RE: [PATCH] Reuse Workers and Replication Slots during Logical Replication

Dear Melih,

> > > Thanks for the 0003 patch. But it did not work for me. Can you create
> > > a subscription successfully with patch 0003 applied?
> > > I get the following error: " ERROR: table copy could not start
> > > transaction on publisher: another command is already in progress".
> >
> > You got the ERROR when all the patches (0001-0005) were applied, right?
> > I have focused on 0001 and 0002 only, so I missed something.
> > If it was not correct, please attach the logfile and test script what you did.
>
> Yes, I did get an error with all patches applied. But with only 0001
> and 0002, your version seems like working and mine does not.

Hmm, really? IIUC I did not modify 0001 and 0002 patches, I just re-assigned the
version number. I compared between yours and mine, but no meaningful differences
were found. E.g., following command compared v4-0002 and v16-0002:

```
diff --git a/../reuse_workers/v4-0002-Reuse-Tablesync-Workers.patch b/../reuse_workers/hayato/v16-0002-Reuse-Tablesync-Workers.patch
index 5350216e98..7785a573e4 100644
--- a/../reuse_workers/v4-0002-Reuse-Tablesync-Workers.patch
+++ b/../reuse_workers/hayato/v16-0002-Reuse-Tablesync-Workers.patch
@@ -1,7 +1,7 @@
-From d482022b40e0a5ce1b74fd0e320cb5b45da2f671 Mon Sep 17 00:00:00 2001
+From db3e8e2d7aadea79126c5816bce8b06dc82f33c2 Mon Sep 17 00:00:00 2001
From: Melih Mutlu <m(dot)melihmutlu(at)gmail(dot)com>
Date: Tue, 4 Jul 2023 22:04:46 +0300
-Subject: [PATCH 2/5] Reuse Tablesync Workers
+Subject: [PATCH v16 2/5] Reuse Tablesync Workers

This commit allows reusing tablesync workers for syncing more than one
table sequentially during their lifetime, instead of exiting after
@@ -324,5 +324,5 @@ index 7aba034774..1e9f8e6e72 100644
static inline bool
am_tablesync_worker(void)
--
-2.25.1
+2.27.0
```

For confirmation, please attach the logfile and test script what you did
if you could reproduce?

> What do you think about combining 0002 and 0003? Or should those stay
> separate?

I have no strong opinion, but it may be useful to keep them pluggable.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED