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0°ÇÀÇ Èı⺸±âÇؽÃÁ¶Àνà Build Input°ú Probe InputÀ» ½º¿ÍÇÎ ÇÏ´Â ÈùÆ®¿¡ ´ëÇØ ±â¼úÇÑ ¸®Æ÷Æ® Âü°íÀÚ·áÀÔ´Ï´Ù.
swap join inputs, no swap join inputs
ÇؽÃÁ¶ÀÎÀº input swapping(build input°ú probed inputÀ» ¹Ù²Ù±â)À» Áö¿øÇÑ´Ù.
¿ÜºÎÁ¶ÀÎ(outer join)ÀÇ °æ¿ì µå¶óÀ̺ù Å×À̺íÀÌ ÀÌ¹Ì Á¤ÇØÁ® ÀÖ´Ù.from t1, t2 where t1.col1()t2.col1-> Á¶Àμø¼´Â t2-> t1, t2µå¶óÀ̺ù from t1, t2 where t1.col1t2.col1()-> Á¶Àμø¼´Â t1-> t2, t1µå¶óÀ̺ù
swap join inputs, no swap join inputs
ÇؽÃÁ¶Àο¡¼ Á¶Àμø¼°¡ À§¿Í °°´Ù°í ÇÏ´õ¶óµµ ½ÇÁ¦ ½ÇÇàÀ» Çغ¸¸é ¿À¶óŬ ¿ÉƼ¸¶ÀÌÀú´Â Å«Å×À̺íÀÌ µå¶óÀ̺ù(driving, build inout)À̶ó¸é À̸¦ ÇÇÇÏ°í ÀÛÀº Å×À̺íÀÌ µå¶óÀ̺ùÀÌ µÇµµ·Ï ÇÑ´Ù.
hash outer join, hash semi join, hash anti joinÀÌ ¼öÇàµÇ´Â °æ¿ì µå¶óÀ̺ù
Å×À̺í(build input)À» ½º¿ÍÇÎ ÇÒ ¼ö ÀÖ´Ù.
swap join inputs(Å×À̺í¸í) : ±â¼úÇÑ Å×À̺íÀ» build inputÀ¸·Î ½º¿ÍÇÎ Ç϶ó ´Â ÀǹÌ.
no swap join inputs(Å×À̺í¸í) : ±â¼úÇÑ Å×ÀÌºí¿¡ ´ëÇØ ½º¿ÍÇÎÀ» ºñÈ°¼ºÈ
ÇÑ´Ù.
½Ç½À-1
½Ç½Àȯ°æ ¿À¶óŬ11g r2, myemp1Àº 1 ¸¸°Ç, mydept1Àº 7°Ç
¿ÉƼ¸¶ÀÌÀú ¸ðµå´Â optimizer mode all rows, cbo
select * from myemp1; select * from mydept1; show parameter optimizer mode
ordered·Î ÀÎÇØ Á¶ÀιæÇâÀÌ myemp1-> mydept1, Áï myemp1ÀÌ µå¶óÀ̺ù
7ÃÊ, myemp1ÀÌ build input(driving)
select /* ordered use hash(d) */ * from myemp1 e, mydept1 d
where e.deptno d.deptno ; ½Ç½À-2
swap join inputs ÈùÆ®¸¦ ÀÌ¿ëÇؼ µå¶óÀ̺ùÀ» ½º¿ÍÇÎÇ϶ó°í Áö½Ã
ordered use hash(d) ÈùÆ®·Î º¼¶§ ¿ø·¡ µå¶óÀ̺ùÀº myemp1ÀÌ´Ù.
0ÃÊ, mydept1ÀÌ build input(driving)
select /* ordered use hash(d) swap join inputs(d) */ * from myemp1 e, mydept1 d where e.deptno d.deptno;
myemp1À» build inputÀ¸·Î ½º¿ÍÇÎ Ç϶ó´Â ÈùÆ®´Â ÀÛµ¿µÇÁö ¾Ê´Â´Ù.
¿À¶óŬÀÌ ±âº»ÀûÀ¸·Î ÀÛÀº Å×À̺íÀ» build inputÀ» Çϱ⠶§¹®ÀÌ´Ù
mydept1ÀÌ build input(driving)
select /* swap join inputs(e) */ * from myemp1 e , mydept1 d
where e.deptno d.deptno ; ½Ç½À-3
outer joinÀÎ °æ¿ì ÀÖ´ÂÂÊ Å×À̺íÀÌ ÀÎÀÚ·Î µé¾î¿À¸é ½º¿ÍÇÎ ÇÑ´Ù.
myemp1ÀÌ µå¶óÀ̺ù
select /* swap join inputs(e) */ * from myemp1 e , mydept1 d (ÀÌÇÏ »ý·«)
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¹®¼°øÀ¯ ÀڷḦ µî·ÏÇØ ÁÖ¼¼¿ä.
¹®¼°øÀ¯ Æ÷ÀÎÆ®¿Í Çö±ÝÀ» µå¸³´Ï´Ù.
Æ÷ÀÎÆ® : ÀÚ·á 1°Ç´ç ÃÖ´ë 5,000P Áö±Þ
Çö±Ý : ÀÚ·á 1°Ç´ç ÃÖ´ë 2,000¿ø Áö±Þ