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Re: v18 virtual columns
2+ messages / 2 participants
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* Re: v18 virtual columns
@ 2025-02-20 14:30  Ron Johnson <[email protected]>
  0 siblings, 1 reply; 2+ messages in thread

From: Ron Johnson @ 2025-02-20 14:30 UTC (permalink / raw)
  To: pgsql-generallists.postgresql.org <[email protected]>

On Thu, Feb 20, 2025 at 8:07 AM Dominique Devienne <[email protected]>
wrote:

> Hi. I've just read
> https://www.dbi-services.com/blog/postgresql-18-virtual-generated-columns/
>
> and I'm wondering whether there will be a way to ALTER existing STORED
> generated columns, to be virtual? W/o rewriting the whole table that is.
>

What about dropping the existing stored column then adding the new virtual
column?

You won't get any disk space saving for existing records, but it's not
going to rewrite the table.

-- 
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!


^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: v18 virtual columns
@ 2025-02-20 14:33  Dominique Devienne <[email protected]>
  parent: Ron Johnson <[email protected]>
  0 siblings, 0 replies; 2+ messages in thread

From: Dominique Devienne @ 2025-02-20 14:33 UTC (permalink / raw)
  To: Ron Johnson <[email protected]>; +Cc: pgsql-generallists.postgresql.org <[email protected]>

On Thu, Feb 20, 2025 at 3:31 PM Ron Johnson <[email protected]> wrote:

> On Thu, Feb 20, 2025 at 8:07 AM Dominique Devienne <[email protected]>
> wrote:
>
>> Hi. I've just read
>> https://www.dbi-services.com/blog/postgresql-18-virtual-generated-columns/
>>
>> and I'm wondering whether there will be a way to ALTER existing STORED
>> generated columns, to be virtual? W/o rewriting the whole table that is.
>>
>
> What about dropping the existing stored column then adding the new virtual
> column?
>
> You won't get any disk space saving for existing records, but it's not
> going to rewrite the table.
>

Didn't think of that, but yes, I think that would work.
They are GENERATED columns, so the values stored are derived data anyway,
indeed.

I also didn't know DROP COLUMN was smart enough not rewriting the column,
that's good.

Thanks, --DD


^ permalink  raw  reply  [nested|flat] 2+ messages in thread

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2025-02-20 14:30 Re: v18 virtual columns Ron Johnson <[email protected]>
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