Re: Missing pg_control crashes postmaster

On July 23, 2018 12:31:13 PM PDT, Brian Faherty <anothergenericuser@gmail.com> wrote:
>Hey Hackers,
>
>If a postmaster is running and the pg_control file is removed postgres
>will PANIC.
>
>Steps to recreate:
>
>1.) start a new cluster
>2.) rm $DATADIR/pg_control
>3.) psql => CHECKPOINT;
>
>PANIC:  could not open control file "global/pg_control": No such file
>or directory
>
>After the PANIC there is no pg_control. Recovery would be difficult
>without a replica or a backup. Instead of crashing we can just write a
>new pg_control file since all the data is in memory at the time.
>
>There does not really seem to be a need for this behavior as all the
>information postgres needs is in memory at this point. I propose with
>a patch to just recreate pg_control on updates if it does not exist.

What's the issue this would solve? Given that there's moments, until the control file is rewritten, where you would be
toasteither way, I don't buy this gives much added safety. Nor have you explained which realistic scenarios lead to the
filemissing, without much broader problems being present. 


Andres
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