î¡¨rowsource¡¨.¥N´À¡¨ªí¡¨¡A¦].¨Ï¥Îrowsource
    §ó..¤@¨Ç¡A¦}¥B..ÉO.±µªº2.rowsource¤À...rowsource1©Mrowsource2¡C
    Join.µ{ªº¦U.¨B..±`¬O¦ê¦æ¾Þ§@¡A§Y¨Ï¬Û.ªºrowsource¥i¥H³Q¦}¦æ..¡A§Y¥i¥H¦}
    ¦æªº.¨ú°µjoin.±µªº..rowsourceªº.Õu¡A¦ý¬O¦b.ªí¤¤²Å¦X­­¨î.¥óªº.Õu.¤J¨ì
    .¦s§Î¦¨rowsource¦Z¡Ajoinªº¨ä¥¦¨B.¤@¯ë¬O¦ê¦æªº¡C¦³¦hÏú¤èªk¥i¥H.2.ªí.±µ°_
    .¡A.µM¨CÏú¤èªk³£¦³¦Û¤vªºÉ¬¯Ê.¡A¨CÏú.±µ.«¬¥u¦³¦b¯S©wªº.¥ó¤U¤~...¥X¨ä³Ì¤j
    É¬.¡C
    
    rowsource(ªí)¤§.ªº.±µ.§Ç.¤_¬d.ªº®Ä²v¦³«D±`¤jªº¼v.¡C³q.­º¥ý¦s¨ú¯S©w
    ªºªí¡A§Y..ªí§@...ªí¡A..¥i¥H¥ý.¥Î¬Y¨Ç­­¨î.¥ó¡A.¦Ó±o¨ì¤@..¤pªºrow
    source¡A¨Ï.±µªº®Ä²v.°ª¡A.¤]´N¬O§Ú.±`.ªº­n¥ý.¦æ­­¨î.¥óªº­ì¦]¡C¤@¯ë¬O¦b.ªí
    .¤J.¦s.¡A.¥Îwhere¤l¥y¤¤..ªíªº­­¨î.¥ó¡C
    ®ÚÕu2.rowsourceªº.±µ.¥óªº¤¤¾Þ§@²Åªº¤£¦P¡A¥i¥H..±µ¤À.µ¥­È.±µ(¦p
    WHEREA.COL3=B.COL4)¡B«Dµ¥­È.±µ(WHEREA.COL3>B.COL4)¡B¥~.±µ(WHERE
    A.COL3=B.COL4(+))¡C¤W­±ªº¦U..±µªº.±µ­ì²z³£°ò¥»¤@.¡A©Ò¥H.¤F..´Á.¡A¤U­±
    ¥Hµ¥­È.±µ.¨Ò.¦æ¤¶.¡C¦b¦Z­±ªº¤¶.¤¤¡A³£¤w¡G
    SELECTA.COL1,B.COL2
    FROMA,B
    WHEREA.COL3=B.COL4;
    .¨Ò.¦æ.©ú¡A°².Aªí.RowSoruce1¡A.¨ä..ªº.±µ¾Þ§@..¦C.COL3¡FB
    ªí.RowSoruce2¡A.¨ä..ªº.±µ¾Þ§@..¦C.COL4¡F
    
    .±µ.«¬¡G
    ¥Ø«e.¤î¡A...±µ¾Þ§@²Å¦p¦ó¡A¨å«¬ªº.±µ.«¬¦@¦³3Ïú¡G
    ±Æ§Ç--¦X¦}.±µ(SortMergeJoin(SMJ))
    ´O®M´`.(NestedLoops(NL))
    «¢§Æ.±µ(HashJoin)
    
    ±Æ§Ç--¦X¦}.±µ(SortMergeJoin,SMJ)
    .³¡.±µ.µ{¡G
    1)­º¥ý¥Í¦¨rowsource1»Ý­nªº.Õu¡AµM¦Z..¨Ç.Õu«ö·Ó.±µ¾Þ§@..¦C(¦pA.col3)
    .¦æ±Æ§Ç¡C
    2).¦Z¥Í¦¨rowsource2»Ý­nªº.Õu¡AµM¦Z..¨Ç.Õu«ö·ÓÉOsortsource1..ªº.
    ±µ¾Þ§@..¦C(¦pB.col4).¦æ±Æ§Ç¡C
    3)³Ì¦Z..¤w±Æ§Çªº¦æ³Q©ñ¦b¤@°_.¦æ¦X¦}¾Þ§@¡A§Y.2.rowsource«ö·Ó.±µ.
    ¥ó.±µ°_.
    ¤U­±¬O.±µ¨B.ªº.§Îªí¥Ü¡G
    MERGE
    /\
    SORTSORT
    ||
    RowSource1RowSource2
    
    ¦pªGrowsource¤w.¦b.±µ..¦C¤W³Q±Æ§Ç¡A...±µ¾Þ§@´N¤£»Ý­n¦A.¦æsort
    ¾Þ§@¡A..¥i¥H¤j¤j´£°ª.Ïú.±µ¾Þ§@ªº.±µ³t«×¡A¦].±Æ§Ç¬O.Ìå¨ä..·½ªº¾Þ§@¡A
    ¯S.¬O.¤_.¤jªºªí¡C.¥ý±Æ§Çªºrowsource¥]¬A¤w.³Q¯Á¤Þªº¦C(¦pa.col3©Î
    b.col4¤W¦³¯Á¤Þ)©Îrowsource¤w.¦b«e­±ªº¨B.¤¤³Q±Æ§Ç¤F¡C.ºÞ¦X¦}..row
    sourceªº.µ{¬O¦ê¦æªº¡A¦ý¬O¥i¥H¦}¦æ.....rowsource(¦p¦}¦æ.¤J.Õu¡A¦}
    ¦æ±Æ§Ç).
    
    SMJ.±µªº¨Ò¤l¡G
    SQL>explainplanfor
    select/*+ordered*/e.deptno,d.deptno
    fromempe,deptd
    wheree.deptno=d.deptno
    orderbye.deptno,d.deptno;
    
    QueryPlan
    -------------------------------------
    SELECTSTATEMENT[CHOOSE]Cost=17
    MERGEJOIN
    SORTJOIN
    TABLEACCESSFULLEMP[ANALYZED]
    SORTJOIN
    TABLEACCESSFULLDEPT[ANALYZED]
    
    ±Æ§Ç¬O¤@...¡B..·½ªº¾Þ§@¡A¯S..¤_¤jªí¡C°ò¤_..­ì¦]¡ASMJ.±`¤£¬O
    ¤@.¯S.¦³®Äªº.±µ¤èªk¡A¦ý¬O¦pªG2.rowsource³£¤w..¥ý±Æ§Ç¡A..Ïú.±µ¤è
    ªkªº®Ä²v¤]¬O.°ªªº¡C
    
    ´O®M´`.(NestedLoops,NL)
    ...±µ¤èªk¦³..ªí(¥~³¡ªí)ªº·§©À¡C¨ä.¡A..±µ.µ{´N¬O¤@.2.´O®M´`
    .¡A©Ò¥H¥~.´`.ªº¦¸.¶V¤Ö¶V¦n¡A.¤]´N¬O§Ú..¤°¤\.¤pªí©Îªð¦^.¤prowsource
    ªºªí§@...ªí(¥Î¤_¥~.´`.)ªº²z.¨ÌÕu¡C¦ý¬O..²z.¥u¬O¤@¯ë«ü.­ì.¡A¦].
    ¿í´`..²z.¦}¤£¯à.«O.¨Ï.¥y.¥ÍªºI/O¦¸.³Ì¤Ö¡C¦³.¤£¿í¦u..²z.¨ÌÕu¡A
    ¤Ï¦Ó..±o§ó¦nªº®Ä²v¡C¦pªG¨Ï¥Î.Ïú¤èªk¡A.©w¨Ï¥Î­þ.ªí§@...ªí«Ü­«­n¡C¦³
    .¦pªG..ªí..¤£¥¿ÚÌ¡A...­P.¥yªº©Ê¯à«Ü®t¡B«Ü®t¡C
    
    .³¡.±µ.µ{¡G
    Rowsource1ªºRow1----------------Probe->Rowsource2
    Rowsource1ªºRow2----------------Probe->Rowsource2
    Rowsource1ªºRow3----------------Probe->Rowsource2
    ¡K¡K.
    Rowsource1ªºRown----------------Probe->Rowsource2
    ..³¡.±µ.µ{.¬Ý¡A»Ý­n¥Îrowsource1¤¤ªº¨C¤@¦æ¡A¥h¤Ç°trowsource2¤¤
    ªº©Ò¦³¦æ¡A©Ò¥H¦¹.«O«ùrowsource1.¥i¯àªº¤pÉO°ª®Äªº..rowsource2(¤@¯ë³q
    .¯Á¤Þ..)¬O¼v....±µ®Ä²vªº....¡C.¥u¬O²z.«ü.­ì.¡A¥Øªº¬O¨Ï¾ã..
    ±µ¾Þ§@.¥Í³Ì¤Öªºª«²zI/O¦¸.¡A¦Ó¥B¦pªG¿í¦u..­ì.¡A¤@¯ë¤].¨Ï.ªºª«²zI/O
    .³Ì¤Ö¡C¦ý¬O¦pªG¤£¿í...«ü.­ì.¡A¤Ï¦Ó¯à¥Î§ó¤Öªºª«²zI/O...±µ¾Þ§@¡A¨º
    .ºÞ.¤Ï«ü.­ì.§a¡I¦].³Ì¤Öªºª«²zI/O¦¸.¤~¬O§Ú...¿í.ªº¯u¥¿ªº«ü.­ì.¡A
    ¦b¦Z­±ªº¨ãÊ^®×¨Ò¤ÀªR¤¤´N.¥X..ªº¨Ò¤l¡C
    
    ¦b¤W­±ªº.±µ.µ{¤¤¡A§Ú..Rowsource1...ªí©Î¥~³¡ªí¡CRowSource2³Q
    ..³Q±´¬dªí©Î.³¡ªí¡C
    
    ¦bNESTEDLOOPS.±µ¤¤¡AOracle.¨úrowsource1¤¤ªº¨C¤@¦æ¡AµM¦Z¦brow
    sourc2¤¤.¬d¬O§_¦³¤Ç°tªº¦æ¡A©Ò¦³³Q¤Ç°tªº¦æ³£³Q©ñ¨ì.ªG¶°¤¤¡AµM¦Z.²zrow
    source1¤¤ªº¤U¤@¦æ¡C...µ{¤@ª½..¡Aª½¨ìrowsource1¤¤ªº©Ò¦³¦æ³£³Q.²z¡C
    .¬O..±µ¾Þ§@¤¤¥i¥H±o¨ì²Ä¤@.¤Ç°t¦æªº³Ì§Öªº¤èªk¤§¤@¡A.Ïú.«¬ªº.±µ¥i¥H¥Î
    ¦b»Ý­n§Ö³t..ªº.¥y¤¤¡A¥H..³t«×.¥D­n¥Ø.¡C
    
    ¦pªGdrivingrowsource(¥~³¡ªí)¤ñ.¤p¡A¦}¥B¦binnerrowsource(.³¡ªí)¤W¦³°ß
    ¤@¯Á¤Þ¡A©Î¦³°ª..©Ê«D°ß¤@¯Á¤Þ.¡A¨Ï¥Î.Ïú¤èªk¥i¥H±o¨ì.¦nªº®Ä²v¡CNESTED
    LOOPS¦³¨ä¥¦.±µ¤èªk.¦³ªºªº¤@.ɬ.¬O¡G¥i¥H¥ýªð¦^¤w..±µªº¦æ¡A¦Ó¤£¥²µ¥
    «Ý©Ò¦³ªº.±µ¾Þ§@.²z§¹¤~ªð¦^.Õu¡A.¥i¥H..§Ö³tªº....¡C
    
    ¦pªG¤£¨Ï¥Î¦}¦æ¾Þ§@¡A³Ì¦nªº..ªí¬O¨º¨Ç.¥Î¤Fwhere­­¨î.¥ó¦Z¡A¥i¥Hªð¦^
    .¤Ö¦æ.Õuªºªºªí¡A©Ò¥H¤jªí¤]¥i¯à....ªí¡A..¬Ý­­¨î.¥ó¡C.¤_¦}¦æ¬d.¡A
    §Ú..±`..¤jªí§@...ªí¡A¦].¤jªí¥i¥H¥R¤À§Q¥Î¦}¦æ¥\¯à¡C.µM¡A¦³..¬d.
    ¨Ï¥Î¦}¦æ¾Þ§@¦}¤£¤@©w.¤ñ¬d.¤£¨Ï¥Î¦}¦æ¾Þ§@®Ä²v°ª¡A¦].³Ì¦Z¥i¯à¨C.ªí¥u¦³«Ü
    ¤Öªº¦æ²Å¦X­­¨î.¥ó¡A¦Ó¥B.­n¬Ý§Aªºµw¥ó°t¸m¬O§_¥i¥H¤ä«ù¦}¦æ(¦p¬O§_¦³¦h.
    CPU¡A¦h.µw.±±¨î¾¹)¡A©Ò¥H­n¨ãÊ^..¨ãÊ^.«Ý¡C
    
    NL.±µªº¨Ò¤l¡G
    SQL>explainplanfor
    selecta.dname,b.sql
    fromdepta,empb
    wherea.deptno=b.deptno;
    
    QueryPlan
    -------------------------
    SELECTSTATEMENT[CHOOSE]Cost=5
    NESTEDLOOPS
    TABLEACCESSFULLDEPT[ANALYZED]
    TABLEACCESSFULLEMP[ANALYZED]
    
    «¢§Æ.±µ(HashJoin,HJ)
    .Ïú.±µ¬O¦boracle7.3¥H¦Z¤Þ¤Jªº¡A.²z.¤W..¤ñNLÉOSMJ§ó°ª®Ä¡A¦Ó¥B
    ¥u¥Î¦bCBOɬ¤Æ¾¹¤¤¡C
    .¤pªºrowsource³Q¥Î.ÌÛ«ØhashtableÉObitmap¡A²Ä2.rowsource³Q¥Î.
    ³Qhansed¡A¦}ÉO²Ä¤@.rowsource¥Í¦¨ªºhashtable.¦æ¤Ç°t¡A¥H«K.¦æ.¤@¨Bªº
    .±µ¡CBitmap³Q¥Î.§@.¤@Ïú¤ñ.§Öªº¬d§ä¤èªk¡A..¬d¦bhashtable¤¤¬O§_¦³¤Ç°t
    ªº¦æ¡C¯S.ªº¡A.hashtable¤ñ.¤j¦Ó¤£¯à¥þ³¡®e.¦b.¦s¤¤.¡A.Ïú¬d§ä¤èªk§ó.
    ¦³¥Î¡C.Ïú.±µ¤èªk¤]¦³NL.±µ¤¤©Ò.ªº..ªíªº·§©À¡A³QÌÛ«Ø.hashtableÉO
    bitmapªºªí...ªí¡A.³QÌ۫تºhashtableÉObitmap¯à³Q®e.¦b.¦s¤¤.¡A.Ïú
    .±µ¤è¦¡ªº®Ä²vÌå°ª¡C
    
