Re: [HACKERS] background sessions

On 12 December 2016 at 23:29, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Dec 12, 2016 at 10:02 AM, Craig Ringer
> <craig.ringer@2ndquadrant.com> wrote:
>> On 12 Dec. 2016 21:55, "Robert Haas" <robertmhaas@gmail.com> wrote:
>> On Sun, Dec 11, 2016 at 5:38 AM, Andrew Borodin <borodin@octonica.com>
>> wrote:
>>> 1. As far as I can see, we connot use COPY FROM STDIN in bg session?
>>> Since one of purposes is to orchestrate transactions, may be that
>>> would be valuable.
>>
>> A background worker has no client connection, so what would COPY FROM STDIN
>> do?
>>
>> It doesn't make sense. But a bgworker may well want to supply input to COPY.
>> A COPY FROM CALLBACK of COPY FROM FILEDESC or whatever.
>
> That's kinda weird, though.  I mean, you don't need to go through all
> of the COPY code just to call heap_multi_insert() or whatever, do you?
>  You can hand-roll whatever you need there.

And fire triggers and constraint checks if necessary, update indexes,
etc. But yeah.

The original idea with logical rep was to get COPY-format data from
the upstream when initializing a table, and apply it via COPY in a
bgworker. I think that's changed in favour of another approach in
logical rep now, but thought it was worth mentioning as something it
might make sense for someone to want to do.

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Remote DBA, Training
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