RE: [POC] Fast COPY FROM command for the table with foreign partitions

Hi

> see new version in attachment.

I took a look into the patch, and have some comments.

1.
+ PG_FINALLY();
+ {
+ copy_fmstate = NULL; /* Detect problems */
I don't quite understand this comment,
does it means we want to detect something like Null reference ?

2.
+ PG_FINALLY();
+ {
...
+ if (!OK)
+ PG_RE_THROW();
+ }
Is this PG_RE_THROW() necessary ?
IMO, PG_FINALLY will reproduce the PG_RE_THROW action if we get to the code block due to an error being thrown.

3.
+ ereport(ERROR,
+ (errmsg("unexpected extra results during COPY of table: %s",
+ PQerrorMessage(conn))));

I found some similar message like the following:

pg_log_warning("unexpected extra results during COPY of table \"%s\"",
tocEntryTag);
How about using existing messages style ?

4.
I noticed some not standard code comment[1].
I think it's better to comment like:
/*
* line 1
* line 2
*/

[1]-----------
+ /* Finish COPY IN protocol. It is needed to do after successful copy or
+ * after an error.
+ */

+/*
+ *
+ * postgresExecForeignCopy

+/*
+ *
+ * postgresBeginForeignCopy

-----------
Best regards,
Houzj