    HASH.±µªº¨Ò¤l¡G
    SQL>explainplanfor
    select/*+use_hash(emp)*/empno
    fromemp,dept
    whereemp.deptno=dept.deptno;
    
    QueryPlan
    ----------------------------
    SELECTSTATEMENT[CHOOSE]Cost=3
    HASHJOIN
    TABLEACCESSFULLDEPT
    TABLEACCESSFULLEMP
    
    ­n¨Ï«¢§Æ.±µ¦³®Ä¡A»Ý­n.¸mHASH_JOIN_ENABLED=TRUE¡A¯Ê¬Ù±¡.¤U..
    ..TRUE¡A¥t¥~¡A¤£­n§Ñ¤F.­n.¸mhash_area_size..¡A¥H¨Ï«¢§Æ.±µ°ª®Ä.
    ¦æ¡A¦].«¢§Æ.±µ.¦b...«ü©w¤j¤pªº.¦s¤¤.¦æ¡A.¤pªº...¨Ï«¢§Æ.±µªº©Ê
    ¯à¤ñ¨ä¥L.±µ¤è¦¡.­n§C¡C
    
    ..¤@¤U¡A¦b­þÏú±¡.¤U¥Î­þÏú.±µ¤èªk¤ñ.¦n¡G
    ±Æ§Ç--¦X¦}.±µ(SortMergeJoin,SMJ)¡G
    a).¤_«Dµ¥­È.±µ¡A.Ïú.±µ¤è¦¡ªº®Ä²v¬O¤ñ.°ªªº¡C
    b)¦pªG¦b..ªº¦C¤W³£¦³¯Á¤Þ¡A®ÄªG§ó¦n¡C
    c).¤_.2..¤jªºrowsource°µ.±µ¡A..±µ¤èªk¤ñNL.±µ­n¦n¤@¨Ç¡C
    d)¦ý¬O¦pªGsortmergeªð¦^ªºrowsource.¤j¡A.¤S..­P¨Ï¥Î.¦hªºrowid
    ¦bªí¤¤¬d..Õu.¡A.Õu.©Ê¯à¤U­°¡A¦]..¦hªºI/O¡C
    ´O®M´`.(NestedLoops,NL)¡G
    a)¦pªGdrivingrowsource(¥~³¡ªí)¤ñ.¤p¡A¦}¥B¦binnerrowsource(.³¡ªí)¤W
    ¦³°ß¤@¯Á¤Þ¡A©Î¦³°ª..©Ê«D°ß¤@¯Á¤Þ.¡A¨Ï¥Î.Ïú¤èªk¥i¥H±o¨ì.¦nªº®Ä²v¡C
    b)NESTEDLOOPS¦³¨ä¥¦.±µ¤èªk.¦³ªºªº¤@.ɬ.¬O¡G¥i¥H¥ýªð¦^¤w.
    .±µªº¦æ¡A¦Ó¤£¥²µ¥«Ý©Ò¦³ªº.±µ¾Þ§@.²z§¹¤~ªð¦^.Õu¡A
    .¥i¥H..§Ö³tªº....¡C
    «¢§Æ.±µ(HashJoin,HJ)¡G
    a).Ïú¤èªk¬O¦boracle7¦Z.¤Þ¤Jªº¡A¨Ï¥Î¤F¤ñ.¥ý.ªº.±µ²z.¡A
    ¤@¯ë..¡A¨ä®Ä²v..¦n¤_¨ä¥¦2Ïú.±µ¡A¦ý¬O.Ïú.±µ¥u¯à¥Î¦b
    CBOɬ¤Æ¾¹¤¤¡A¦Ó¥B»Ý­n.¸m¦XÓ쪺hash_area_size..¡A
    ¤~¯à¨ú±o.¦nªº©Ê¯à¡C
    b)¦b2..¤jªºrowsource¤§..±µ..¨ú±o¬Û..¦nªº®Ä²v¡A¦b¤@.
    rowsource.¤p..¯à¨ú±o§ó¦nªº®Ä²v¡C
    c)¥u¯à¥Î¤_µ¥­È.±µ¤¤
    
    ²Ã¥d¤I­¼.(CartesianProduct)
    ...rowsource°µ.±µ¡A¦ý¬O¥¦.¤§..¦³...¥ó.¡A´N.¦b..rowsource
    ¤¤°µ²Ã¥d¤I­¼.¡A.³q±`¥Ñ..¥N.²¨º|³y¦¨(§Yµ{§Ç.§Ñ¤F....¥ó)¡C²Ã¥d.­¼
    .¬O¤@.ªíªº¨C¤@¦æ¨Ì¦¸ÉO¥t¤@.ªí¤¤ªº©Ò¦³¦æ¤Ç°t¡C¦b¯S®í±¡.¤U§Ú.¥i¥H¨Ï¥Î²Ã
    ¥d¤I­¼.¡A¦p¦b¬P§Î.±µ¤¤¡A°£¦¹¤§¥~¡A§Ú.­n.¶q¨Ï¥Î²Ã¥d¤I­¼.¡A§_.¡A¦Û¤v·Q
    .ªG¬O¤°¤\§a¡I
    
    ª`·N¦b¤U­±ªº.¥y¤¤¡A¦b2.ªí¤§..¦³.±µ¡C
    SQL>explainplanfor
    selectemp.deptno,dept,deptno
    fromemp,dept
    
    QueryPlan
    ------------------------------
    SLECTSTATEMENT[CHOOSE]Cost=5
    MERGEJOINCARTESIAN
    TABLEACCESSFULLDEPT
    SORTJOIN
    TABLEACCESSFULLEMP
    
    CARTESIAN..¦r«ü¥X¤F¦b2.ªí¤§.°µ²Ã¥d.­¼.¡C°²¦pªíemp¦³n¦æ¡Adept
    ªí¦³m¦æ¡A²Ã¥d.­¼.ªº.ªG´N¬O±o¨ìn*m¦æ.ªG¡C
    
    
    
    ¦p¦ó.¥Í.¦æ.¦E
    ­n.¤@..¥y¥Í¦¨.¦æ.¦E¡A¥i¥H¦³3Ïú¤èªk¡G
    1)¡D³Ì..ªº.ªk
    Sql>setautotraceon
    Sql>select*fromdual;
    .¦æ§¹.¥y¦Z¡A..¥ÜexplainplanÉO..«H®§¡C
    ...¥yªºÉ¬.´N¬O¥¦ªº¯Ê.¡A..¦b¥Î.¤èªk¬d¬Ý.¦æ....ªºsql.¥y.¡A»Ý­nµ¥«Ý
    ..¥y.¦æ¦¨¥\¦Z¡A¤~ªð¦^.¦æ.¦E¡A¨Ïɬ¤Æªº©P´Á¤j¤j¼W.¡C
    
    ¦pªG¤£·Q.¦æ.¥y¦Ó¥u¬O·Q±o¨ì.¦æ.¦E¥i¥Hªö¥Î¡G
    Sql>setautotracetraceonly
    ..¡A´N¥u.¦C¥X.¦æ.¦E¡A¦Ó¤£.¯u¥¿ªº.¦æ.¥y¡A¤j¤j.¤Ö¤Fɬ¤Æ..¡C.µM¤]¦C¥X¤F
    ..«H®§¡A¦ý¬O¦]..¦³.¦æ.¥y¡A©Ò¥H...«H®§.¦³¥Î.¡A
    
    
    ¦pªG.¦æ..¥y.¹J¨ì..¡A¸Ñ.¤èªk.¡G
    (1¡^¦b­n¤ÀªRªº¥Î.¤U¡G
    Sqlplus>@?\rdbms\admin\utlxplan.sql
    (2)¥Îsys¥Î.µn.
    Sqlplus>@?\sqlplus\admin\plustrce.sql
    Sqlplus>grantplustracetouser_name;--user_name¬O¤W­±©Ò.ªº¤ÀªR¥Î.
    
    2)¡D¥Îexplainplan©R¥O
    (1)sqlplus>@?\rdbms\admin\utlxplan.sql
    (2)sqlplus>explainplansetstatement_id=¡¦???¡¦forselect¡K¡K¡K¡K¡K¡K
    ª`·N¡A¥Î¦¹¤èªk.¡A¦}¤£.¦æsql.¥y¡A©Ò¥H¥u.¦C¥X.¦æ.¦E¡A¤£.¦C¥X..«H®§¡A¦}¥B
    .¦æ.¦E¥u¦s¦bplan_table¤¤¡C©Ò¥H..¥y¤ñ°_setautotracetraceonly¥i¥Î©Ê­n®t¡C»Ý­n
    ¥Î¤U­±ªº©R¥O®æ¦¡¤Æ.¥X¡A©Ò¥H.Ïú¤è¦¡§Ú¥Îªº¤£¦h¡G
    
    setlinesize150
    setpagesize500
    colPLANLINEfora120
    SELECTEXECORDEXEC_ORDER,PLANLINE
    FROM(SELECTPLANLINE,ROWNUMEXECORD,ID,RID
    FROM(SELECTPLANLINE,ID,RID,LEV
    FROM(SELECTlpad('',2*(LEVEL),rpad('',80,''))||
    OPERATION||''||--Operation
    DECODE(OPTIONS,NULL,'','('||OPTIONS||')')||--Options
    DECODE(OBJECT_OWNER,null,'','OF'''||OBJECT_OWNER||'.')||--
    Owner
    DECODE(OBJECT_NAME,null,'',OBJECT_NAME||'''')||--ObjectName
    DECODE(OBJECT_TYPE,null,'','('||OBJECT_TYPE||')')||--Object
    Type
    DECODE(ID,0,'OPT_MODE:')||--Optimizer
    DECODE(OPTIMIZER,null,'','ANALYZED','',OPTIMIZER)||
    DECODE(NVL(COST,0)+NVL(CARDINALITY,0)+NVL(BYTES,0),
    0,null,'(COST='||TO_CHAR(COST)||',CARD='||
    TO_CHAR(CARDINALITY)||',BYTES='||TO_CHAR(BYTES)||')')
    PLANLINE,ID,LEVELLEV,
    (SELECTMAX(ID)
    FROMPLAN_TABLEPL2
    CONNECTBYPRIORID=PARENT_ID
    ANDPRIORSTATEMENT_ID=STATEMENT_ID
    STARTWITHID=PL1.ID
    ANDSTATEMENT_ID=PL1.STATEMENT_ID)RID
    FROMPLAN_TABLEPL1
    CONNECTBYPRIORID=PARENT_ID
    ANDPRIORSTATEMENT_ID=STATEMENT_ID
    STARTWITHID=0
    ANDSTATEMENT_ID='aaa')
    ORDERBYRID,-LEV))
    ORDERBYID;
    
    ¤W­±.2Ïú¤èªk¥u¯à.¦b¥»..¤¤¥¿¦b.¦æªº.¥y.¥Í.¦æ.¦E¡A§Y§Ú.»Ý­n¤w.ª¾¹D¤F
    ­þ..¥y.¦æªº®Ä²v«Ü®t¡A§Ú.¬O¦³¥Øªº¥u...SQL.¥y¥hɬ¤Æ¡C¨ä.¡A¦b«Ü¦h±¡.¤U¡A
    §Ú.¥u.§v¤@.«È.©ê«è..¦b¨t..¦æ«ÜºC¡A¦Ó§Ú.¤£ª¾¹D¬O­þ.SQL¤Þ°_ªº¡C¦¹.¦³
    .¦h.¦¨ªº.¥y¥i¥H§ä¥X¯Ó..·½¤ñ.¦hªº.¥y¡A¦p¡G
    SELECTADDRESS,
    substr(SQL_TEXT,1,20)Text,
    buffer_gets,
    executions,
    buffer_gets/executionsAVG
    FROMv$sqlarea
    WHEREexecutions>0
    ANDbuffer_gets>100000
    ORDERBY5;
    .¦Ó.§ä¥Xªº.¥y.¦æ.¤@¨Bɬ¤Æ¡C.µM§Ú..¥i¥H.¤@.¥¿¦b.¦æªº..¤¤.¦æªº
    ©Ò¦³SQL.¥y¥Í¦¨.¦æ.¦E¡A.»Ý­n.....¦æ¸ò.¡A.¥Ítrace¤å¥ó¡AµM¦Z..¤å¥ó
    ¥Îtkprofµ{§Ç®æ¦¡¤Æ¤@¤U¡A.Ïú±o¨ì.¦æ.¦Eªº¤è¦¡«Ü¦³¥Î¡A¦].¥¦¥]§t¨ä¥¦.¥~«H®§¡A¦p
    SQL.¥y.¦æªº¨C..¬q(¦pParse¡BExecute¡BFetch)¤À.¯Ó.ªº¦U..·½±¡.(¦pCPU¡B
    DISK¡Belapsedµ¥)¡C
    
    3)¡D¥Îdbms_system¦s..µ{¥Í¦¨.¦æ.¦E
    ¦].¨Ï¥Îdbms_system¦s..µ{¥i¥H¸ò.¥t¤@....¥Xªºsql.¥y¡A¦}..©Ò¨Ï¥Î
    ªº.¦æ.¦E¡A¦Ó¥B.´£¨Ñ¨ä¥¦.©Ê¯à.¾ã¦³¥Îªº«H®§¡C¦]¨ä¨Ï¥Î¤è¦¡ÉO¤W­±2Ïú¤è¦¡¦³¨Ç
    ¤£¤Ó¤@.¡A©Ò¥H¦bªþ.¤¤..¤¶.¡C.Ïú¤èªk¬O.SQL.¦æ.¾ã¤ñ.¦³¥Îªº¤è¦¡¤§¤@¡A¦³
    ¨Ç±¡.¤U«D¥¦¤£¥i¡C¨ãÊ^.®e..ªþ.¡C
    
    ¦p¦ó¤ÀªR.¦æ.¦E
    
    ¨Ò1¡G
    °².LARGE_TABLE¬O¤@..¤jªºªí¡A¥Busername¦C¤W.¦³¯Á¤Þ¡A..¦æ¤U­±ªº.¥y¡G
    SQL>SELECT*FROMLARGE_TABLEwhereUSERNAME=¡¥TEST¡¦;
    QueryPlan
    -----------------------------------------
    SELECTSTATEMENTOptimizer=CHOOSE(Cost=1234Card=1Bytes=14)
    TABLEACCESSFULLLARGE_TABLE[:Q65001][ANALYZED]
    
    ¦b..¨Ò¤l¤¤¡ATABLEACCESSFULLLARGE_TABLE¬O²Ä¤@.¾Þ§@¡A·N«ä¬O¦b
    LARGE_TABLEªí¤W°µ¥þªí.´y¡C...¾Þ§@§¹¦¨¤§¦Z¡A.¥Íªºrowsource¤¤ªº.Õu³Q°e
    ©¹¤U¤@¨B..¦æ.²z¡A¦b¦¹¨Ò¤¤¡ASELECTSTATEMENT¾Þ§@¬O..¬d..¥yªº³Ì¦Z¤@¨B¡C
    
