On 2025-03-29 Sa 12:17 PM, David G. Johnston wrote:
On Sat, Mar 29, 2025 at 9:06 AM Andrew Dunstan <and...@dunslane.net> wrote:


    On 2025-03-29 Sa 10:40 AM, David G. Johnston wrote:
    On Saturday, March 29, 2025, Kirill Reshke
    <reshkekir...@gmail.com> wrote:

        On Sat, 29 Mar 2025 at 09:47, jian he
        <jian.universal...@gmail.com> wrote:
        >
        > will use {table_beginscan, table_scan_getnextslot,
        table_endscan}
        > to output the data.
        > but views don't have storage, table_beginscan mechanism
        won't work.
        >
        > so i don't think this is possible for view.

        Well... So you are saying that let us have inconsistent features
        because of how things are implemented in core... I don't sure I'm
        buying that, but whatever, let's hear some other voices from the
        community. My argument is that while we are working on it,
        perhaps we
        should revise certain implementation specifics along the way.
        However,
        this is merely my opinion on the matter.


     At present copy {table} to only exists to support pg_dump.  It
    is not marketed as a general purpose export facility.


    *ahem*


    What is your evidence for that proposition? If this were true we
    would not support CSV mode, which pg_dump does not use. It might
    have limitations, but its use goes far beyond just pg_dump, both
    in theory and practice.




"copy {subquery} to" is a general-purpose exporter that makes use of those additional features.  Sure, they also work for the narrowed case of "copy {relation/table} to" but I make my claim on the very fact that {relation} cannot be stuff like foreign tables or partitioned tables, which pg_dump has no need to target.




I don't believe that the premise supports the conclusion.


cheers


andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com

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