ORACLE EXPLAIN PLANµÄ×ܽá
ÔÚORACLEÊý¾Ý¿âÖÐ,ÐèÒª¶ÔSQLÓï¾ä½øÐÐÓÅ»¯µÄ»°ÐèÒªÖªµÀÆäÖ´Ðмƻ®,´Ó¶øÕë¶ÔÐԵĽøÐе÷Õû.ORACLEµÄÖ´Ðмƻ®µÄ»ñµÃÓм¸ÖÖ·½·¨,ÏÂÃæ¾ÍÀ´×ܽáÏÂ
1¡¢EXPLAINµÄʹÓÃ
Oracle RDBMSÖ´ÐÐÿһÌõSQLÓï¾ä£¬¶¼±ØÐë¾¹ýOracleÓÅ»¯Æ÷µÄÆÀ¹À¡£ËùÒÔ£¬Á˽âÓÅ»¯Æ÷ÊÇÈçºÎÑ¡Ôñ(ËÑË÷)·¾¶ÒÔ¼°Ë÷ÒýÊÇÈçºÎ±»Ê¹Óõģ¬¶ÔÓÅ»¯SQLÓï¾äÓкܴóµÄ°ïÖú¡£Explain¿ÉÒÔÓÃÀ´Ñ¸ËÙ·½±ãµØ²é³ö¶ÔÓÚ¸ø¶¨SQLÓï¾äÖеIJéѯÊý¾ÝÊÇÈçºÎµÃµ½µÄ¼´ËÑË÷·¾¶(ÎÒÃÇͨ³£³ÆΪAccess Path)¡£´Ó¶øʹÎÒÃÇÑ¡Ôñ×îÓŵIJéѯ·½Ê½´ïµ½×î´óµÄÓÅ»¯Ð§¹û¡£
1.1 ¡¢°² ×°
ҪʹÓÃEXPLAINÊ×ÏÈÒªÖ´ÐÐÏàÓ¦µÄ½Å±¾£¬´´½¨³öExplain_plan±í¡£
¾ßÌå½Å±¾Ö´ÐÐÈçÏ£º
$ORACLE_HOME/rdbms/admin/utlxplan.sql (UNIX) ¸Ã½Å±¾ºó»áÉú³ÉÒ»¸ö±íÕâ¸ö³ÌÐò»á´´½¨Ò»¸öÃûΪplan_tableµÄ±í¡£
1.2 ¡¢Ê¹ÓÃ
³£¹æʹÓÃÓï·¨£º
explain PLAN [ SET STATEMENT_ID [=] < string literal > ] [ INTO < table_name > ]
FOR < sql_statement >
ÆäÖУº
STATEMENT_ID£ºÊÇÒ»¸öΨһµÄ×Ö·û´®£¬°Ñµ±Ç°Ö´Ðмƻ®Óë´æ´¢ÔÚͬһPLANÖеÄÆäËüÖ´Ðмƻ®Çø±ð¿ªÀ´¡£
TABLE_NAME£ºÊÇplan±íÃû£¬Ëü½á¹¹ÈçÇ°Ëùʾ£¬Äã¿ÉÒÔÈÎÒâÉ趨Õâ¸öÃû³Æ¡£
SQL_STATEMENT£ºÊÇÕæÕýµÄSQLÓï¾ä¡£
Ïà¹ØÎĵµ£º
oracle±í¿Õ¼ä²Ù×÷Ïê½â
1
2
3×÷Õߣº À´Ô´£º ¸üÐÂÈÕÆÚ£º2006-01-04
5
6
7½¨Á¢±í¿Õ¼ä
8
9CREATE TABLESPACE data01
10DATAFILE '/ora ......
ORACLE±¸·Ý²ßÂÔ(ORACLE BACKUP STRATEGY)
2007Äê11ÔÂ02ÈÕ ÐÇÆÚÎå 16:03
¸ÅÒª
1¡¢Á˽âʲôÊDZ¸·Ý
2¡¢Á˽ⱸ·ÝµÄÖØÒªÐÔ
3¡¢Àí½âÊý¾Ý¿âµÄÁ½ÖÖÔËÐз½Ê½
4¡¢Àí½â²»Í¬µÄ±¸·Ý·½Ê½¼°ÆäÇø±ð
5¡¢Á˽âÕýÈ·µÄ±¸·Ý²ßÂÔ¼°ÆäºÃ´¦
Ò»¡¢Á˽ⱸ·ÝµÄÖØÒªÐÔ
¿ÉÒÔ˵£¬´Ó¼ÆËã»úϵͳ³öÊÀµÄÄÇÌìÆ𣬾ÍÓÐÁ˱¸·ÝÕâ¸ö¸ÅÄ ......
Oracle Îï¼þµÄÃüÃûÏÞÖÆ
ÈκÎÎï¼þµÄÃû稱²»µÃ³¬過 30 λԪ(Bytes)
Oracle µÄ dummy query 寫·¨
SELECT SYSDATE from dual
Oracle 選È¡²¿·Ö資Áϵķ½·¨
SELECT * from table WHERE ROWNUM<10; /* È¡³öÇ° 10 筆 */
實現 Oracle ÉϵķÖ頁顯ʾ [¾«華] ......
Êý¾Ý¿âµÄÄÚ´æ½á¹¹£º
Memory structures are allocated to the Oracle instance when the instance is started.
The two major memory structures are known as the System Global Area(Also called the shared
Global Area)and the Program Global Area(also called the Private Global Area or the ......
¹ØÓÚ°²×°£º
°²×°Oracle10gʱ£¬ËùÊäÈëµÄÈ«¾ÖµÄSIDÃû³ÆΪtest(¼´Êý¾Ý¿âÃû£¬²»ÄÜ×÷ΪÓû§ÃûÀ´µÇ¼)£¬ÃÜÂëΪtest(¸ÃÃÜÂë¶ÔÓ¦µÄÓû§Îªsystem£¬sysµÈ)¡£
×°Íêºó£¬Èô´ÓÍøÒ³ÉϵǼoracle£¬ÔòÊäÈëurl£ºhttp://localhost:1158/em
ÈôÎÞ·¨ÏÔ ......