    Optimizer=CHOOSE«ü©ú..¬d.ªºoptimizer_mode¡A§Yoptimizer_modeªì©l¤Æ..«ü
    ©wªº­È¡A¥¦¦}¤£¬O«ü.¥y.¦æ.¯uªº¨Ï¥Î¤F.ɬ¤Æ¾¹¡C.©w..¥y¨Ï¥Î¦óÏúɬ¤Æ¾¹ªº°ß¤@¤è
    ªk¬O¬Ý¦Z­±ªºcost³¡¤À¡C¨Ò¦p¡A¦pªG.¥Xªº¬O¤U­±ªº§Î¦¡¡A.ªí©ú¨Ï¥Îªº¬OCBOɬ¤Æ¾¹¡A
    ¦¹.ªºcostªí¥Üɬ¤Æ¾¹....¦æ.¦Eªº¥Nɲ:
    SELECTSTATEMENTOptimizer=CHOOSE(Cost=1234Card=1Bytes=14)
    
    µM¦Ó°²¦p.¦æ.¦E¤¤.¥Xªº¬O.¦ü¤U­±ªº«H®§¡A.ªí©ú¬O¨Ï¥ÎRBOɬ¤Æ¾¹¡A¦].cost
    ³¡¤Àªº­È.ªÅ¡A©ÎªÌ.®Ú´N.¦³cost³¡¤À¡C
    SELECTSTATEMENTOptimizer=CHOOSECost=
    SELECTSTATEMENTOptimizer=CHOOSE
    ..§Ú..Optimizer¦Z­±ªº«H®§¤¤¥i¥H±o¥X.¦æ..¥y.¨ì©³¥Î¤F¤°¤\.ªºÉ¬¤Æ
    ¾¹¡C¯S.ªº¡A¦pªGOptimizer=ALL_ROWS|FIRST_ROWS|FIRST_ROWS_n¡A.¨Ï¥Îªº¬O
    CBOɬ¤Æ¾¹¡F¦pªGOptimizer=RULE¡A.¨Ï¥Îªº¬ORBOɬ¤Æ¾¹¡C
    
    cost.©Êªº­È¬O¤@.¦boracle.³¡¥Î.¤ñ.¦U..¦æ.¦E©Ò¯Ó.ªº¥Nɲªº­È¡A.¦Ó¨Ï
    É¬¤Æ¾¹¥i¥H..³Ì¦nªº.¦æ.¦E¡C¤£¦P.¥yªºcost­È¤£¨ã¦³¥i¤ñ©Ê¡A¥u¯à.¦P¤@..¥yªº
    ¤£¦P.¦æ.¦Eªºcost­È.¦æ¤ñ.¡C
    
    [:Q65001]ªí©ú.³¡¤À¬d.¬O¥H¦}¦æ¤è¦¡.¦æªº¡C¨½­±ªº.Õuªí¥Ü..¾Þ§@¬O¥Ñ¦}¦æ¬d.ªº
    ¤@.slave.µ{.²zªº¡A¥H«K.¾Þ§@¥i¥H..¤_¦ê¦æ.¦æªº¾Þ§@¡C
    
    [ANALYZED]ªí©ú¾Þ§@¤¤¤Þ¥Îªº.¶H³Q¤ÀªR.¤F¡A¦b.Õu¦r¨å¤¤¦³..¶Hªº..«H®§¥i¥H
    ¨ÑCBO¨Ï¥Î¡C
    
    ¨Ò2¡G
    °²©wA¡BB¡BC³£¬O¤£¬O¤pªí¡A¥B¦bAªí¤W¤@..¦X¯Á¤Þ¡GA(a.col1,a.col2)¡Aª`·Na.col1
    ¦C.¯Á¤Þªº¤Þ.¦C¡C
    ¦Ò.¤U­±ªº¬d.¡G
    selectA.col4
    fromA,B,C
    whereB.col3=10andA.col1=B.col1andA.col2=C.col2andC.col3=5
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE
    10MERGEJOIN
    21SORT(JOIN)
    32NESTEDLOOPS
    43TABLEACCESS(FULL)OF'B'
    53TABLEACCESS(BYINDEXROWID)OF'A'
    65INDEX(RANGESCAN)OF'INX_COL12A'(NON-UNIQUE)
    71SORT(JOIN)
    87TABLEACCESS(FULL)OF'C'
    
    Statistics
    ----------------------------------------------------------
    0recursivecalls
    8dbblockgets
    6consistentgets
    0physicalreads
    0redosize
    551bytessentviaSQL*Nettoclient
    430bytesreceivedviaSQL*Netfromclient
    2SQL*Netroundtripsto/fromclient
    2sorts(memory)
    0sorts(disk)
    6rowsprocessed
    
    ¦bªí°µ.±µ.¡A¥u¯à2.ªí¥ý°µ.±µ¡AµM¦Z..±µ¦Zªº.ªG§@.¤@.rowsource¡AÉO
    ³Ñ¤Uªºªí°µ.±µ¡A¦b¤W­±ªº¨Ò¤l¤¤¡A.±µ.§Ç.BÉOA¥ý.±µ¡AµM¦Z¦AÉOC.±µ¡G
    B<--->A<--->C
    col3=10col3=5
    
    ¦pªG.¦³.¦æ.¦E¡A¤ÀªR¤@¤U¡A¤W­±ªº3.ªí..®³­þ¤@.§@.²Ä¤@...ªí¡H.SQL
    .¥y¬Ý.¡A¥u¦³BªíÉOCªí¤W¦³­­¨î.¥ó¡A©Ò¥H²Ä¤@...ªí....2.ªí¤¤ªº¤@.¡A
    ¨ì©³¬O­þ¤@.©O¡H
    
    Bªí¦³..B.col3=10¡A..¦b.Bªí°µ¥þªí.´yªº.­Ô´N.where¤l¥y¤¤ªº­­¨î
    .¥ó(B.col3=10)¥Î¤W¡A.¦Ó±o¨ì¤@..¤pªºrowsource,©Ò¥HBªí..§@.²Ä¤@...ªí¡C
    ¦Ó¥B..ªº.¡A¦pªG¦AÉOAªí°µ..¡A¥i¥H¦³®Ä§Q¥ÎAªíªº¯Á¤Þ(¦].Aªíªºcol1¦C.leading
    column)¡C
    
    .µM¤W­±ªº¬d.¤¤Cªí¤W¤]¦³..(C.col3=5)¡A¦³¤H¥i¯à..Cªí§@.²Ä¤@...
    ªí¤]¯à.±o.¦nªº©Ê¯à¡C.§Ú.¦A.¤ÀªR¤@¤U¡G¦pªGCªí§@.²Ä¤@...ªí¡A.¯à«O..
    .ªí¥Í¦¨«Ü¤pªºrowsource¡A¦ý¬O¬Ý¬Ý.±µ.¥óA.col2=C.col2¡A¦¹.´N.¦³Éó.§Q¥ÎA
    ªíªº¯Á¤Þ¡A¦].Aªíªºcol2¦C¤£.leadingcolumn¡A..nestedloopªº®Ä²v«Ü®t¡A.¦Ó
    .­P¬d.ªº®Ä²v«Ü®t¡C©Ò¥H.¤_NL.±µ..¥¿Ú̪º..ªí«Ü­«­n¡C
    
    ¦]¦¹¤W­±¬d.¤ñ.¦nªº.±µ.§Ç.(B-->A)-->C¡C¦pªG.Õu.¬O°ò¤_¥NɲªºÉ¬¤Æ
    ¾¹¡A¥¦.§Q¥Î.ºâ¥Xªº¥Nɲ..©w¦XÓ쪺..ªíÉO¦XÓ쪺.±µ.§Ç¡C¤@¯ë..¡ACBO³£.
    ..¥¿Ú̪º.±µ.§Ç¡A¦pªGCBO..¤F¤ñ.®tªº.±µ.§Ç¡A§Ú..¥i¥H¨Ï¥ÎORACLE´£
    ¨Ñªºhints..CBOªö¥Î¥¿Ú̪º.±µ.§Ç¡C¦p¤U©Ò¥Ü¡G
    
    select/*+ordered*/A.col4
    fromB,A,C
    whereB.col3=10
    andA.col1=B.col1
    andA.col2=C.col2
    andC.col3=5
    
    ¬JµM..¥¿Ú̪º..ªí.¤\­«­n¡A¨º¤\.§Ú..¬Ý¤@¤U.¦æ.¦E¡A¨ì©³¦U.ªí¤§.¬O
    ¦p¦ó..ªº¡A.¦Ó±o¨ì.¦æ.¦E¤¤­þ.ªí.....ªí¡G
    ¦b.¦æ.¦E¤¤¡A»Ý­nª¾¹D­þ.¾Þ§@¬O¥ý.¦æªº¡A­þ.¾Þ§@¬O¦Z.¦æªº¡A..¤_§P.­þ
    .ªí...ªí¦³¥Î.¡C§P.¤§«e¡A¦pªG.ªíªº..¬O³q.rowid¡A¥B.rowidªº­È¬O.¯Á¤Þ
    .´y¤¤±o.±o¡A...¯Á¤Þ.´y¥ý..¦æ.¦E¤¤..¥h±¼¡CµM¦Z¦b.¦æ.¦E³Ñ¤Uªº³¡¤À¤¤¡A
    §P..¦æ.§Çªº«ü.­ì.´N¬O¡G³Ì¥k¡B³Ì¤Wªº¾Þ§@¥ý.¦æ¡C¨ãÊ^¸Ñ.¦p¤U¡G
    ±o¨ì¥h°£§«.§P.ªº¯Á¤Þ.´y¦Zªº.¦æ.¦E¡G
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE
    10MERGEJOIN
    21SORT(JOIN)
    32NESTEDLOOPS
    43TABLEACCESS(FULL)OF'B'
    53TABLEACCESS(BYINDEXROWID)OF'A'
    71SORT(JOIN)
    87TABLEACCESS(FULL)OF'C'
    ¬Ý.¦æ.¦Eªº²Ä3¦C¡A§Y¦r¥À³¡¤À¡A¨C¦C­Èªº¥ª­±¦³ªÅ®æ§@...¦r²Å¡C¦b.¦C­È¥ª
    .ªºªÅ®æ¶V¦h¡A.©ú.¦C­Èªº..¶V¦h¡A.¦C­È¤]¶V¾a¥k¡C¦p¤W­±ªº.¦æ.¦E©Ò¥Ü¡G²Ä¤@¦C
    ­È.6ªº¦æªº..³Ì¦h¡A§Y.¦æ³Ì¾a¥k¡F²Ä¤@¦C­È.4¡B5ªº¦æªº..¤@.¡A¨ä¾a¥kªºµ{«×
    ¤]¤@.¡A¦ý¬O²Ä¤@¦C­È.4ªº¦æ¤ñ²Ä¤@¦C­È.5ªº¦æ¾a¤W¡F..¤W¤U.¨t.¡A¥u...ªº¡B
    ..¤@­Pªº¦æ¦³®Ä¡C
    
    ....¤¤§Ú.¥i¥H¬Ý¨ì¡A.¤_NESTEDLOOPS³¡¤À¡A³Ì¥k¡B³Ì¤Wªº¾Þ§@¬OTABLE
    ACCESS(FULL)OF'B'¡A©Ò¥H.¤@¾Þ§@¥ý.¦æ¡A©Ò¥H.¾Þ§@..ªºBªí.²Ä¤@...ªí(¥~
    ³¡ªí)¡A¦ÛµM¡AAªí´N..³¡ªí¤F¡C..¤¤.¥i¥H¬Ý¥X¡ABÉOAªí°µ´O®M´`.¦Z¥Í¦¨¤F·sªº
    rowsource¡A..rowsource.¦æ.±Æ§Ç¦Z¡AÉOCªí..ªº±Æ§Ç¤Fªºrowsource(.¥Î¤F
    C.col3=5­­¨î.¥ó).¦æMSJ.±µ¾Þ§@¡C©Ò¥H.¤W­±¥i¥H±o¥X¦p¤U¨Æ.¡GBªí¥ýÉOAªí°µ
    ´O®M´`.¡AµM¦Z.¥Í¦¨ªºrowsourceÉOCªí°µ±Æ§Ç¡X¦X¦}.±µ¡C
    ³q.¤ÀªR¤W­±ªº.¦æ.¦E¡A§Ú.¤£¯à.Cªí¤@©w¦bB¡BAªí¤§¦Z¤~³Q.¨ú¡A¨Æ.¤W¡A
    Bªí¦³¥i¯àÉOCªí¦P.³Q.¤J.¦s¡A¦]..ªí¤¤ªº.Õu.¤J.¦sªº¾Þ§@¥i¯à.¦}¦æªº¡C¨Æ
    .¤W.¦h¾Þ§@¥i¯à.¥æ¤e.¦æªº¡A¦].ORACLE.¨ú.Õu.¡A¦pªG´N¬O»Ý­n¤@¦æ.Õu¤]¬O
    ..¦æ©Ò¦bªº¾ã..Õu..¤J.¦s¡A¦Ó¥B.¦³¥i¯à.¦h..¡C
    ¬Ý.¦æ.¦E.¡A§Ú.ªº..¤£¬O¬Ý­þ.¾Þ§@¥ý.¦æ¡A­þ.¾Þ§@¦Z.¦æ¡A¦Ó¬O..¬Ýªí
    ¤§..±µªº.§Ç(¦p±oª¾­þ....ªí¡A.»Ý­n.¾Þ§@ªº.§Ç.¦æ§P.)¡B¨Ï¥Î¤F¦óÏú.«¬ªº
    ..¤Î¨ãÊ^ªº¦s¨ú¸ô.(¦p§P.¬O§_§Q¥Î¤F¯Á¤Þ)
    
    ¦b..¦æ.¦E¤¤§P.¥X­þ.ªí...ªí¦Z¡A®ÚÕu§Ú.ªºª¾.§P..ªí§@...ªí(´N¹³
    ¤W­±§P.ABCªí¨º.)¬O§_¦XÓì¡A¦pªG¤£¦XÓì¡A.SQL.¥y.¦æ§ó§ï¡A¨Ïɬ¤Æ¾¹¥i¥H..
    ¥¿Ú̪º..ªí¡C
    
    .¤_RBOɬ¤Æ¾¹¡G
    ¦bORACLE¤å.¤W.¡G.¤_RBO..¡A¥Hfrom¤l¥y¤¤.¥k¨ì¥ªªº.§Ç....ªí¡A
    §Y³Ì¥k.ªºªí.²Ä¤@...ªí¡A.¬O¨ä­^¤å­ì¤å¡GAllthingsbeingequalRBOchoosesthe
    drivingorderbytakingthetablesintheFROMclauseRIGHTtoLEFT¡C¤£.¡A¦b§Ú°µªº.
    .¤¤¡A..¤].¦³....Ïú.ªk¬O¥¿Ú̪º¡C§Ú..¡A§Y¨Ï¦bRBO¤¤¡A¤]¬O¦³¤@®M...
    .©w¨Ï¥Î­þÏú.±µ.«¬©M­þ.ªí§@...ªí¡A¦b...ªÖ©w.¦Ò..«e¯Á¤Þªº±¡.¡A.¥i¯à
    .¦Ò.where¤¤ªº­­¨î.¥ó¡A¦ý¬OªÖ©w¬OÉOwhere¤¤­­¨î.¥óªº¦ì¸m..¡C
    
