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

Hi, Andres!

Thank you for reviewing.

> I don't think this is the right approach. Creating a subtransaction for
> each row will cause substantial performance issues.
>

Subtransactions aren't created for each row. The block of rows in one
subtransaction is 1000 (SAFE_BUFFER_SIZE) and can be changed. There is also
a constraint for the number of bytes MAX_SAFE_BUFFER_BYTES in safe_buffer:
while (sfcstate->saved_tuples < SAFE_BUFFER_SIZE &&
sfcstate->safeBufferBytes < MAX_SAFE_BUFFER_BYTES)

We now can call data type input functions without throwing errors, see
> InputFunctionCallSafe(). Use that to avoid throwing an error instead of
> catching it.
>
InputFunctionCallSafe() is good for detecting errors from input-functions
but there are such errors from NextCopyFrom () that can not be detected
with InputFunctionCallSafe(), e.g. "wrong number of columns in row''. Do
you offer to process input-function errors separately from other errors?
Now all errors are processed in one "switch" loop in PG_CATCH, so this
change can complicate code.

Regards,
Damir Belyalov
Postgres Professional