Re: Improvements in Copy From

Hi Vignesh

On Wed, Jul 1, 2020 at 3:46 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:

> Hi,
>
> While reviewing copy from I identified few improvements for copy from
> that can be done :
> a) copy from stdin copies lesser amount of data to buffer even though
> space is available in buffer because minread was passed as 1 to
> CopyGetData, Hence it only reads until the data read from libpq is
> less than minread. This can be fixed by passing the actual space
> available in buffer, this reduces the unnecessary frequent calls to
> CopyGetData.
>

why not applying the same optimization on file read ?

> c) Copy from reads header line and do nothing for the header line, we
> need not clear EOL & need not convert to server encoding for the
> header line.
>

We have a patch for column matching feature [1] that may need a header line
to be further processed. Even without that I think it is preferable to
process the header line for nothing than adding those checks to the loop,
performance-wise.

[1].
https://www.postgresql.org/message-id/flat/CAF1-J-0PtCWMeLtswwGV2M70U26n4g33gpe1rcKQqe6wVQDrFA(at)mail(dot)gmail(dot)com

regards

Surafel