Re: POC PATCH: copy from ... exceptions to: (was Re: VLDB Features)

Hi, Danil and Nikita!
Thank you for reviewing.

Why is there no static keyword in the definition of the SafeCopying()
> function, but it is in the function declaration.
>
Correct this.

675: MemoryContext cxt =
> MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
> 676:
> 677: valid_row = NextCopyFrom(cstate, econtext, myslot->tts_values,
> myslot->tts_isnull);
> 678: tuple_is_valid = valid_row;
> 679:
> 680: if (valid_row)
> 681: sfcstate->safeBufferBytes += cstate->line_buf.len;
> 682:
> 683: CurrentMemoryContext = cxt;
>
> Why are you using a direct assignment to CurrentMemoryContext instead of
> using the MemoryContextSwitchTo function in the SafeCopying() routine?
>

"CurrentMemoryContext = cxt" is the same as "MemoryContextSwitchTo(cxt)",
you can see it in the implementation of MemoryContextSwitchTo(). Also
correct this.

When you initialize the cstate->sfcstate structure, you create a
> cstate->sfcstate->safe_cxt memory context that inherits from oldcontext.
> Was it intended to use cstate->copycontext as the parent context here?
>

Good remark, correct this.

Thanks Nikita Malakhov for advice to create file with errors. But I decided
to to log errors in the system logfile and don't print them to the
terminal. The error's output in logfile is rather simple - only error
context logs (maybe it's better to log all error information?).
There are 2 points why logging errors in logfile is better than logging
errors in another file (e.g. PGDATA/copy_ignore_errors.txt). The user is
used to looking for errors in logfile. Creating another file entails
problems like: 'what file name to create?', 'do we need to make file
rotation?', 'where does this file create?' (we can't create it in PGDATA
cause of memory constraints)

Regards,
Damir Belyalov
Postgres Professional