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Home > Forums > Programmers > DBMS Packages > Oracle: Oracle release 11g Forum

Use index to avoid full table scan

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cmmrfrds (Programmer)

17 May 12 10:52

Oracle 11.2 G

I am joining a table where I only need two fields the join key and one other field. If I created a concatenated index that contained the two fields would oracle determine that it can get all the needed information from the index and avoid a full table scan. The table has 71 million rows with an avg length of 307 bytes and takes 500K blocks. So, I would like to avoid the I/O necessary to read this table.

Thank you.

LKBrwnDBA (MIS)

17 May 12 12:54

Go for it! thumbsup2

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The person who says it can't be done should not interrupt the person doing it. -- Chinese proverb

sem (Programmer)

18 May 12 5:52

Oracle may utilize its INDEX FAST FULL SCAN method and read all fields directly from index not accessing table at all. But only in case your query uses only those 2 fields in index.

Regards, Dima
http://seminihin.narod.ru

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