Re: Call EndCopyFrom() after initial table sync in logical replication

> On May 8, 2026, at 12:21, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>
> On Fri, May 8, 2026 at 11:34 AM cca5507 <cca5507(at)qq(dot)com> wrote:
>>
>> Hi,
>>
>> Maybe we want to add "free_parsestate(pstate);" after the "EndCopyFrom()" as well?
>
> What actual issue could occur if free_parsestate() is not called there?
>
> Since pstate->p_target_relation does not seem to be used afterward,
> omitting free_parsestate() appears mostly harmless to me. Bascailly
> calling free_parsestate() after make_parsestate() seems intuitive,
> but from a quick grep I found several places that call make_parsestate()
> without a corresponding free_parsestate().
>
> Regards,
>
> --
> Fujii Masao

I don’t think this is a serious leak. In this path, pstate and attnamelist are allocated in CurTransactionContext, and the transaction is committed immediately after copy_table() finishes, so that memory is reclaimed at transaction end. Explicitly freeing them would be mostly for code readability, not to fix a memory leak. So, I am okay to not free them.

While tracing the code, I noticed another issue that is probably more worth addressing. copy_table() currently does:
```
copybuf = makeStringInfo();
```

But copybuf is only used by copy_read_data(), and there it's really just acting as a small state holder for data, len, and cursor, rather than as a normal growable StringInfo. That means we do not need to allocate a StringInfo object or its backing buffer at all.

It would be cleaner to use a plain StringInfoData and simply reinitialize or zero it in copy_table(). See the attached diff for the proposed change.

David Rowley has made several cleanup changes in this area to prefer stack-allocated StringInfoData, for example a63bbc811d41b3567eb37fe2636e660a852dbbf2. This change seems consistent with that direction.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/