RE: Index Range Scan vs Fast full scan

No, I don't think it's a waste of time. An FFS should be faster, if you're going to read the entire index. FFS does multi-block reads, where the range scan will do single-block reads and walk through the index structures.

What hint are you using? INDEX_FFS? How complex is the SQL? Can you post it along w/ execution plan?

-Mark

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Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning

There is nothing so useless as doing efficiently that which shouldn't be done at all. -Peter F. Drucker, 1909-2005

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ken Naim Sent: Wednesday, January 10, 2007 5:17 PM To: oracle-l_at_freelists.org
Subject: Index Range Scan vs Fast full scan

From a perfromence point of view is a fast full scan (ffs) of an index faster than a index range scan when they both read the index fully? I am trying to test this but i having diffiuclty to get my plan to use a ffs even when hinted.

Context:
My btree index has only 2 values N and P and i dont use a bitmap as i can't rebuild after every load as the table has 225M rows in it. the index only has 7M rows as the rest of the values are null and a particular query needs to access all 7m rows that the index refers to. So both the ffs and the range scan read the same data. My question is am I wasting my time trying to get the plan to do a ffs of the index?
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http://www.freelists.org/webpage/oracle-l Received on Wed Jan 10 2007 - 16:21:54 CST