RE: Is table with b-tree index is still a heap table?

From: Chitale, Hemant K <Hemant-K.Chitale_at_sc.com>
Date: Wed, 2 Apr 2014 13:24:35 +0800
Message-ID: <0BDF2A25A09ADD40908745EEFC0A0FB6019F2D9D_at_HKJUMXMB103B.zone1.scb.net>

If a Primary Key isn't part of the design, I wouldn't "force-fit" one.  

In most applications 90-99% of the tables would be heap tables. IOTs are the rare exception.        

Hemant K Chitale    

From: Nik Tek [mailto:niktek2005_at_gmail.com] Sent: Wednesday, April 02, 2014 12:35 PM To: Chitale, Hemant K
Cc: ORACLE-L
Subject: Re: Is table with b-tree index is still a heap table?  

Thank you Hemant!  

Can you please elaborate a bit on 4).

Is it because d) doesn't provide any advantage?  

Is there an alternative in fixing the schema, in the current schema almost 40% of the tables are straight heap tables or heap+index.  

Thank you

Nik  

On Tue, Apr 1, 2014 at 8:21 PM, Chitale, Hemant K <Hemant-K.Chitale_at_sc.com> wrote:

1. Yes, a) is a heap table I know that, but b) is a heap table?

Yes, b) is a Heap Table PLUS an Index - the Table and Index are separate objects.    

2) Is there any advantage of bumping up the C1 column to PK, like storage, performance?

It depends. Does C1 not have a Unique Index definition yet ? You probably need to cleanup duplicates first. There is no storage benefit with a PK. A PK, in itself, doesn't offer a performance benefit if there's already an index. A PK is more about "clean" data and proper design.  

3) Is b) and c) are the same?

No. b) has a heap table and a separate index. c) is an IOT.  

4) Say my application is already out in the customers site, changing the C1 to PK would be tricky, instead can do solution d) ?

I wouldn't advise it.  

Hemant K Chitale    

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Nik Tek Sent: Wednesday, April 02, 2014 7:21 AM
To: oracle-l_at_freelists.org
Subject: Is table with b-tree index is still a heap table?  

Hi,  

I have question about oracle heap tables vs. tables with b-tree index vs. IOT tables.  

Say I have a table T1  

1. CREATE TABLE T1 (C1 NUMBER NOT NULL, C2 VARCHAR2(100));
2. CREATE TABLE T1 (C1 NUMBER NOT NULL, C2 VARCHAR2(100));

CREATE INDEX IDX_T1_C1 ON T1(C1);   c) CREATE TABLE T1 (C1 NUMBER NOT NULL, C2 VARCHAR2(100),

 CONSTRAINT PK_T1_C1 PRIMARY KEY (C1) ORGANIZATION INDEX);   d)  

CREATE SEQUENCE T1_SEQ INCREMENT BY 1;
/

ALTER TABLE T1 ADD SURR_KEY INTEGER NOT NULL;
/

ALTER TABLE T1 ADD CONSTRAINT PK_T1_C1_SK PRIMARY KEY (C1,SURR_KEY);
/

CREATE OR REPLACE TRIGGER T1_TRIG     BEFORE INSERT ON T1     FOR EACH ROW     BEGIN     SELECT T1_SEQ.nextval INTO :NEW.SURR_KEY FROM dual;

    END;     Questions:

1. Yes, a) is a heap table I know that, but b) is a heap table?
2. Is there any advantage of bumping up the C1 column to PK, like storage, performance?
3. Is b) and c) are the same?
4. Say my application is already out in the customers site, changing the C1 to PK would be tricky, instead can do solution d) ?

Thank you

Nik  

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Received on Wed Apr 02 2014 - 07:24:35 CEST