    ..¡G
    ¦pªG§Ú.«Ø3.ªí¡G
    createtableA(col1number(4,0),col2number(4,0),col4char(30));
    createtableB(col1number(4,0),col3number(4,0),name_bchar(30));
    createtableC(col2number(4,0),col3number(4,0),name_cchar(30));
    createindexinx_col12Aona(col1,col2);
    .¦æ¬d.¡G
    selectA.col4
    fromB,A,C
    whereB.col3=10
    andA.col1=B.col1
    andA.col2=C.col2
    andC.col3=5;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=RULE
    10MERGEJOIN
    21SORT(JOIN)
    32NESTEDLOOPS
    43TABLEACCESS(FULL)OF'B'
    53TABLEACCESS(BYINDEXROWID)OF'A'
    65INDEX(RANGESCAN)OF'INX_COL12A'(NON-UNIQUE)
    71SORT(JOIN)
    87TABLEACCESS(FULL)OF'C'
    
    selectA.col4
    fromB,A,C
    whereA.col1=B.col1
    andA.col2=C.col2;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=RULE
    10MERGEJOIN
    21SORT(JOIN)
    32NESTEDLOOPS
    43TABLEACCESS(FULL)OF'B'
    53TABLEACCESS(BYINDEXROWID)OF'A'
    65INDEX(RANGESCAN)OF'INX_COL12A'(NON-UNIQUE)
    71SORT(JOIN)
    87TABLEACCESS(FULL)OF'C'
    
    .Aªí¤Wªº¯Á¤Þinx_col12A.°£¦Z¡G
    selectA.col4
    fromB,A,C
    whereA.col1=B.col1
    andA.col2=C.col2;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=RULE
    10MERGEJOIN
    21SORT(JOIN)
    32MERGEJOIN
    43SORT(JOIN)
    54TABLEACCESS(FULL)OF'C'
    63SORT(JOIN)
    76TABLEACCESS(FULL)OF'A'
    81SORT(JOIN)
    98TABLEACCESS(FULL)OF'B'
    
    ³q.¤W­±ªº.¨Ç¨Ò¤l¡A¨Ï§Ú.oracle¤å.¤Wªº¡¨AllthingsbeingequalRBOchooses
    thedrivingorderbytakingthetablesintheFROMclauseRIGHTtoLEFT¡¨.¥y.«ùÊäºÃ.
    «×¡C¦¹.¡A§Ú¤]¤£¯à¨Ï¥Îhints..¨îɬ¤Æ¾¹¨Ï¥Înestedloop¡A¦pªG¨Ï¥Î¤Fhints¡A..´N
    ¦Û.¨Ï¥ÎCBOɬ¤Æ¾¹¡A¦Ó¤£¬ORBOɬ¤Æ¾¹¤F¡C
    
    .¤_CBOɬ¤Æ¾¹¡G
    CBO®ÚÕu..«H®§....ªí¡A°²¦p.¦³..«H®§¡A.¦bfrom¤l¥y¤¤.¥ª¨ì¥kªº.
    §Ç....ªí¡C.ÉORBO..ªº.§Ç¥¿¦n¬Û¤Ï¡C.¬O­^¤å­ì¤å(CBOdeterminesjoinorder
    fromcostsderivedfromgatheredstatistics.IftherearenostatsthenCBOchoosesthe
    drivingorderoftablesfromLEFTtoRIGHTintheFROMclause.ThisisOPPOSITEto
    theRBO)¡C§Ú.¬O.ªk...¥y.ªº¥¿ÚÌ©Ê¡C¤£.....¡G¡§¦pªG¥Îordered´£¥Ü(¦¹.
    ªÖ©w¥ÎCBO)¡A.¥Hfrom¤l¥y¤¤«ö.¥ª¨ì¥kªº.§Ç....ªí¡¨.¥y.¬O¥¿Ú̪º¡C..¤W¦b
    CBO¤¤¡A¦pªG¦³...Õu(§Y.ªíÉO¯Á¤Þ.¦æ¤F¤ÀªR)¡A.ɬ¤Æ¾¹.¦Û.®ÚÕucost­È.©wªö
    ¥Î­þÏú.±µ.«¬¡A¦}..¦XÓ쪺..ªí¡A.ÉOwhere¤l¥y¤¤¦U.­­¨î.¥óªº¦ì¸m.¦³¥ô¦ó
    .¨t¡C¦pªG§Ú.­n§ï.ɬ¤Æ¾¹..ªº.±µ.«¬©Î..ªí¡A.´N»Ý­n¨Ï¥Îhints¤F¡A¨ãÊ^hints
    ªº¥Îªk¦b¦Z­±..¤©¤¶.¡C
    
    ..¡G
    ¦pªG§Ú.«Øªº3.ªí¡G
    createtableA(col1number(4,0),col2number(4,0),col4char(30));
    createtableB(col1number(4,0),col3number(4,0),name_bchar(30));
    createtableC(col2number(4,0),col3number(4,0),name_cchar(30));
    createindexinx_col12Aona(col1,col2);
    
    .¦æ¬d.¡G
    selectA.col4
    fromB,A,C
    whereB.col3=10
    andA.col1=B.col1
    andA.col2=C.col2
    andC.col3=5;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=ALL_ROWS(Cost=3Card=1Bytes=110)
    10NESTEDLOOPS(Cost=3Card=1Bytes=110)
    21MERGEJOIN(CARTESIAN)(Cost=2Card=1Bytes=52)
    32TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    42SORT(JOIN)(Cost=1Card=1Bytes=26)
    54TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    61TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    
    selectA.col4
    fromB,A,C
    whereA.col1=B.col1
    andA.col2=C.col2;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=ALL_ROWS(Cost=5Card=55Bytes=4620)
    10HASHJOIN(Cost=5Card=55Bytes=4620)
    21HASHJOIN(Cost=3Card=67Bytes=4757)
    32TABLEACCESS(FULL)OF'B'(Cost=1Card=82Bytes=1066)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'C'(Cost=1Card=82Bytes=1066)
    
    .Aªí¤Wªº¯Á¤Þinx_col12A.°£¦Z¡G
    selectA.col4
    fromB,A,C
    whereA.col1=B.col1
    andA.col2=C.col2;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=ALL_ROWS(Cost=5Card=55Bytes=4620)
    10HASHJOIN(Cost=5Card=55Bytes=4620)
    21HASHJOIN(Cost=3Card=67Bytes=4757)
    32TABLEACCESS(FULL)OF'B'(Cost=1Card=82Bytes=1066)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'C'(Cost=1Card=82Bytes=1066)
    
    select/*+ORDERED*/A.col4
    fromC,A,B
    whereB.col3=10
    andA.col1=B.col1
    andA.col2=C.col2
    andC.col3=5;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=ALL_ROWS(Cost=3Card=1Bytes=110)
    10NESTEDLOOPS(Cost=3Card=1Bytes=110)
    21NESTEDLOOPS(Cost=2Card=1Bytes=84)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    ..¬d...¤F³q.ORDERED´£¥Ü¥i¥H¥¿Ú̪º´£¥Üɬ¤Æ¾¹..­þ.ªí§@.ɬ¤Æ¾¹¡C
    
    
    ¦p¦ó¤z..¦æ.¦E--¨Ï¥Îhints´£¥Ü
    °ò¤_¥NɲªºÉ¬¤Æ¾¹¬O«Ü.©úªº¡A¦b.¤j¦h.±¡.¤U¥¦...¥¿Ú̪ºÉ¬¤Æ¾¹¡A..¤FDBA
    ªº..¡C¦ý¦³.¥¦¤].©ú¤Ï³Q.©ú.¡A..¤F«Ü®tªº.¦æ.¦E¡A¨Ï¬Y..¥yªº.¦æ.±o©_ºC
    .¤ñ¡C¦¹.´N»Ý­nDBA.¦æ¤H.ªº¤z.¡A§i.ɬ¤Æ¾¹¨Ï¥Î§Ú.«ü©wªº¦s¨ú¸ô.©Î.±µ.«¬
    ¥Í¦¨.¦æ.¦E¡A.¦Ó¨Ï.¥y°ª®Äªº.¦æ¡C¨Ò¦p¡A¦pªG§Ú....¤_¤@.¯S©wªº.¥y¡A.¦æ¥þ
    ªí.´y­n¤ñ.¦æ¯Á¤Þ.´y§ó¦³®Ä¡A.§Ú.´N¥i¥H«ü¥Üɬ¤Æ¾¹¨Ï¥Î¥þªí.´y¡C¦bORACLE¤¤¡A
    ¬O³q...¥y²K¥[hints(´£¥Ü)...¤z.ɬ¤Æ¾¹É¬¤Æªº¥Øªº¡C
    
    hints¬Ooracle´£¨Ñªº¤@ÏúÉó¨î¡A¥Î.§i.ɬ¤Æ¾¹«ö·Ó§Ú.ªº§i.¥¦ªº¤è¦¡¥Í¦¨.¦æ.
    ¦E¡C§Ú.¥i¥H¥Îhints...¡G
    1)¨Ï¥ÎªºÉ¬¤Æ¾¹ªº.«¬
    2)°ò¤_¥NɲªºÉ¬¤Æ¾¹ªºÉ¬¤Æ¥Ø.¡A¬Oall_rows.¬Ofirst_rows¡C
    3)ªíªº..¸ô.¡A¬O¥þªí.´y¡A.¬O¯Á¤Þ.´y¡A.¬Oª½±µ§Q¥Îrowid¡C
    4)ªí¤§.ªº.±µ.«¬
    5)ªí¤§.ªº.±µ.§Ç
    6).¥yªº¦}¦æµ{«×
    
    °£¤F¡¨RULE¡¨´£¥Ü¥~¡A¤@¥¹¨Ï¥Îªº.ªº´£¥Ü¡A.¥y´N.¦Û.ªº§ï.¨Ï¥ÎCBOɬ¤Æ¾¹¡A¦¹
    .¦pªG§Aªº.Õu¦r¨å¤¤.¦³...Õu¡A´N.¨Ï¥Î¯Ê¬Ùªº...Õu¡C©Ò¥H«Ø.¤j®a¦pªG¨Ï¥Î
    CBO©ÎHINTS´£¥Ü¡A.³Ì¦n.ªí©M¯Á¤Þ.¦æ©w´Áªº¤ÀªR¡C
    
    ¦p¦ó¨Ï¥Îhints:
    Hints¥u.¥Î¦b¥¦.©Ò¦bsql.¥y.(statementblock¡A¥Ñselect¡Bupdate¡Bdelete..
    ¦r..)¤W¡A.¨ä¥¦SQL.¥y©Î.¥yªº¨ä¥¦³¡¤À.¦³¼v.¡C¦p¡G.¤_¨Ï¥Îunion¾Þ§@ªº2.
    sql.¥y¡A¦pªG¥u¦b¤@.sql.¥y¤W¦³hints¡A..hints¤£.¼v.¥t¤@.sql.¥y¡C
    
    §Ú.¥i¥H¨Ï¥Îª`.(comment)..¤@..¥y²K¥[hints¡A¤@..¥y.¥u¯à¦³¤@.ª`.¡A
    ¦Ó¥Bª`.¥u¯à©ñ¦bSELECT,UPDATE,orDELETE..¦rªº¦Z­±
    
    ¨Ï¥Îhintsªº.ªk¡G
    {DELETE|INSERT|SELECT|UPDATE}/*+hint[text][hint[text]]...*/
    or
    {DELETE|INSERT|SELECT|UPDATE}--+hint[text][hint[text]]...
    ª`¸Ñ¡G
    1)DELETE¡BINSERT¡BSELECT©MUPDATE¬O..¤@..¥y..©lªº..¦r¡A¥]§t
    ´£¥Üªºª`.¥u¯à¥X.¦b.¨Ç..¦rªº¦Z­±¡A§_.´£¥Ü.®Ä¡C
    2)¡§+¡¨.ªí¥Ü.ª`.¬O¤@.hints¡A.¥[.¥².¥ß§Y¸ò¦b¡¨/*¡¨ªº¦Z­±¡A¤¤.¤£¯à¦³ªÅ®æ¡C
    3)hint¬O¤U­±¤¶.ªº¨ãÊ^´£¥Ü¤§¤@¡A¦pªG¥]§t¦h.´£¥Ü¡A.¨C.´£¥Ü¤§.»Ý­n¥Î¤@.
    ©Î¦h.ªÅ®æ¹j.¡C
    4)text¬O¨ä¥¦.©úhintªºª`.©Ê¤å¥»
    
    ¦pªG§A.¦³¥¿Ú̪º«ü©whints¡AOracle.©¿²¤.hints¡A¦}¥B¤£..¥X¥ô¦ó..¡C
    
    
    ¨Ï¥Î¥þ®Mªºhints¡G
    .¨Ï¥Îhints.¡A¦b¬Y¨Ç±¡.¤U¡A.¤FÚÌ«O.ɬ¤Æ¾¹.¥Í³Ìɬªº.¦æ.¦E¡A§Ú.¥i¯à«ü
    ©w¥þ®Mªºhints¡C¨Ò¦p¡A¦pªG¦³¤@.Î`.ªº¬d.¡A¥]§t¦h.ªí.±µ¡A¦pªG§A¥u.¬Y.ªí«ü©w
    ¤FINDEX´£¥Ü(«ü¥Ü¦s¨ú¸ô.¦b.ªí¤W¨Ï¥Î¯Á¤Þ)¡Aɬ¤Æ¾¹»Ý­n..©w¨ä¥¦..¨Ï¥Îªº..
    ¸ô.©M¬Û.ªº.±µ¤èªk¡C¦]¦¹¡A§Y¨Ï§A.¥X¤F¤@.INDEX´£¥Ü¡Aɬ¤Æ¾¹¥i¯à.±o.¦³¥²­n
    ¨Ï¥Î.´£¥Ü¡C.¬O¥Ñ¤_§Ú..ɬ¤Æ¾¹..¤F¨ä¥¦.±µ¤èªk©M¦s¨ú¸ô.¡A¦Ó°ò¤_.¨Ç.±µ¤èªk
    ©M¦s¨ú¸ô.¡Aɬ¤Æ¾¹..¥Î..¥XªºINDEX´£¥Ü.¥Î¡C.¤F¨¾¤î.Ïú±¡.¡A§Ú.­n¨Ï¥Î¥þ
    ®Mªºhints¡A¦p¡G¤£¦ý«ü©w­n¨Ï¥Îªº¯Á¤Þ¡A¦Ó¥B¤]«ü©w.±µªº¤èªkÉO.±µªº.§Çµ¥¡C
    
    ¤U­±¬O¤@.¨Ï¥Î¥þ®Mhintsªº¨Ò¤l¡AORDERED´£¥Ü«ü¥X¤F.±µªº.§Ç¡A¦Ó¥B.¤£¦Pªº
    ªí«ü©w¤F.±µ¤èªk¡G
    SELECT/*+ORDEREDINDEX(b,jl_br_balances_n1)USE_NL(jb)
    USE_NL(glccglf)USE_MERGE(gpgsb)*/
    b.application_id,b.set_of_books_id,
    b.personnel_id,p.vendor_idPersonnel,
    p.segment1PersonnelNumber,p.vendor_nameName
    FROMjl_br_journalsj,jl_br_balancesb,
    gl_code_combinationsglcc,fnd_flex_values_vlglf,
    gl_periodsgp,gl_sets_of_booksgsb,po_vendorsp
    WHERE...
    
