Re: Column with NULLs, how would it impact an index
- From: David Fitzjarrell <oratune@xxxxxxxxx>
- To: "niktek2005@xxxxxxxxx" <niktek2005@xxxxxxxxx>, ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 10 Apr 2014 13:23:07 -0700 (PDT)
If it's not a bitmap index entirely NULL keys are not found in an index. I
blogged on a similar topic a while back:
http://dfitzjarrell.wordpress.com/2008/04/09/a-tale-of-two-indexes/
David Fitzjarrell
Primary author, "Oracle Exadata Survival Guide"
On Thursday, April 10, 2014 1:43 PM, Nik Tek <niktek2005@xxxxxxxxx> wrote:
Hi,
I have question on index in Oracle.
Say, I have a table T1
CREATE TABLE T1(C1 INT NOT NULL, C2 VARCHAR2(50) NULL, CONSTRAINT PK_T1_C1
PRIMARY KEY (C1));
CREATE INDEX IDX_T1_C2 ON T1(C2);
The column C2 accepts NULLS,
Question: Does this have any impact on the index?
The table could have millions of rows(15-20 million).
Can anyone send me some pointers on it, to read about indexes on null columns.
Thank you
Nik
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