Optimal One Pass Multi Pass
PGA_SIZE Executions Executions Executions
-------------------------------------------------------
8kb <= PGA < 16kb 60725456 0 0
16kb <= PGA < 32kb 128742 0 0
32kb <= PGA < 64kb 55579 0 0
64kb <= PGA < 128kb 36622 0 0
128kb <= PGA < 256kb 31909 0 0
256kb <= PGA < 512kb 756 0 0
512kb <= PGA < 1024kb 402 33 0
1mb <= PGA < 2mb 76 24454 0
2mb <= PGA < 4mb 4716 835 0
4mb <= PGA < 8mb 734 723 20
8mb <= PGA < 16mb 37 0 160
16mb <= PGA < 32mb 0 2 64
32mb <= PGA < 64mb 0 0 32 13 rows selected. What we can see here is that the larger the requested workarea size - the more
frequently we resorted to using the disk - in fact for sorts/hashes that
consumed more than 16mb of RAM, we resorted to disk each time. This would be an
indication that our PGA aggregate target was insufficient (the 24,454 one pass
executions for sorts beween 1 to 2m of RAM really indicates that). In this case
- the tables didn't lie, I had the PGA aggregate target set to 25meg initially
and by correcting the problem and setting it to 250m and later 432m - the disk
usaged dropped off considerably (well, all together). 这里为什么说1 to 2m of ram真正的表明了pga是不足的???
请求各位高人
PGA_SIZE Executions Executions Executions
-------------------------------------------------------
8kb <= PGA < 16kb 60725456 0 0
16kb <= PGA < 32kb 128742 0 0
32kb <= PGA < 64kb 55579 0 0
64kb <= PGA < 128kb 36622 0 0
128kb <= PGA < 256kb 31909 0 0
256kb <= PGA < 512kb 756 0 0
512kb <= PGA < 1024kb 402 33 0
1mb <= PGA < 2mb 76 24454 0
2mb <= PGA < 4mb 4716 835 0
4mb <= PGA < 8mb 734 723 20
8mb <= PGA < 16mb 37 0 160
16mb <= PGA < 32mb 0 2 64
32mb <= PGA < 64mb 0 0 32 13 rows selected. What we can see here is that the larger the requested workarea size - the more
frequently we resorted to using the disk - in fact for sorts/hashes that
consumed more than 16mb of RAM, we resorted to disk each time. This would be an
indication that our PGA aggregate target was insufficient (the 24,454 one pass
executions for sorts beween 1 to 2m of RAM really indicates that). In this case
- the tables didn't lie, I had the PGA aggregate target set to 25meg initially
and by correcting the problem and setting it to 250m and later 432m - the disk
usaged dropped off considerably (well, all together). 这里为什么说1 to 2m of ram真正的表明了pga是不足的???
请求各位高人
解决方案 »
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2mb <= PGA < 4mb 4716 835 0 很明显呀
1M-2M的时候ONE PASS为24454
而只要增大到2-4M ONE PASS就锐减到835次