Re: Composite primary key duplicate records - Issue In PostgreSQL But not in Oracle

> On Apr 22, 2020, at 10:09 AM, David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
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> On Wed, Apr 22, 2020 at 6:54 AM <soumik(dot)bhattacharjee(at)kpn(dot)com <mailto:soumik(dot)bhattacharjee(at)kpn(dot)com>> wrote:
> Hi Experts,
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> We are migrating Oracle to PostgreSQL and facing a challenge related to constrains.
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> In Oracle database there are lot of table consists of composite primary key which having duplicate records.
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> Example
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> Oracle table : --CONSTRAINT "TTT_PRX" PRIMARY KEY ("COL1", "COL2") – UNIQUE à Here in Oracle there is no issue
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> In PostgreSQL if I want to add the constraint post migration it throws error as duplicate record for COL1 (which is a number) as per business need, COL2 is date which is unique always.
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> alter table table_name add constraint ttt_prx unique(COL1, COL2);
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> COL1
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> COL2
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> Count
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> 102022194
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> 21-9-2019
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> 1
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> 102022194
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> 30-9-2019
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> 1
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> 102022194
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> 30-9-2019
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> 1
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> Is there a way to handle this in PostgreSQL?
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> If Oracle is telling you that having two records (102022194,30-9-2019) is not a violation of the defined unique constraint over those two columns it is wrong. PostgreSQL is handling this correctly.
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> Maybe you had a full-on timestamp in Oracle but in moving it to PostgreSQL you mis-typed it as a date so the difference in the time portion of the two records has been lost?
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> David J.

Correct, the issue is the data in Oracle. The date field internally stores down to the second; not a great idea to use date in as primary key on Oracle without truncating it first:

https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:47566188181366