    «ü¥Üɬ¤Æ¾¹ªº¤èªkÉO¥Ø.ªºhints¡G
    ALL_ROWS--°ò¤_¥NɲªºÉ¬¤Æ¾¹¡A¥H§]¦R¶q.¥Ø.
    FIRST_ROWS(n)--°ò¤_¥NɲªºÉ¬¤Æ¾¹¡A¥H.....¥Ø.
    CHOOSE--®ÚÕu¬O§_¦³..«H®§¡A..¤£¦PªºÉ¬¤Æ¾¹
    RULE--¨Ï¥Î°ò¤_..ªºÉ¬¤Æ¾¹
    
    ¨Ò¤l¡G
    SELECT/*+FIRST_ROWS(10)*/employee_id,last_name,salary,job_id
    FROMemployees
    WHEREdepartment_id=20;
    
    SELECT/*+CHOOSE*/employee_id,last_name,salary,job_id
    FROMemployees
    WHEREemployee_id=7566;
    
    SELECT/*+RULE*/employee_id,last_name,salary,job_id
    FROMemployees
    WHEREemployee_id=7566;
    
    «ü¥Ü¦s.¸ô.ªºhints¡G
    FULL/*+FULL(table)*/
    «ü©w.ªí¨Ï¥Î¥þªí.´y
    ROWID/*+ROWID(table)*/
    «ü©w..ªí¨Ï¥Îrowid¦s¨ú¤èªk¡A.´£¥Ü¥Îªº.¤Ö
    INDEX/*+INDEX(table[index])*/
    ¨Ï¥Î.ªí¤W«ü©wªº¯Á¤Þ.ªí.¦æ¯Á¤Þ.´y
    INDEX_FFS/*+INDEX_FFS(table[index])*/
    ¨Ï¥Î§Ö³t¥þªí.´y
    NO_INDEX/*+NO_INDEX(table[index])*/
    ¤£¨Ï¥Î.ªí¤W«ü©wªº¯Á¤Þ.¦æ¦s¨ú¡A¤´µM¥i¥H¨Ï¥Î¨ä¥¦ªº¯Á¤Þ.¦æ¯Á¤Þ.´y
    
    SELECT/*+FULL(e)*/employee_id,last_name
    FROMemployeese
    WHERElast_nameLIKE:b1;
    
    SELECT/*+ROWID(employees)*/*
    FROMemployees
    WHERErowid>'AAAAtkAABAAAFNTAAA'ANDemployee_id=155;
    
    SELECT/*+INDEX(Asex_index)usesex_indexbecausetherearefew
    malepatients*/A.name,A.height,A.weight
    FROMpatientsA
    WHEREA.sex=¡¦m¡¦;
    
    SELECT/*+NO_INDEX(employeesemp_empid)*/employee_id
    FROMemployees
    WHEREemployee_id>200;
    
    «ü¥Ü.±µ.§Çªºhints:
    ORDERED/*+ORDERED*/
    «öfrom¦r¥y¤¤ªíªº.§Ç.¥ª¨ì¥kªº.±µ
    STAR/*+STAR*/
    «ü¥Üɬ¤Æ¾¹¨Ï¥Î¬P«¬¬d.
    
    SELECT/*+ORDERED*/o.order_id,c.customer_id,l.unit_price*l.quantity
    FROMcustomersc,order_itemsl,orderso
    WHEREc.cust_last_name=:b1
    ANDo.customer_id=c.customer_id
    ANDo.order_id=l.order_id;
    
    /*+ORDEREDUSE_NL(FACTS)INDEX(factsfact_concat)*/
    
    «ü¥Ü.±µ.«¬ªºhints¡G
    USE_NL/*+USE_NL(table[,table,...])*/
    ¨Ï¥Î´O®M.±µ
    USE_MERGE/*+USE_MERGE(table[,table,...])*/
    ¨Ï¥Î±Æ§Ç--¦X¦}.±µ
    USE_HASH/*+USE_HASH(table[,table,...])*/
    ¨Ï¥ÎHASH.±µ
    ª`·N¡G¦pªGªí¦³alias(.¦W)¡A.¤W­±ªºtable«üªº¬Oªíªº.¦W¡A¦Ó¤£¬O¯u.ªºªí¦W
    
    ¨ãÊ^ªº...¨Ò¡G
    createtableA(col1number(4,0),col2number(4,0),col4char(30));
    createtableB(col1number(4,0),col3number(4,0),name_bchar(30));
    createtableC(col2number(4,0),col3number(4,0),name_cchar(30));
    
    selectA.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE
    10MERGEJOIN
    21SORT(JOIN)
    32MERGEJOIN
    43SORT(JOIN)
    54TABLEACCESS(FULL)OF'B'
    63SORT(JOIN)
    76TABLEACCESS(FULL)OF'A'
    81SORT(JOIN)
    98TABLEACCESS(FULL)OF'C'
    
    select/*+ORDERED*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=5Card=1Bytes=110)
    10HASHJOIN(Cost=5Card=1Bytes=110)
    21HASHJOIN(Cost=3Card=1Bytes=84)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    
    select/*+ORDEREDUSE_NL(AC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=4Card=1Bytes=110)
    10HASHJOIN(Cost=4Card=1Bytes=110)
    21NESTEDLOOPS(Cost=2Card=1Bytes=84)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    
    .«Ø¯Á¤Þ¡G
    createindexinx_col12Aona(col1,col2);
    selectA.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE
    10MERGEJOIN
    21SORT(JOIN)
    32NESTEDLOOPS
    43TABLEACCESS(FULL)OF'B'
    53TABLEACCESS(BYINDEXROWID)OF'A'
    65INDEX(RANGESCAN)OF'INX_COL12A'(NON-UNIQUE)
    71SORT(JOIN)
    87TABLEACCESS(FULL)OF'C'
    
    select/*+ORDERED*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=5Card=1Bytes=110)
    10HASHJOIN(Cost=5Card=1Bytes=110)
    21HASHJOIN(Cost=3Card=1Bytes=84)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    
    select/*+ORDEREDUSE_NL(AC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=4Card=1Bytes=110)
    10HASHJOIN(Cost=4Card=1Bytes=110)
    21NESTEDLOOPS(Cost=2Card=1Bytes=84)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    
    select/*+USE_NL(AC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    §Ú...¬d.ªº·N«ä¬O.A¡BCªí°µNL.±µ¡A¦}¥B.Aªí§@..ªí¡A¦ý¬O..¦æ.¦E.¬Ý¡A
    .¦³.¨ì§Ú.ªº¥Øªº¡C
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=3Card=1Bytes=110)
    10NESTEDLOOPS(Cost=3Card=1Bytes=110)
    21MERGEJOIN(CARTESIAN)(Cost=2Card=1Bytes=52)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=1Bytes=26)
    42SORT(JOIN)(Cost=1Card=1Bytes=26)
    54TABLEACCESS(FULL)OF'B'(Cost=1Card=1Bytes=26)
    61TABLEACCESS(FULL)OF'A'(Cost=1Card=82Bytes=4756)
    
    ..¶H.¦æ¤ÀªR¦Z¡G
    analyzetableacomputestatistics;
    analyzetablebcomputestatistics;
    analyzetableccomputestatistics;
    analyzeindexinx_col12Acomputestatistics;
    selectA.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=5Card=8Bytes=336)
    10HASHJOIN(Cost=5Card=8Bytes=336)
    21MERGEJOIN(CARTESIAN)(Cost=3Card=8Bytes=64)
    32TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    42SORT(JOIN)(Cost=2Card=4Bytes=16)
    54TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    61TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    
    select/*+ORDERED*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=5Card=9Bytes=378)
    10HASHJOIN(Cost=5Card=9Bytes=378)
    21HASHJOIN(Cost=3Card=30Bytes=1140)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    
    select/*+ORDEREDUSE_NL(AC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=, CHOOSE(Cost=7Card=9Bytes=378)
    10HASHJOIN(Cost=7Card=9Bytes=378)
    21NESTEDLOOPS(Cost=5Card=30Bytes=1140)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    
    select/*+USE_NL(AC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=7Card=9Bytes=378)
    10HASHJOIN(Cost=7Card=9Bytes=378)
    21NESTEDLOOPS(Cost=5Card=30Bytes=1140)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    
    select/*+ORDEREDUSE_NL(ABC)*/A.col4
    fromC,A,B
    whereC.col3=5andA.col1=B.col1andA.col2=C.col2
    andB.col3=10;
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=35Card=9Bytes=378)
    10NESTEDLOOPS(Cost=35Card=9Bytes=378)
    21NESTEDLOOPS(Cost=5Card=30Bytes=1140)
    32TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    42TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    51TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    
    .¤_..¬d.§Ú..¦p¦ó¤].¦³±o¨ì.¦ü¤U­±..ªº.¦æ.¦E¡G
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=35Card=9Bytes=378)
    10NESTEDLOOPS(Cost=35Card=9Bytes=378)
    21TABLEACCESS(FULL)OF'B'(Cost=1Card=2Bytes=8)
    31NESTEDLOOPS(Cost=5Card=30Bytes=1140)
    43TABLEACCESS(FULL)OF'C'(Cost=1Card=4Bytes=16)
    53TABLEACCESS(FULL)OF'A'(Cost=1Card=30Bytes=1020)
    
    .¤W­±ªº.¨Ç¨Ò¤l§Ú.¥i¥H¬Ý¥X¡G³q...¥y²K¥[HINTS¡A.¨ä«ö·Ó§Ú.ªº·Nº@.¦æ¡A
    ¦³.¬O¤@¥ó«Ü§x.ªº¨Æ±¡¡A»Ý­n¤£.ªº..¦UÏú¤£¦Pªºhints¡C.¤_USE_NLÉOUSE_HASH
    ´£¥Ü¡A«Ø.¦PORDERED´£¥Ü¤@°_¨Ï¥Î¡A§_.¤£®e©ö«ü©w¨º.ªí...ªí¡C
    
    ¨ãÊ^®×¨Ò¤ÀªR¡G
    
    .¹Ò¡Goracle817+linux+.¦CÏ@
    swd_billdetailªí5000ÉE..Õu
    SUPER_USERªí2800..Õu
    .±µ¦C¤W³£¦³¯Á¤Þ¡A¦Ó¥Bsuper_user¤¤ªº¤@...¤_swd_billdetailªí¤¤ªº«Ü¦h...
    ªíÉO¯Á¤Þ³£°µ¤F¤ÀªR¡C
    
    ...¥Îªº¬d..¡G
    selecta.CHANNEL,B.user_class
    fromswd_billdetailB,SUPER_USERA
    whereA=B;
    
    ..¦b¤ÀªR..­P¬d.¥Xªº.Õu.¦h¡A¤£¤è«K¡A©Ò¥H¥Î
    count(a.CHANNEL||B.user_class).¥N´À¡A¦Ó¥Bcount(a.CHANNEL||B.user_class)¾Þ§@¥»
    ¨­¦}¤£¥e¥Î.¦hªº..¡A©Ò¥H¥i¥H±µ¨ü¦¹Ïú´À¥N¡C
    
    §Q¥Î¯Á¤Þ¬d.¥XSWD_BILLDETAILªí¤¤©Ò¦³..ªº¤èªk
    SQL>selectcount(id)fromSWD_BILLDETAIL;
    COUNT(ID)
    ----------
    53923574
    Elapsed:00:02:166.00
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=18051Card=1)
    10SORT(AGGREGATE)
    21INDEX(FASTFULLSCAN)OF'SYS_C001851'(UNIQUE)(Cost=18051Card=54863946)
    
    Statistics
    ----------------------------------------------------------
    0recursivecalls
    1952dbblockgets
    158776consistentgets
    158779physicalreads
    1004redosize
    295bytessentviaSQL*Nettoclient
    421bytesreceivedviaSQL*Netfromclient
    2SQL*Netroundtripsto/fromclient
    1sorts(memory)
    0sorts(disk)
    1rowsprocessed
    
    
    §Q¥Î¥þªí.´y.SWD_BILLDETAILªí¤¤¨ú¥X¥þ³¡.Õuªº¤èªk¡C
    SQL>selectcount(user_class)fromswd_billdetail;
    COUNT(USER_CLASS)
    -----------------
    53923574
    Elapsed:00:11:703.07
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=165412Card=1Bytes=2)
    10SORT(AGGREGATE)
    21TABLEACCESS(FULL)OF'SWD_BILLDETAIL'(Cost=165412
    Card=54863946Bytes=109727892)
    
    Statistics
    ----------------------------------------------------------
    0recursivecalls
    8823dbblockgets
    1431070consistentgets
    1419520physicalreads
    0redosize
    303bytessentviaSQL*Nettoclient
    421bytesreceivedviaSQL*Netfromclient
    2SQL*Netroundtripsto/fromclient
    1sorts(memory)
    0sorts(disk)
    1rowsprocessed
    
    
    selectcount(a.CHANNEL||B.user_class)
    fromswd_billdetailB,SUPER_USERA
    whereA=B;
    EXEC_ORDERPLANLINE
    ---------------------------------------------------------------------------------------------------------------------
    6SELECTSTATEMENTOPT_MODE:CHOOSE
    (COST=108968,CARD=1,BYTES=21)
    5SORT(AGGREGATE)(COST=,CARD=1,BYTES=21)
    4NESTEDLOOPS
    (COST=108968,CARD=1213745,BYTES=25488645)
    1TABLEACCESS(FULL)OF'SWORD.SUPER_USER'
    (COST=2,CARD=2794,BYTES=27940)
    3TABLEACCESS(BYINDEXROWID)OF
    'SWORD.SWD_BILLDETAIL'(COST=39,CARD=54863946,BYTES=603503406)
    2INDEX(RANGESCAN)OF'SWORD.IDX_DETAIL_CN'
    (NON-UNIQUE)(COST=3,CARD=54863946,BYTES=)
    
    ..¬d.¯Ó.ªº..«Ü.¡A»Ý­n1.¦h¤p.¡C
    .¦æ¦Zªº«H®§¦p¤U¡G
    COUNT(A.CHANNEL||B.USER_CLASS)
    ------------------------------
    1186387
    
    Elapsed:01:107:6429.87
    
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=108968Card=1Bytes=21)
    10SORT(AGGREGATE)
    21NESTEDLOOPS(Cost=108968Card=1213745Bytes=25488645)
    32TABLEACCESS(FULL)OF'SUPER_USER'(Cost=2
    Card=2794Bytes=27940)
    42TABLEACCESS(BYINDEXROWID)OF'SWD_BILLDETAIL'
    (Cost=39Card=54863946Bytes=603503406)
    54INDEX(RANGESCAN)OF'IDX_DETAIL_CN'(NON-UNIQUE)
    (Cost=3Card=54863946)
    
