| help calculating freelist groups [message #153297] |
Fri, 30 December 2005 20:31 |
mjschwenger
Messages: 137
Registered: July 2005
Location: US
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Senior Member |
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I know that the freelist groups are recommended mainly for RAC, but I have tried using multiple freelist groups in a single instance and it brings my throuput much higher. I have heavy insert application - avarage 300,000 inserts per minute.
This is a part of my statpack:
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~ % Total
Event Waits Time (s) Call Time
-------------------------------------------- ------------ ----------- ---------
db file sequential read 10,153,306 95,294 86.78
CPU time 7,538 6.86
db file parallel write 221,671 3,257 2.97
log file sync 173,262 1,747 1.59
log file parallel write 310,194 1,311 1.19
-------------------------------------------------------------
Initialy I tried with ASSM but the throuput was not goodand the concurency was extreamly high. Then I switched to Manual sement management and got worst results with single freelist setting. Then I increased the freelists to the number of the concurent user and had a huge insert improvement - almost 25% higher insert rate but not every time I was connecting - due to the process_id connecting the to freelist probably. I decided to try using a freelist groups and rebuild the tables and indexes with multiple freelist groups with single freelist. The throuput was even better then multiple freelists alone. But the tables/indexes are growing a lot and I have a lot of waisted space. (I also consider using higher pctfree factor of 50% to release the concurency) With over 70 mln rows per table - this is huge...
Please, help me calculate what will be the optimal freelist groups and freelists attached to them for good balance between space and high insert performance. There'll be space wasted but this is ok - the storage is not too expensive today...
Thanks a lot,mj
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