RE: Column with NULLs, how would it impact an index
Date: Fri, 11 Apr 2014 11:13:55 +0800
Message-ID: <0BDF2A25A09ADD40908745EEFC0A0FB601A8323A_at_HKMGAXMB103A.zone1.scb.net>
NULL values wouldn't be included in the index. So, the index would be "smaller" being only on non-NULL values.
What sort of queries would you be running ? Queries for C2 IS NULL would be out of luck, doing a Full Table Scan.
Hemant K Chitale
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Nik Tek
Sent: Friday, April 11, 2014 3:42 AM
To: ORACLE-L
Subject: Column with NULLs, how would it impact an index
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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-- http://www.freelists.org/webpage/oracle-lReceived on Fri Apr 11 2014 - 05:13:55 CEST