    Statistics
    ----------------------------------------------------------
    0recursivecalls
    4dbblockgets
    1196954consistentgets
    1165726physicalreads
    0redosize
    316bytessentviaSQL*Nettoclient
    421bytesreceivedviaSQL*Netfromclient
    2SQL*Netroundtripsto/fromclient
    2sorts(memory)
    0sorts(disk)
    1rowsprocessed
    
    ..¥y¤¤¥[¤Jhints¡A.oracleªºÉ¬¤Æ¾¹¨Ï¥Î´O®M´`.¡A¦}¥B¤jªí§@...ªí¡A¥Í¦¨·s
    ªº.¦æ.¦E¡G
    select/*+ORDEREDUSE_NL(A)*/count(a.CHANNEL||B.user_class)
    fromswd_billdetailB,SUPER_USERA
    whereA=B;
    
    EXEC_ORDERPLANLINE
    ---------------------------------------------------------------------------------------------------------------
    6SELECTSTATEMENTOPT_MODE:CHOOSE
    (COST=109893304,CARD=1,BYTES=21)
    5SORT(AGGREGATE)(COST=,CARD=1,BYTES=21)
    4NESTEDLOOPS
    (COST=109893304,CARD=1213745,BYTES=25488645)
    1TABLEACCESS(FULL)OF'SWORD.SWD_BILLDETAIL'
    (COST=165412,CARD=54863946,BYTES=603503406)
    3TABLEACCESS(BYINDEXROWID)OF
    'SWORD.SUPER_USER'(COST=2,CARD=2794,BYTES=27940)
    2INDEX(RANGESCAN)OF'SWORD.IDX_SUPER_USER_CN'
    (NON-UNIQUE)(COST=1,CARD=2794,BYTES=)
    
    ..¬d.¯Ó.ªº...µu¡A¤~20¤À.¡A©Ê¯à¤ñ.¦n¡C
    .¦æ¦Zªº«H®§¦p¤U¡G
    COUNT(A.CHANNEL||B.USER_CLASS)
    ------------------------------
    1186387
    
    Elapsed:00:20:1208.87
    
    ExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTOptimizer=CHOOSE(Cost=109893304Card=1
    Bytes=21)
    10SORT(AGGREGATE)
    21NESTEDLOOPS(Cost=109893304Card=1213745Bytes=25488645)
    32TABLEACCESS(FULL)OF'SWD_BILLDETAIL'(Cost=165412
    Card=54863946Bytes=603503406)
    42TABLEACCESS(BYINDEXROWID)OF'SUPER_USER'
    (Cost=2Card=2794Bytes=27940)
    54INDEX(RANGESCAN)OF'IDX_SUPER_USER_CN'
    (NON-UNIQUE)(Cost=1Card=2794)
    
    Statistics
    ----------------------------------------------------------
    0recursivecalls
    8823dbblockgets
    56650250consistentgets
    1413250physicalreads
    0redosize
    316bytessentviaSQL*Nettoclient
    421bytesreceivedviaSQL*Netfromclient
    2SQL*Netroundtripsto/fromclient
    2sorts(memory)
    0sorts(disk)
    1rowsprocessed
    
    ..¡G
    ¦].¤W..¬d.³£¬Oªö¥Înestedloop´`.¡A..ªö¥Î­þ.ªí§@.drivingtable´N«Ü
    ­«­n¡C¦b²Ä¤@.sql¤¤¡A¤pªí(SUPER_USER)§@.drivingtable¡A²Å¦Xoracleɬ¤Æªº«Ø.¡A
    ¦ý¬O¥Ñ¤_SWD_BILLDETAILªí¤¤cn¦Cªº­È¦³«Ü¦h­«Î`ªº¡A...¤_SUPER_USER¤¤ªº
    ¨C¤@¦æ¡A³£.¦bSWD_BILLDETAIL¤¤¦³«Ü¦h¦æ¡A§Q¥Î¯Á¤Þ¬d.¥X.¨Ç¦æªºrowid«Ü§Ö¡A¦ý
    ¬O¦A§Q¥Î.¨Çrowid¥h¬d.SWD_BILLDETAILªí¤¤ªºuser_class¦Cªº­È¡A´N¤ñ.ºC¤F¡C­ì
    ¦]¬O.¨Çrowid¬O.É󪺡A¦Ó¥B.ªí¤ñ.¤j¡A¤£¥i¯à.¦s¨ì.¦s¡A©Ò¥H¤L¥G¨C¦¸«ö·Órowid
    ¬d.³£»Ý­n.ª«²zºÏ.¡A.´N¬O..¦æ.¦E¤ñ.ºCªº¯u¥¿­ì¦]¡C..ªG¥i¥H±o¨ì..¡G¬d.
    ¥X1186387¦æ¡A»Ý­n§Q¥Îrowid.SWD_BILLDETAILªí¤¤.¨ú1186387¦¸¡A¦Ó¥B¤j³¡¤À
    ..µw.¤W.¨ú¡C
    
    ¤Ï¨ä¹D¦Ó¦æ¤§¡A§Q¥Î¤jªí(SWD_BILLDETAIL)§@.drivingªí¡A..¤jªí¥u»Ý­n°µ¤@
    ¦¸¥þªí.´y(¦Ó¥B.¨Ï¥Î¦h..¥\¯à¡A¨C¦¸ª«²zI/O³£..¨ú¤L.oracle.Õu.¡A.¦Ó¤@¦¸
    .¨ú«Ü¦h¦æ¡A¥[§Ö¤F.¦æ®Ä²v)¡A.¤_.¥Xªº¨C¤@¦æ¡A³£ÉOSUPER_USER¤¤ªº¦æ.¦æ¤Ç°t¡A
    ¦].SUPER_USERªí«Ü¤p¡A©Ò¥H¥i¥H¥þ³¡©ñ¨ì.¦s¤¤¡A..¤Ç°t¾Þ§@´NÌå§Ö¡A©Ò¥H.sql
    .¦æªº..ÉOSWD_BILLDETAILªí¥þªí.´yªº..®t¤£¦h(SWD_BILLDETAIL¥þªí¥Î11
    ¤À.¡A¦Ó¦¹¬d.¥Î20¤À.)¡C
    
    ¥t¥~¡G¦pªGSWD_BILLDETAILªí¤¤cn¦Cªº­È°ß¤@¡A.²Ä¤@.sql.¦æ.¦E.¦æªº.
    ªG©Î.¤].¤£.¡C¦pªGSUPER_USERªí¤]«Ü¤j¡A¦p500ÉE¦æ¡A.²Ä2.sql.¦æ.¦E.
    ¦æªº.ªG¤Ï¦Ó¤S¥i¯à.®t¡C¨ä.¡A¦pªGSUPER_USERªí«Ü¤p¡A.²Ä2.sql.¥yªº.¦æ
    .¦E¦pªG¤£§Q¥ÎSUPER_USERªíªº¯Á¤Þ¡A¬d.©Î..§ó§Ö¤@¨Ç¡A§Ú.¦³.¦¹.¦æ..¡C
    
    ©Ò¥H¦b.¦æ©Ê¯à.¾ã.¡A¨ãÊ^..­n¨ãÊ^¤ÀªR¡A.¦³¤@..¤@ªº.­ã¡C
    
    ²Ä6³¹¨ä¥¦ª`·N¨Æ.
    
    1.¤£­n...optimizer_mode....rule¡A´N..©Ò¦³ªº.¥y³£¨Ï¥Î°ò¤_..ªºÉ¬¤Æ¾¹
    ¤£ºÞoptimizer_mode..¦p¦ó.¸m¡A¥u­n.¨¬¤U­±3..¥ó¡A´N¤@©w¨Ï¥ÎCBO¡C
    1)¦pªG¨Ï¥ÎIndexOnlyTables(IOTs),¦Û.¨Ï¥ÎCBO.
    2)Oracle7.3¥H¦Z¡A¦pªGªí¤WªºParalledegreeoption..>1¡A
    .¦Û.¨Ï¥ÎCBO,¦Ó¤£ºÞ¬O§_¥Îrulehints.
    3)°£rlue¥H¥~ªº¥ô¦óhints³£..­P¦Û.¨Ï¥ÎCBO..¦æ.¥y
    
    ..¤@¤U¡A¤@..¥y¦b.¦æ.¨ì©³¨Ï¥Î¦óÏúɬ¤Æ¾¹¥i¥H.¤U­±ªºªí®æ¤¤..¥X.¡A.¤W
    ¨ì¤U¬Ý§Aªº.¥y¨ì©³¬O§_.¨¬description¦C¤¤´y­zªº.¥ó¡G
    Description.¶H¬O§_³Q¤ÀªRɬ¤Æ¾¹ªº.«¬
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Non-RBOObject(Eg:IOT)n/a#1
    Parallelism>1n/a#1
    RULEhintn/aRULE
    ALL_ROWShintn/aALL_ROWS
    FIRST_ROWShintn/aFIRST_ROWS
    *OtherHintn/a#1
    OPTIMIZER_GOAL=RULEn/aRULE
    OPTIMIZER_GOAL=ALL_ROWSn/aALL_ROWS
    OPTIMIZER_GOAL=FIRST_ROWSn/aFIRST_ROWS
    OPTIMIZER_GOAL=CHOOSENORULE
    OPTIMIZER_GOAL=CHOOSEYESALL_ROWS
    
    #1ªí¥Ü°£«DOPTIMIZER_GOAL³Q.¸m.FIRST_ROWS¡A§_..¨Ï¥Î
    ALL_ROWS¡C¦bPL/SQL¤¤¡A.¤@ª½¬O¨Ï¥ÎALL_ROWS
    
    *OtherHintªí¥Ü¬O«ü°£RULE¡BALL_ROWS©MFIRST_ROWS¥H¥~ªº¨ä¥¦´£¥Ü
    
    2).CBO..¤F¤@.¦¸É¬¤Æªº.¦æ.¦E.,¤£­n¦PCBO.·N¤£¥h,¥ýªö¨ú¦p¤U±¹¬I:
    a).¬d¬O§_¦bªíÉO¯Á¤Þ¤W¤S³Ì·sªº...Õu
    b).©Ò¦³ªº.Õu.¦æ¤ÀªR¡A¦Ó¤£¬O¥u¤ÀªR¤@³¡¤À.Õu
    c).¬d¬O§_¤Þ¥Îªº.Õu¦r¨åªí¡A¦boracle10G¤§«e¡A¯Ê¬Ù±¡.¤U¬O¤£..Õu¦r¨åªí
    .¦æ¤ÀªRªº¡C
    d)..RBOɬ¤Æ¾¹¡A¬Ý.¥y.¦æªº®Ä²v¦p¦ó¡A¦³.RBO¯à¤ñCBO.¥Íªº§ó¦nªº.
    ¦æ.¦E
    e)¦pªG.¤£¦æ¡A¸ò...¥yªº.¦æ¡A¥Í¦¨trace«H®§¡AµM¦Z¥Îtkprof®æ¦¡¤Ætrace«H
    ®§¡A..¥i¥H±o¨ì¥þ­±ªº¨Ñɬ¤Æªº«H®§¡C
    
    3)°²¦p§Q¥Îªþ.ªº¤èªk.¥t¤@....¦ætrace¡A........¥Î.±µ
    
    4)¤£­n...©w.¶q(bindvariables)ªº¯Ê.¥u¦³..³Â.¡A¦Óɬ.¦h¦h¡A..¤W¨Ï¥Î.©w
    .¶q.µMÁקK¤F­«Î`parse¡A¦ý¬O¥¦.­Pɬ¤Æ¾¹¤£¯à¨Ï¥Î.Õu.¤¤ªº¦C..¡A.¦Ó..¤F.
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    .Ïú±¡..±o¨ì§ïµ½¡C¥Ø«e´N¤w...¤F¦b²Ä¤@¦¸.¦æ.©w.¶qªºsql.¥y.¡A¦Ò.¦C..¡C
    
    5)¦pªG¤@.rowsource¶W.10000¦æ.Õu¡A.¥i¥H³Q..¤jrowsource
    
    6)¦³(+)ªºªí¤£¬Odrivingtable¡Aª`·N¡G¦pªG¦³¥~.±µ¡A¦Ó¥Borderhint«ü©wªº.§ÇÉO¥~..
    .©wªº.§Ç.¬ð¡A.©¿²¤orderhint
    
    7)¼v.CBO..executionplanªºªì©l¤Æ..:
    .¨Ç...¼v.cost­È
    ALWAYS_ANTI_JOIN
    B_TREE_BITMAP_PLANS
    COMPLEX_VIEW_MERGING
    DB_FILE_MULTIBLOCK_READ_COUNT
    FAST_FULL_SCAN_ENABLED
    HASH_AREA_SIZE
    HASH_JOIN_ENABLED
    HASH_MULTIBLOCK_IO_COUNT
    OPTIMIZER_FEATURES_ENABLE
    OPTIMIZER_INDEX_CACHING
    OPTIMIZER_INDEX_COST_ADJ
    OPTIMIZER_MODE>/GOAL
    OPTIMIZER_PERCENT_PARALLEL
    OPTIMIZER_SEARCH_LIMIT
    PARTITION_VIEW_ENABLED
    PUSH_JOIN_PREDICATE
    SORT_AREA_SIZE
    SORT_DIRECT_WRITES
    SORT_WRITE_BUFFER_SIZE
    STAR_TRANSFORMATION_ENABLED
    V733_PLANS_ENABLED
    CURSOR_SHARING
    
    
    ªþ.¡G
    ¦p¦ó³q.¸ò.¤@.«È.ºÝµ{§Ç.¥Xªºsqlªº¤èªk.ɬ¤ÆSQL
    
    .­n..¡A¸ò.¤@.«È.µ{§Ç.¥XªºSQL¥D­n¤À¦¨¤U­±¤L¨B¡G
    1)..­n¸ò.ªº«È.ºÝµ{§Ç¨ì.Õu.ªº.±µ(¦Z­±³£¥Îsession¥N´À)¡A¥D­n§ä¥X¯à°ß¤@.
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    2).©w¬Û.ªº..¡A¦p¥´.....(¥i¥Hª¾¹D¤@.sql.¦æ¤F¦h...)¡A¦s©ñ¸ò..Õu
    ªº¤å¥óªº¦ì¸m¡B³Ì¤j­È¡C
    3)..¸ò.¥\¯à
    4).¨t..¦æ¤@¬q..¡A¥H«K¥i¥H¦¬¶°¨ì¸ò..Õu
    5)..¸ò.¥\¯à
    6)®æ¦¡¤Æ¸ò..Õu¡A±o¨ì§Ú.©ö¤_²z¸Ñªº¸ò..ªG¡C
    
    .¦b´N¨C¤@¨B¡A.¥X..ªº.©ú¡G
    1)..­n¸ò.ªº«È.ºÝµ{§Ç¨ì.Õu.ªº.Õu..±µ
    ¬d.session«H®§(¦bsql*plus¤¤.¦æ)¡G
    setlinesize190
    colmachineformata30wrap
    colprogramfora40
    colusernameformata15wrap
    setpagesize500
    selects.sidsid,s.SERIAL#"serial#",s.username,s.machine,s.program,
    p.spidServPID,s.server
    fromv$sessions,v$processp
    wherep.addr=s.paddr;
    
    ¦p±o¨ìªº¤@.¬d..ªG¦p¤U¡G
    SIDserial#USERNAMEMACHINEPROGRAMSERVPIDSERVER
    --------------------------------------------------------------------
    83SCOTTWORKGROUP\SUNNYXUSQLPLUS.EXE388DEDICATED
    
    LOGON_TIME
    ------------------
    2005.06.2818:50:11
    
    ¤W­±ªº.ªG¤¤¤ñ.¦³¥Îªº¦C.¡G
    sid,serial#:...­È.¦X°_.°ß¤@..¤@.session
    username:µ{§Ç.±µ.Õu.ªº¥Î.¦W
    machine:.±µ.Õu.ªºµ{§Ç©Ò¦bªºÉ󾹪ºÉ󾹦W¡A¥i¥Hhostname±o¨ì
    program:.±µ.Õu.ªºµ{§Ç¦W¡A©Ò¦³¥Îjavajdbcthinªºµ{§Çªº¦W¦r³£¤@.¡A
    servpid:ÉOµ{§Ç..ªºªA.¾¹ºÝªºªA.¾¹.µ{ªº.µ{.¡A¦bunix¤U¤ñ.¦³¥Î
    server:µ{§Ç.±µ.Õu.ªº¼Ò¦¡¡G.¥Î¼Ò¦¡(dedicaed)¡B¦@¨É¼Ò¦¡(shared)¡C
    ¥u¦³¦b.¥Î¼Ò¦¡¤Uªº.Õu..±µ¡A.¨ä.µ{¸ò.¤~¦³®Ä
    logon_time:µ{§Ç.±µ.Õu.ªºµn...
    
