From: | Ron <ronljohnsonjr(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: How to copy rows into same table efficiently |
Date: | 2021-10-26 09:05:53 |
Message-ID: | 982cf46b-c112-82cb-3f34-6904305761bb@gmail.com |
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Thread: | |
Lists: | pgsql-general |
On 10/26/21 1:04 AM, Arun Suresh wrote:
>
> Dear PG experts,
>
> We have a tenant discriminator column in our tables to enable storage of
> data from multiple
> tenants. This column is also part of the composite primary key.
> The customers may request creation of a tenant copy, which means if they
> currently have a
> tenant id "ABCD", they would like to copy all data "where tenant_id =
> 'ABCD'" to a new copy tenant "XYZ".
> The copy must also be done on the same table.
>
> Current approach taken is to build a query like below:
> INSERT INTO mytable (col1, col2, col3, col4) SELECT col1, 'XYZ', col3,
> col4 FROM mytable WHERE col2 = 'ABCD'
>
> Is there a better way to do this?
> There could be other tables with foreign key reference, would a simple
> ordering of the copy based on table relationship suffice?
That would be my first thought. Of course, FK dependencies quickly become a
rat's nest, so beware.
> Also if the table has millions of records, what are the things to take
> care of?
Take care of?
Anyway, for millions of rows, I might use COPY instead of INSERT (depending
on how many millions, how many indices, how large the rows, how fast the
machine, etc.
--
Angular momentum makes the world go 'round.
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