Re: pgsql: Refactor COPY FROM to use format callback functions.

On 2025-02-28 Fr 1:31 PM, Masahiko Sawada wrote:
> Refactor COPY FROM to use format callback functions.
>
> This commit introduces a new CopyFromRoutine struct, which is a set of
> callback routines to read tuples in a specific format. It also makes
> COPY FROM with the existing formats (text, CSV, and binary) utilize
> these format callbacks.
>
> This change is a preliminary step towards making the COPY FROM command
> extensible in terms of input formats.
>
> Similar to 2e4127b6d2d, this refactoring contributes to a performance
> improvement by reducing the number of "if" branches that need to be
> checked on a per-row basis when sending field representations in text
> or CSV mode. The performance benchmark results showed ~5% performance
> gain in text or CSV mode.
>
> Author: Sutou Kouhei<kou(at)clear-code(dot)com>
> Reviewed-by: Masahiko Sawada<sawada(dot)mshk(at)gmail(dot)com>
> Reviewed-by: Michael Paquier<michael(at)paquier(dot)xyz>
> Reviewed-by: Andres Freund<andres(at)anarazel(dot)de>
> Reviewed-by: Tomas Vondra<tomas(dot)vondra(at)enterprisedb(dot)com>
> Reviewed-by: Junwang Zhao<zhjwpku(at)gmail(dot)com>
> Discussion:https://postgr.es/m/20231204.153548.2126325458835528809.kou@clear-code.com

This patch has completely broken the file_textarray fdw, which uses
NextCopyFromRawFields(). Removing that from API is not a good thing.

cheers

andrew

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