    ®ÚÕumachine,logon_time¥i¥H¤è«Kªº..¥X¤@..Õu..±µ..ªºsession¡A.¦Ó±o¨ì.
    sesionªº°ß¤@..sid,serial#,...session.¦æ¸ò.°µ¦n­ã.
    
    2).©w¬Û.ªº..
    ...©ú¡G
    timed_statistics:¦¬¶°¸ò.«H®§.¡A¬O§_.¦¬¶°..«H®§¡A¦pªG¦¬¶°¡A
    .¥i¥Hª¾¹D¤@.sqlªº¦U..¦æ.¬q¯Ó.ªº..±¡.
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    max_dump_file_size:©ñ¸ò..Õuªº¤å¥óªº³Ì¤j­È¡A¨¾¤î¥Ñ¤_.·Nªº²¨©¿¡A
    ¨Ï¸ò..Õuªº¤å¥ó¥e¥Î¾ã.µw.¡A¼v.¨t.ªº¥¿±`.¦æ
    
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    SQL>execsys.dbms_system.set_bool_param_in_session(-
    sid=>8,-
    serial#=>3,-
    parnam=>'timed_statistics',-
    bval=>true);
    
    SQL>altersystemsetuser_dump_dest='c:\temp';
    --ª`·N...¥y.§ï.¾ã.¨t.ªº¸ò.¤å¥ó¦s©ñªº¦ì¸m¡A©Ò¥H§Ú¤@¯ë¤£§ï....¡A¦Ó¥Î
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    SQL>execsys.dbms_system.set_int_param_in_session(-
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    intval=>2147483647)
    
    3)..¸ò.¥\¯à
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    4).¨t..¦æ¤@¬q..¡A¥H«K¥i¥H¦¬¶°¨ì¸ò..Õu
    
    5)..¸ò.¥\¯à
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    sort='(prsela,exeela,fchela)'
    (c)tkproftracefile.trcsort_3.prfexplain=apps/your_apps_passwordprint=10
    sort='(prscnt,execnt,fchcnt)'
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    .¦æ.¦E¡G
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    ¤@..¥yªº.¦æ.¦E¬Ooracle.¦æ..sql.¥yªº¤@¨t¦C«ü¥O¡C³q....¦æ.¦E¡A§A
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    TKPROFªº¨Ï¥Î.ªk¡G
    ----------------
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    ||
    +-SORT=---------------------------------+
    ||
    +--OPTION--+
    ||
    |+----,----+|
    |V||
    |__(OPTION)__|
    
    >----------------------------------------------------------------------------->
    ||||||
    +--PRINT=integer--++--INSERT=filname3--++--SYS=---------+
    ||
    +-YES-+
    ||
    +-NO--+
    
    >----------------------------------------------------------------------------->
    ||
    +----------------------------------------EXPLAIN=user/password------+
    ||
    +----TABLE=schema.table----+
    
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    ||
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    ¦U...ªº§t.¡G
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    «ü©w.¤J¤å¥ó¡A§Yoracle.¥Íªºtrace¤å¥ó¡A.¤å¥ó¤¤¥i¥H¥u¥]§t¤@.
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    ¦b.sql.¥y.¦æ¤ÀªR.¡A..¥Íªº.¦æ.¦E..¦s©ñ¨ì.ªí¤¤¡C
    ¤@¯ë¤£»Ý­n...¡A...ªí¤£¦s¦b.¡Atkprof.¦Û..«Ø¬Û.ªºªí¡A
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    §Ú¤@¯ë..NO¡A...¥X¤å¥ó¤¤¥u¥]§t§Ú.¥Xªºsql.¥y¡A
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    .«ö·Ó¨Ï¥Îsqlªº¥ý¦Z.§Ç¡C
    ±Æ§Ç..¦³¡G
    prscntnumberoftimesparsewascalled
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    prselaelapsedtimeparsing
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    prsqrynumberofbuffersforconsistentreadduringparse
    prscunumberofbuffersforcurrentreadduringparse
    prsmisnumberofmissesinlibrarycacheduringparse
    execntnumberofexecutewascalled
    execpucputimespentexecuting
    exeelaelapsedtimeexecuting
    exedsknumberofdiskreadsduringexecute
    exeqrynumberofbuffersforconsistentreadduringexecute
    execunumberofbuffersforcurrentreadduringexecute
    exerownumberofrowsprocessedduringexecute
    exemisnumberoflibrarycachemissesduringexecute
    fchcntnumberoftimesfetchwascalled
    fchcpucputimespentfetching
    fchelaelapsedtimefetching
    fchdsknumberofdiskreadsduringfetch
    fchqrynumberofbuffersforconsistentreadduringfetch
    fchcunumberofbuffersforcurrentreadduringfetch
    fchrownumberofrowsfetched
    useriduseridofuserthatparsedthecursor
    
    PRINT
    ¥u¦C¥X«ü©w.¶qªº¤w±Æ§Çªºsql.¥y¡A±Æ§Çªº.¥ó..SORT..¡C
    ¦pªG©¿²¤¦¹..¡Atkprof.¸ò.¤å¥ó¤¤ªº©Ò¦³ªºsql.¥y¤Î¨ä¬Û.ªº
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    §ä¥X¬Y¤@.¬q.µw.³Ì¦hªº«en.sqlµ¥µ¥¡C
    
    INSERT
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    §Q¥Î...¥»¤å¥ó.«Ø¤@.ªí¤Î´¡¤J.Õu¦Z¡A¥i¥H±o¨ì¸ò.¤å¥ó¤¤
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    §Q¥Î.¨Ç«H®§¡A¤]¥i¥H..¦³..ªºsql¡C§Y¬O®æ¦¡¤Æ¦nªº.¥X¤å¥ó¤¤
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    .«Ø¤@.¥]§t«È.ºÝµ{§Ç.¥Xªº©Ò¦³ªºsql.¥yªº.¥»¤å¥ó¡C
    ª`·N¡A¦}¤£¥]§trecursiveSQL¡C·Qª¾¹D¥¦ªº¥Î..¡H
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    ¤W­±ªº¨Ò¤l¤¤¡G
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    ª`·N¤W­±ªº©Ò¦³©R¦W..³£¦b¤@¦æ¤¤¡A§_.»Ý­n¦³.¦æ²Å¡C
    
    ¤W­±ªº¨Ò¤l¤¤¡G
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    Tracefile:D:\oracle\admin\xyj\udump\ORA01720.TRC
    Sortoptions:default
    
    ********************************************************************************
    count=numberoftimesOCIprocedurewasexecuted
    cpu=cputimeinsecondsexecuting
    elapsed=elapsedtimeinsecondsexecuting
    disk=numberofphysicalreadsofbuffersfromdisk
    query=numberofbuffersgottenforconsistentread
    current=numberofbuffersgottenincurrentmode(usuallyforupdate)
    rows=numberofrowsprocessedbythefetchorexecutecall
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    body¡G
    ¬O§Ú.¥D­n.¤ßªº¦a¤è¡A¦³§Ú.·P.½ìªº«H®§¡C¦psql.¥y¡Bsql.¥yªº..«H®§¡Bsql.¥y
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    select*
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    ------------------------------------------------
    Parse30.000.001010
    Execute30.000.000000
    Fetch60.000.00161236
    ------------------------------------------------
    total120.000.00261336
    
    Missesinlibrarycacheduringparse:1
    Optimizergoal:CHOOSE
    Parsinguserid:19(SCOTT)
    
    RowsRowSourceOperation
    ----------------------------------------------------------
    12TABLEACCESSFULLEMP
    
    RowsExecutionPlan
    ----------------------------------------------------------
    0SELECTSTATEMENTGOAL:CHOOSE
    12TABLEACCESS(FULL)OF'EMP'
    
    
    DELETEFROMRM$HASH_ELMS
    callcountcpuelapseddiskquerycurrentrows
    --------------------------------------------------
    Parse20.000.000000
    Execute2912.0412.616786685310819
    Fetch00.000.000000
    --------------------------------------------------
    total3112.0412.616786685310819
    
    Missesinlibrarycacheduringparse:0
    Optimizerhint:CHOOSE
    Parsinguserid:9(DES12A)(recursivedepth:3)
    
    RowsExecutionPlan
    ----------------------------------------------------------
    0DELETESTATEMENTHINT:CHOOSE
    16TABLEACCESS(FULL)OF'RM$HASH_ELMS'
    
    summary¡G
    .©Ò¦³ªºsql.¥y¦U..¦æ.¬qªº...Õuªº..¡G
    
    OVERALLTOTALSFORALLNON-RECURSIVESTATEMENTS--.©ú¬O¥Î..¥Xªº
    sql.¥yªº...Õuªº..
    
    callcountcpuelapseddiskquerycurrentrows
    -----------------------------------------------------
    Parse70.000.00220120
    Execute70.000.001271
    Fetch100.000.002671652
    -----------------------------------------------------
    total240.000.0052702553
    
    Missesinlibrarycacheduringparse:5
    
    
    OVERALLTOTALSFORALLRECURSIVESTATEMENTS--.©ú¬O¨t..¥Xªºsql.¥y
    ªº...Õuªº..
    
    callcountcpuelapseddiskquerycurrentrows
    --------------------------------------------------
    Parse750.000.002320
    Execute810.000.001151
    Fetch1530.000.00213550110
    --------------------------------------------------
    total3090.000.00243597111
    
    Missesinlibrarycacheduringparse:29
    
    8userSQLstatementsinsession.
    74internalSQLstatementsinsession.
    82SQLstatementsinsession.
    5statementsEXPLAINedinthissession.
    *********************************************************************
    Tracefile:D:\oracle\admin\xyj\udump\ORA01720.TRC
    Tracefilecompatibility:8.00.04
    Sortoptions:default
    
    1sessionintracefile.
    8userSQLstatementsintracefile.
    74internalSQLstatementsintracefile.
    82SQLstatementsintracefile.
    34uniqueSQLstatementsintracefile.
    5SQLstatementsEXPLAINedusingschema:
    SCOTT.prof$plan_table
    Defaulttablewasused.
    Tablewascreated.
    Tablewasdropped.
    825linesintracefile.
    
    
    .¥u.body¤¤ªº¨C³¡¤À§@¥X...©ú¡G
    1)sql.¥yªº..«H®§
    §Ú.§âselect.¥yªº.¦æ.µ{¤À¦¨3..¬q(¤ÀªR...¦æ..¨ú.ªG)¡A§âDML.¥yªº
    .¦æ¤À¦¨2..¬q(¤ÀªR...¦æ)¡C®æ¦¡¤Æªº.¥X¤å¥ó¤¤¦C¥X¤Fsql.¥y.¦æªº¨C¤@.¬q©Ò¯Ó
    ..·½..«H®§¡A.¤_.¨Ç«H®§¡A¬O¥H¦æ¦Cªº¼Ò¦¡.¥Xªº¡C¨C¤@¦æ¥Nªí¨C.sql.¦æ¤¤ªº¨ã
    Ê^¬Y¤@.¬q©Ò¯Ó.ªº¬Û..·½¡C..³q.¤ÀªR¨C..¬q¯Ó.ªº.·½¡A¥i¥Hª¾¹D­þ.sql¦³.
    .¡A¦}.¤@¨Bª¾¹D.sql.¦æ.µ{¤¤­þ¤@.¬q¥X.¤F..¡A.¦Ó§Ö³t©w¦ì..¡A.¦Ó¨³³t¸Ñ
    ...¡C
    
    ¤U­±.¨C.¦C.¦æ.©ú¡G
    call:ªí¥Üsql.¥y.¦æªº¨C..¬q¡A¨C.sql.¥yªº¬¡.³Q¤À¦¨¥H¤U3³¡¤À¡G
    Parse:.¥y³Q¸ÑªRªº¦¸.¡A¥D­n¬O¥Í¦¨.¦æ.¦E¡C¥]§thardparseÉOsoftparse¡C
    »Ý­n°µªº¤u§@¡G.­­.¬d¡Aªí¡B¦C¡B¤Þ¥Îªºªíªº¦s¦b©Ê.¬d¡F
    ¤ñ..¦æ.¦E¡A.¥X³Ì¦nªº¤@.µ¥µ¥¡C
    Execute:¯u¥¿.¦æ.¥yªº..¡A.¤_DML.¥y¡A¦b¦¹.¬q¤¤­×§ï.Õu¡F
    .¤_select.¥y¡A.¨B¥u¬O..¥X¬d.¥Xªº¦æ¡C
    Fetch:¥u.select.¥y¦³®Ä¡ADML.¥yªº.¦æ¦}.¦³..¬q
    
