Dear Sawada-san,
> I think it's a good idea to support it at least on HEAD. I've attached
> a patch for that.
+1. I've confirmed that pg_rewind and -R can't output dbname for now,
and your patch allows to do it.
Few comments for your patch.
1.
pg_basebackup.sgml has below description. I feel this can be ported to
pg_rewind.sgml as well.
```
The dbname will be recorded only if the dbname was
specified explicitly in the connection string or <link linkend="libpq-envars">
environment variable</link>.
```
2.
I'm not sure whether recovery_gen.h/c is a correct place for the exported function
GetDbnameFromConnectionOptions(). The function itself does not handle
postgresql.cuto.conf file.
I seeked other header files and felt that connect_utils.h might be.
```
/*-------------------------------------------------------------------------
*
* Facilities for frontend code to connect to and disconnect from databases.
```
Another idea is to change the third API to accept the whole connection string, and
it extracts dbname from it. In this approach we can make GetDbnameFromConnectionOptions()
to static function - which does not feel strange for me.
Best regards,
Hayato Kuroda
FUJITSU LIMITED
