Re: %d in log_line_prefix doesn't work for bg/autovacuum workers

Hi,

On 2014-05-16 19:54:56 +0200, Andres Freund wrote:
> Hi,
>
> elog.c's log_line_prefix() processes %d with:
>             case 'd':
>                 if (MyProcPort)
>                 {
>                     const char *dbname = MyProcPort->database_name;
>
>                     if (dbname == NULL || *dbname == '\0')
>                         dbname = _("[unknown]");
>                     if (padding != 0)
>                         appendStringInfo(buf, "%*s", padding, dbname);
>                     else
>                         appendStringInfoString(buf, dbname);
>                 }
>                 else if (padding != 0)
>                     appendStringInfoSpaces(buf,
>                                            padding > 0 ? padding : -padding);
> write_csvlog() uses similar logic.
>
> Unfortunately MyProcPort only exists in user initiated backends.
>
> It's imo pretty annoying that neither bgworkers nor autovacuum workers
> show the proper database in the log. Why don't we just populate a global
> variable in InitPostgres() once we're sure which database the backend is
> connected to? We could fill fake MyProcPorts, but that doesn't seem like
> a good idea to me.

The attached simple patch implements the former idea.

We could probably replace a couple of get_database_name(MyDatabaseId)
calls by it, but that doesn't look that important.

Greetings,

Andres Freund

--
 Andres Freund                       http://www.2ndQuadrant.com/
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