    ¨ä¥¦¦Cªº­È³£¬OÉOsql.¦æ¤T..¬q¤¤©Ò¯Ó.ªº.·½ªº..­È
    COUNT
    ¤@..¥y³Qparsed¡Bexecuted¡Bfetchedªº¦¸.
    CPU
    .¦æ...¥yªº¨C..¬q¯Ó.ªºcpu..
    ELAPSED
    .¦æ...¥yªº¨C..¬q¯Ó.ªº...(¥]¬A¤W­±ªºcpu..ÉO¨ä¥¦..¡A¦p..Õu)
    DISK
    ¨C..¬q.µw.ªº¦¸.(¦³¥i¯à.filesystembuffer¤¤¨ú±o.Õu)
    .¤_...¡A§Ú.§Æ±æ.­È¶V¤p¶V¦n¡A¦pªG.­È«Ü¤j¡A.sql»Ý­n.¾ã¡A
    «Ø¥ß¬Û.¯Á¤Þ©Î¬Ý¬O§_¥¿Ú̪º¨Ï¥Î¤F¯Á¤Þ
    QUERY
    ¨C..¬q¥Hconsistentmode¤è¦¡..Õu.buffer¤¤¬d.ªºbuffers.¡C
    .¤_¬d.¡A¨äbuffer¤@¯ë³£¬O¥Hconsistentmode¼Ò¦¡³Q.¨ú
    CURRENT
    ¨C..¬q¥Hcurrentmode¤è¦¡..Õu.buffer¤¤¬d.ªºbuffers.¡CBuffersareoften
    .¤_DML.¥y¡A»Ý­nªºbuffer¬O¥Hcurrentmode¼Ò¦¡³Q.¨úªº¡C
    QUERY+CURRENTªº©M¬O.sql.¥y.ªº¦s¨úªºbuffer.¥Ø
    ROWS
    ..sql.¥y³Ì¦Z.²zªº¦æ.¡A¤£¥]¬A¤l¬d.¤¤¬d.¥X.ªº¦æ.¡C
    .¤_select.¥y¡A.­È.¥Í¤_fetch.¬q¡F.¤_dml.­È.¥Í¤_execute.¬q¡C
    
    ¦]...¯Ó.ªº...¡A³Ì¤pªº.¶q.¦ì.0.01¬í¡A©Ò¥H¦pªG±o¨ì¤@..¬q¤¤¯Ó.ªº
    ...0¡A¦}¤£ªí¥Ü...¬q.¦³¯Ó...¡A¦Ó¬OÌå¥i¯à.©ú...¬q¯Ó.ªº..¤p¤_0.01
    ¬í¡A¤p¤_.¶q.¦ì¡A.Õu..ªk..¡A¥u­n¥H0.00ªí¥Ü
    
    2)ÉO.¦æ.¦E¦³.ªº.®e
    Missesinlibrarycacheduringparse:1--.©úhardparseªº¦¸.
    Optimizergoal:CHOOSE--ªö¥ÎªºÉ¬¤Æ¾¹
    Parsinguserid:19(SCOTT)--¨º.¥Î..¦æªº.sql
    
    RowsRowSourceOperation
    ----------------------------------------------------------
    12TABLEACCESSFULLEMP
    
    RowsExecutionPlan--¤U­±¬O¯u¥¿ªº.¦æ.¦E
    ----------------------------------------------------------
    0SELECTSTATEMENTGOAL:CHOOSE
    12TABLEACCESS(FULL)OF'EMP'
    
    Missesinlibrarycacheduringparse:....­È¬O¤@.¤ñ.­«­nªº«ü.¡A¦pªG.­ÈÉO
    ..¥yªºparse..­È°ò¥»¬Ûµ¥¡A¦}¥B.­È¤ñ.¤j¡A¦Ó¥B.sqlªºparse.¬q¯Ó.ªº.·½
    ¤ñ.¦h¡A..©ú§Aªº.¥y..ªö¥Îbindvariable¼Ò¦¡¡C
    
    .¦æ.¦E³¡¤À¤]¤ñ.­«­n¡A¥¦¯à¬Ý¥X¬d.¬O§_¥Î¤F¯Á¤Þ¡A©M¦UÏú..¾Þ§@©Òªö¥Îªº¤èªk¡C
    
    «Ø.¥Îautotrace.¦æ¸ò.¦Ó¤£¬O¥Î¤W­±¤èªk.¦æ¸ò.ªº­ì¦]¡G
    .µM¤W­±ªº¤èªk.¥X¤Fsql.¥yªº.¦æ.¦E¡B...Õuµ¥«H®§¡A¦ý¬O¦].tkprofªº®æ¦¡
    ¤Æ.¥X¤£.¥X..ªºcostsÉOstatistics«H®§¡A.¨Ï§Ú.¦b§Q¥Î®æ¦¡¤Æ.¥X§P.¨t.¨ì©³¬O
    ¨Ï¥Î°ò¤_¥NɲªºÉ¬¤Æ¤èªk.¬O°ò¤_..ªºÉ¬¤Æ¤èªk.¡A·P¨ì«Ü°g¯í¡A§Ú.¤£¯à©úÚ̪ºª¾¹D¨ì
    ©³¨t.¦b¨Ï¥Î¨ºÏúɬ¤Æ¾¹¡C
    
    ¦ý¬O..¦]...­ì¦]´N¨Ï§Ú.©ñ.¤W­±¸ò.¤èªk¦Ó.¥Îautotrace¥\¯à¬O¤£.ªº¡A¦].¡G
    1)¨ì©³¨t.¬O¨Ï¥Î°ò¤_..ªº.¬O°ò¤_¥NɲªºÉ¬¤Æ¾¹§Ú.¥i¥H­É§UÉO¨ä¥¦«H®§...¡A¦Ó
    ¥B.10G¥H¦Z¡Aoracle´N«Å¥¬¤£¦A¨Ï¥Î°ò¤_..ªºÉ¬¤Æ¾¹¤F¡C
    2)¤W­±ªº¸ò..ªk¯à..autotrace¤£¯à§¹¦¨ªº¥\¯à¡A¦].autotrace¥u¯à¸ò.¥»..¡A¦Ó
    ¤£¯à¸ò.¨ä¥¦..¡A..°²¦p¦³¤@.¥¿¦b.¦æªºµ{§Ç¥X.¤F©Ê¯à..¡A§Ú.´N¤£¯à¨Ï¥Î
    autrace¥h¸ò.sqlªº.¦æ±¡.¡C
    
    
    ¤U­±¥H¤@.¨ãÊ^ªº¨Ò¤lªº.Õu.©ú¦p¦ó§Q¥Î®æ¦¡¤Æªº.¥X¤å¥ó.¦æsqlªº.¾ã¡G
    
    ²Ä¤@¨B¡G-.¬Ý®æ¦¡¤Æ.¥X¤å¥ó³Ì¦Z³¡¤À¡A§Y..³¡¤À
    ===========================================================
    OVERALLTOTALSFORALLNON-RECURSIVESTATEMENTS
    
    |call|count|cpu|elapsed|disk|query|current|rows|
    |---------|-------|------|---------|---------|--------|---------|--------|
    |Parse|[A]7|1.87|4.53|385|[G]553|22|0|
    |Execute|[E]7|0.03|0.11|[P]0|[C]0|[D]0|[F]0|
    |Fetch|[E]6|1.39|4.21|[P]182|[C]820|[D]3|[F]20|
    --------------------------------------------------------------------------
    
    Missesinlibrarycacheduringparse:5
    Missesinlibrarycacheduringexecute:1
    
    8userSQLstatementsinsession.
    12internalSQLstatementsinsession.
    [B]54SQLstatementsinsession.
    3statementsEXPLAINedinthissession.
    
    (1).³q.¤ñ.[A]ÉO[B]¡A§Ú.¥i¥H..¬O§_¦³.¶qªºparsing.¶H¡C¦b¤W­±ªº¨Ò¤l¤¤¡A§Ú
    .¥i¥H¬Ý¨ì¦bsession¤¤.¦æ¤F54..¥y¡A¦ý¬O¥u¦³7¦¸parses¡A©Ò¥H.¬O¤ñ.¥¿±`ªº¡A
    .¦³.¶qªºparse.¶H¡C
    
    (2).§Q¥Î[P],[C]&;[D]..©w.Õu.°ª³t.¦sªº©R¤¤²v..
    HitRatioislogicalreads/physicalreads:
    LogicalReads=ConsistentGets+DBBlockGets
    LogicalReads=query+current
    LogicalReads=Sum[C]+Sum[D]
    LogicalReads=0+820+0+3
    LogicalReads=820+3
    LogicalReads=823
    
    HitRatio=1-(PhysicalReads/LogicalReads)
    HitRatio=1-(Sum[P]/LogicalReads)
    HitRatio=1-(128/823)
    HitRatio=1-(0.16)
    HitRatio=0.84or84%
    
    (3).§Ú.§Æ±æfetchªº¦¸.­n¤ñrows¤p¡A§Y¤@¦¸fetch¥i¥H¨ú¦h¦æ.Õu(arrayfetching)¡A
    ¥i¥H§Ú.¥i¥H§ó°ª®Äªº¨ú±o¬d..Õu¡C
    .¥i¥H³q.¤ñ.[E]ÉO[F].
    
    [E]=6=NumberofFetches
    [F]=20=NumberofRows
    
    .¤W­±ªº«H®§¤¤§Ú.¥i¥H¬Ý¨ì¡A6¦¸fetch.¦@¨ú¤F20¦æ.Õu¡A.ªG¤£¬O«Ü§¥¡C¦pªG¨Ï¥Î
    ¤F..¨}¦n°t¸marrayfetching¡A.¥i¥H¥Î§ó¤Öªºfetch¦¸.¨ú¨ì¦P..¶qªº.Õu¡A©Ê¯à.§ó
    ¦n¡C
    
    (4).[G]ªí¥Ü.¤F..¥y.¦æ¤ÀªR¡A..Õu¦r¨å§i..¦sªº¦¸.
    -.....©Ê¯àªº¼v.¤£¤j¡A¤@¯ë¤£¥Î.¤ß¡C¦Ó¥B....­È¤@¯ë¤£¬O§Ú.¥i¥H±±¨î
    ªº¡C
    
    ²Ä¤G¨B¡V.¬d¯Ó.¤j¶q.·½ªº.¥y
    ===============================================
    update...
    where...
    
    |call|count|cpu|elapsed|disk|query|current|rows|
    |---------|-------|-----|---------|------|--------|---------|--------|
    |Parse|1|7|122|0|0|0|0|
    |Execute|1|75|461|5|[H]297|[I]3|[J]1|
    |Fetch|0|0|0|0|0|0|0|
    -----------------------------------------------------------------------
    
    [H]ªí©ú»Ý­n..297..Õu.¤~¯à§ä¨ì§Ú.»Ý­n­×§ïªº.Õu¡C
    [I]ªí©ú§Ú.ªº­×§ï¾Þ§@¤~­×§ï3..Õu.¤¤ªº.Õu
    [J]ªí©ú§Ú.¥u­×§ï¤F¤@¦æ.Õu(¨ä¥¦.Õu.ªº­×§ï..undo¡Bredo«H®§)
    
    .¤F­×§ï¤@¦æ.Õu¦Ó­n·j.297..Õu.¡C
    ¦Ò.¬O§_»Ý­n¦b¬d.ªº¦C¤W«Ø¤@.¯Á¤Þ¡I
    
    ²Ä¤T¨B¡V¬d¬Ý¬O§_¦³.¶qªºparse.¶H
    ==============================
    select...
    
    |call|count|cpu|elapsed|disk|query|current|rows|
    |---------|-------|---------|---------|------|--------|---------|-------|
    |Parse|[M]2|[N]221|329|0|45|0|0|
    |Execute|[O]3|[P]9|17|0|0|0|0|
    |Fetch|3|6|8|0|[L]4|0|[K]1|
    -------------------------------------------------------------------------
    
    Missesinlibrarycacheduringparse:2[Q]
    
    [K]ªí©ú..¬d.¥uªð¦^¤@¦æ.Õu
    [L]ªí©ú§Ú.»Ý­nfetch4¦¸¤~¯à±o¨ì.Õu¡A.¬O¥¿±`ªº¡A¦].»Ý­n.¥~ªºfetch¾Þ§@¥H«K.
    ¬d¬O§_fetch¨ìcursorªº³Ì¦Z¡A.µM.¥i¯à¦³¨ä¥¦fetch..¡C
    
    
    [M]ªí©ú§Ú..¦æ¤F.¦¸parse(¥]§thardparseÉOsoftparse)¡V.¬O§Ú.¤£·Q¬Ý¨ìªº¡A
    ¯S.¬O.parse.¬q¾Þ§@¯Ó.cpu.·½¤ñexecute.¬q¯Ó.ªºcpu.·½([O]&;[P])
    ¦h±o¦h±o.­Ô¡C[Q]ªí©ú...parse¾Þ§@³£¬Ohardparse¡C¦pªG[Q]ªº­È.1¡A
    ....¥y¦³¤@.hardparse¡AµM¦Z¸ò.¤@.softparse(.....¦s¤¤±o¨ì
    ¤W¦¸¤ÀªRªº«H®§¡A¤ñhardparse­n°ª®Äªº¦h)¡C
    
    .¤W­±ªº¨Ò¤l..¡A.ªG¦}¤£¬O¯S.ªº§¥¡A¦]...¥y¥u.¦æ2¦¸¡AµM¦Ó¦pªG.¤_.Ác.
    ¦æªºsql..¡A¦pªG¤L¥G¨C¦¸.¦æ³£»Ý­nhardparse¡A..ªG´N..ªº«Ü§¥¡A¦¹.§Ú...
    .¥y¦³.¶qªºparse.¶H(excessiveparsing)¡C
    
    o¸Ñ....ªº¤èªk¡G
    -¨Ï¥Îbindvariables
    -¨Ïsharedpool¨¬.¤j¡A.¦Ó¦b.¦s¤¤®e.§A.¦æ.ªº¨C¤@..¥y¡A
    ¥H«K¤U¤@¦¸¥i¥H­«¥Î..¥y¡C¦ý.Ïú¤èªkªv.¤£ªv¥»¡A¦bÁc¦£ªº¨t.¤¤¦³..¤Þ°_
    ora-04031:unabletoallocate%sbytesofsharedmemory(%s,%s,%s)
    ..¡C
    -¨Ï¥Î8i·s¤Þ¤Jªº..cursor_sharing¡A«Ø.¦b....¦Z¦A¨Ï¥Î...¡A¦].¦³.
    ¨Ï¥Î...¦Z.¤Þ°_¨t.©Ê¯à¤U­°
    
    ¦p¦ó­°§Cparse.¬q¨Ï¥Îªºcpu..
    1.Rewritetheapplicationsostatementsdonotcontinuallyreparse.
    2.ReduceparsingbyusingtheinitializationparameterSESSION_CACHED_CURSORS.
    3.Usebindvariablestoreduceparsing.
    
    
    ª`·N¡G
    .¦í¦pªGcursor.¦³³Q..¡A.¦btkprofªº.¥X¤å¥ó¤¤¬Ý¤£¨ì¥ô¦ó.sqlªº.¥X¡C.¸m
    SQL_TRACE=false¦}¤£¯à..PL/SQLªºchildcursors¡A©Ò¥H­n¦b¦Û¤vªº¦s..µ{¤¤
    .¦¨¤Î....¦¡cursorªº..¡C¥O§Ú.°ª.ªº¬O¡A¦bSQL*Plus¤¤¡A.¥y¤@¥¹.¦æ§¹.¡A
    ..¥y..ªºcursor¤]¦Û...¤F¡C
    
    
    
    
    
    
    
    .¦Ò«H®§¡G
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