Re: pg_rewind in contrib

Hi,

On 2014/12/12 23:13, Heikki Linnakangas wrote:> Hi,>> I'd like to include pg_rewind in contrib. I originally wrote it
asan> external project so that I could quickly get it working with the> existing versions, and because I didn't feel it
wasquite ready for> production use yet. Now, with the WAL format changes in master, it is a> lot more maintainable than
before.Many bugs have been fixed since the> first prototypes, and I think it's fairly robust now.>> I propose that we
includepg_rewind in contrib/ now. Attached is a patch> for that. It just includes the latest sources from the current
pg_rewind>repository at https://github.com/vmware/pg_rewind. It is released under> the PostgreSQL license.>> For those
whoare not familiar with pg_rewind, it's a tool that allows> repurposing an old master server as a new standby server,
after>promotion, even if the old master was not shut down cleanly. That's a> very often requested feature.
 

I'm looking into pg_rewind with a very first scenario.
My scenario is here.

https://github.com/snaga/pg_rewind_test/blob/master/pg_rewind_test.sh

At least, I think a file descriptor "srcf" should be closed before
exiting copy_file_range(). I got "can't open file" error with
"too many open file" while running pg_rewind.

------------------------------------------------
diff --git a/contrib/pg_rewind/copy_fetch.c b/contrib/pg_rewind/copy_fetch.c
index bea1b09..5a8cc8e 100644
--- a/contrib/pg_rewind/copy_fetch.c
+++ b/contrib/pg_rewind/copy_fetch.c
@@ -280,6 +280,8 @@ copy_file_range(const char *path, off_t begin, off_t 
end, bool trunc)                write_file_range(buf, begin, readlen);                begin += readlen;        }
+
+       close(srcfd); }
 /*
------------------------------------------------

And I have one question here.

pg_rewind assumes that the source PostgreSQL has, at least, one 
checkpoint after getting promoted. I think the target timeline id
in the pg_control file to be read is only available after the first
checkpoint. Right?

Regards,

>
> - Heikki
>
>
>

-- 
NAGAYASU Satoshi <snaga@uptime.jp>