Re: What's the best practice to compare the transaction with the checkpoint?

On 7/6/2020 10:09 AM, Jialun Zhang wrote:

Thanks! But what I actually mean is how to do this in the backend source code. I think I could find a way to do this SELECT in backend.

What would be the advantage in that method?

Thank you,

Jialun Zhang

Laurenz Albe <laurenz.albe@cybertec.at> 于2020年7月6日周一 上午4:09写道：

On Sat, 2020-07-04 at 12:19 -0400, Jialun Zhang wrote:
> I am trying to add code to determine whether the transaction is checkpointed or not.
> So I think I need to compare the transaction ID with the checkpoint's and determine
> whether it is older or not. Could anyone tell me what's the best practice of doing
> this in Postgres? Is it done somewhere in the existing code?

You could use

   SELECT next_xid FROM pg_control_checkpoint();

to get information about the last checkpoint.

I refrain from asking what the point of the exercise is...

Yours,
Laurenz Albe
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Cybertec | https://www.cybertec-postgresql.com

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