Subject: Re: WIP: System Versioned Temporal Table
To: Surafel Temesgen <surafel3000@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
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From: Vik Fearing <vik.fearing@2ndquadrant.com>
Message-ID: <b11fa573-38fa-ba57-96a9-e4dd9ce3fb76@2ndquadrant.com>
Date: Mon, 28 Oct 2019 16:36:09 +0100
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On 28/10/2019 13:48, Surafel Temesgen wrote:
>
>
> On Fri, Oct 25, 2019 at 10:45 PM Vik Fearing
> <vik.fearing@2ndquadrant.com <mailto:vik.fearing@2ndquadrant.com>> wrote:
>
>     >
>     >     I don't understand what you mean by this.
>     >
>     >
>     >
>     > The primary purpose of adding row end time to primary key is to
>     allow
>     > duplicate value to be inserted into a table with keeping
>     constraint in
>     > current data but it can be duplicated in history data. Adding row
>     > start time column to primary key will eliminate this uniqueness for
>     > current data which is not correct  
>
>
>     How?  The primary/unique keys must always be unique at every point
>     in time.
>
>
> From user prospect it is acceptable to delete and reinsert a record
> with the same key value multiple time which means there will be
> multiple record with the same key value in a history data but there is
> only one values in current data as a table without system versioning
> do .I add row end time column to primary key to allow user supplied
> primary key values to be duplicated in history data which is acceptable
>

Yes, I understand that.  I'm saying you should also add the row start
time column.