Re: Best Approach for Swapping a Table with its Copy

On 2/12/25 1:27 PM, Marcelo Fernandes wrote:
> On Thu, Feb 13, 2025 at 10:02 AM Adrian Klaver

> This is a simplified version of the original table:
> 
> CREATE TABLE bookings (
>      id SERIAL PRIMARY KEY,
>      resource_id INT NOT NULL,
>      start_date DATE NOT NULL,
>      end_date DATE NOT NULL
> );
> 
>> 3) The exclusion constraint definition.
> 
> The copy table would have an exclusion constraint such as:
> 
> ALTER TABLE bookings
> ADD CONSTRAINT no_date_overlap_for_resource_id
> EXCLUDE USING gist (
>      resource_id WITH =,
>      daterange(start_date, end_date, '[]') WITH &&
> );

Do you know this will not fail on the existing data?

> 
>> 4) Definition of what 'fairly large' is.
> 
> This table is over 400GB

Do you have room for a complete copy of the table?


> 
> This is done to avoid having to hold an exclusive lock for a long amount of
> time, thus creating application outages.

I am not seeing how this can be done without some outage for that table.

What sort of time frame is acceptable?

> 
> Hope that clarifies the situation a bit better
>    - Marcelo

-- 
Adrian Klaver
adrian.klaver@aklaver.com