Re: log_min_messages per backend type

On Thu, Jul 31, 2025 at 11:19:48AM -0300, Euler Taveira wrote:
> On Thu, Mar 6, 2025, at 10:33 AM, Andres Freund wrote:
> > Huh, the startup process is among the most crucial things to monitor?
> >
> 
> Good point. Fixed.
> 
> After collecting some suggestions, I'm attaching a new patch contains the
> following changes:
> 
> - patch was rebased
> - include Alvaro's patch (v2-0001) [1] as a basis for this patch
> - add ioworker as new backend type
> - add startup as new backend type per Andres suggestion
> - small changes into documentation
> 
> > I don't know what I think about the whole patch, but I do want to voice
> > *strong* opposition to duplicating a list of all backend types into multiple
> > places. It's already painfull enough to add a new backend type, without having
> > to pointlessly go around and manually add a new backend type to mulltiple
> > arrays that have completely predictable content.
> >
> 
> I'm including Alvaro's patch as is just to make the CF bot happy and to
> illustrate how it would be if we adopt his solution to centralize the list of
> backend types. I think Alvaro's proposal overcomes the objection [2], right?
> 

I think we can avoid memory allocation by using pg_strncasecmp().

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 5c769dd7bcc..f854b2fac93 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -1343,14 +1343,10 @@ check_log_min_messages(char **newval, void **extra, GucSource source)
         }
         else
         {
-            char       *loglevel;
-            char       *btype;
-            bool        found = false;

-            btype = palloc((sep - tok) + 1);
-            memcpy(btype, tok, sep - tok);
-            btype[sep - tok] = '\0';
-            loglevel = pstrdup(sep + 1);
+            char       *btype = tok;
+            char       *loglevel = sep + 1;
+            bool        found = false;

             /* Is the log level valid? */
             for (entry = server_message_level_options; entry && entry->name; entry++)
@@ -1377,7 +1373,7 @@ check_log_min_messages(char **newval, void **extra, GucSource source)
             found = false;
             for (int i = 0; i < BACKEND_NUM_TYPES; i++)
             {
-                if (pg_strcasecmp(log_min_messages_backend_types[i], btype) == 0)
+                if (pg_strncasecmp(log_min_messages_backend_types[i], btype, sep - tok) == 0)
                 {
                     /* Reject duplicates for a backend type. */
                     if (assigned[i])

-- 
Best regards,
Japin Li
ChengDu WenWu Information Technology Co., LTD.