Re: Force lookahead in COPY FROM parsing

On Thu, Mar 4, 2021 at 5:13 AM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>
> I posted this earlier at
>
https://www.postgresql.org/message-id/9ec25819-0a8a-d51a-17dc-4150bb3cca3b@iki.fi
,
> and that led to removing FE/BE protocol version 2 support. That's been
> committed now, so here's COPY FROM patch again, rebased.

Looks good to me. Just a couple minor things:

+ * Look at the next character. If we're at EOF, c2 will wind
+ * up as '\0' because of the guaranteed pad of raw_buf.
*/
- IF_NEED_REFILL_AND_NOT_EOF_CONTINUE(0);
-
- /* get next char */
c = copy_raw_buf[raw_buf_ptr];

The new comment seems copy-pasted from the c2 statements further down.

- if (raw_buf_ptr >= copy_buf_len || need_data)
+#define COPY_READ_LINE_LOOKAHEAD 4
+ if (raw_buf_ptr + COPY_READ_LINE_LOOKAHEAD >= copy_buf_len)

Is this #define deliberately put down here rather than at the top of the
file?

- * of the buffer and then we load more data after that. This case occurs
only
- * when a multibyte character crosses a bufferload boundary.
+ * of the buffer and then we load more data after that.

Is the removed comment really invalidated by this patch? I figured it was
something not affected until the patch to do the encoding conversion in
larger chunks.

--
John Naylor
EDB: http://www.enterprisedb.com