Disallow setting client_min_messages higher than ERROR.

Previously it was possible to set client_min_messages to FATAL or PANIC,
which had the effect of suppressing transmission of regular ERROR messages
to the client.  Perhaps that seemed like a useful option in the past, but
the trouble with it is that it breaks guarantees that are explicitly made
in our FE/BE protocol spec about how a query cycle can end.  While libpq
and psql manage to cope with the omission, that's mostly because they
are not very bright; client libraries that have more semantic knowledge
are likely to get confused.  Notably, pgODBC doesn't behave very sanely.
Let's fix this by getting rid of the ability to set client_min_messages
above ERROR.

In HEAD, just remove the FATAL and PANIC options from the set of allowed
enum values for client_min_messages.  (This change also affects
trace_recovery_messages, but that's OK since these aren't useful values
for that variable either.)

In the back branches, there was concern that rejecting these values might
break applications that are explicitly setting things that way.  I'm
pretty skeptical of that argument, but accommodate it by accepting these
values and then internally setting the variable to ERROR anyway.

In all branches, this allows a couple of tiny simplifications in the
logic in elog.c, so do that.

Also respond to the point that was made that client_min_messages has
exactly nothing to do with the server's logging behavior, and therefore
does not belong in the "When To Log" subsection of the documentation.
The "Statement Behavior" subsection is a better match, so move it there.

Jonah Harris and Tom Lane

Discussion: https://postgr.es/m/7809.1541521180@sss.pgh.pa.us
Discussion: https://postgr.es/m/15479-ef0f4cc2fd995ca2@postgresql.org

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index b8e32d765bd1f70d767c278cbdde83ab3b8569f5..567d2246e824691672a35da25a19d6131af73681 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -5111,28 +5111,6 @@ local0.*    /var/log/postgresql
 
      <variablelist>
 
-     <varlistentry id="guc-client-min-messages" xreflabel="client_min_messages">
-      <term><varname>client_min_messages</varname> (<type>enum</type>)
-      <indexterm>
-       <primary><varname>client_min_messages</varname> configuration parameter</primary>
-      </indexterm>
-      </term>
-      <listitem>
-       <para>
-        Controls which message levels are sent to the client.
-        Valid values are <literal>DEBUG5</literal>,
-        <literal>DEBUG4</literal>, <literal>DEBUG3</literal>, <literal>DEBUG2</literal>,
-        <literal>DEBUG1</literal>, <literal>LOG</literal>, <literal>NOTICE</literal>,
-        <literal>WARNING</literal>, <literal>ERROR</literal>, <literal>FATAL</literal>,
-        and <literal>PANIC</literal>.  Each level
-        includes all the levels that follow it.  The later the level,
-        the fewer messages are sent.  The default is
-        <literal>NOTICE</literal>.  Note that <literal>LOG</literal> has a different
-        rank here than in <varname>log_min_messages</varname>.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry id="guc-log-min-messages" xreflabel="log_min_messages">
       <term><varname>log_min_messages</varname> (<type>enum</type>)
       <indexterm>
@@ -5150,7 +5128,7 @@ local0.*    /var/log/postgresql
         follow it.  The later the level, the fewer messages are sent
         to the log.  The default is <literal>WARNING</literal>.  Note that
         <literal>LOG</literal> has a different rank here than in
-        <varname>client_min_messages</varname>.
+        <xref linkend="guc-client-min-messages"/>.
         Only superusers can change this setting.
        </para>
       </listitem>
@@ -6471,6 +6449,27 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
      <title>Statement Behavior</title>
      <variablelist>
 
+     <varlistentry id="guc-client-min-messages" xreflabel="client_min_messages">
+      <term><varname>client_min_messages</varname> (<type>enum</type>)
+      <indexterm>
+       <primary><varname>client_min_messages</varname> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        Controls which message levels are sent to the client.
+        Valid values are <literal>DEBUG5</literal>,
+        <literal>DEBUG4</literal>, <literal>DEBUG3</literal>, <literal>DEBUG2</literal>,
+        <literal>DEBUG1</literal>, <literal>LOG</literal>, <literal>NOTICE</literal>,
+        <literal>WARNING</literal>, and <literal>ERROR</literal>.
+        Each level includes all the levels that follow it.  The later the level,
+        the fewer messages are sent.  The default is
+        <literal>NOTICE</literal>.  Note that <literal>LOG</literal> has a different
+        rank here than in <xref linkend="guc-log-min-messages"/>.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-search-path" xreflabel="search_path">
       <term><varname>search_path</varname> (<type>string</type>)
       <indexterm>

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index b9c11301ca23f4bfb7a3c1d15091c621b0087829..ca02aac4ebddc9876bfa9c24483ca3b24fe21aa3 100644 (file)
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -469,9 +469,7 @@ errfinish(int dummy,...)
         * progress, so that we can report the message before dying.  (Without
         * this, pq_putmessage will refuse to send the message at all, which is
         * what we want for NOTICE messages, but not for fatal exits.) This hack
-        * is necessary because of poor design of old-style copy protocol.  Note
-        * we must do this even if client is fool enough to have set
-        * client_min_messages above FATAL, so don't look at output_to_client.
+        * is necessary because of poor design of old-style copy protocol.
         */
        if (elevel >= FATAL && whereToSendOutput == DestRemote)
                pq_endcopyout(true);
@@ -1747,12 +1745,7 @@ pg_re_throw(void)
                else
                        edata->output_to_server = (FATAL >= log_min_messages);
                if (whereToSendOutput == DestRemote)
-               {
-                       if (ClientAuthInProgress)
-                               edata->output_to_client = true;
-                       else
-                               edata->output_to_client = (FATAL >= client_min_messages);
-               }
+                       edata->output_to_client = true;
 
                /*
                 * We can use errfinish() for the rest, but we don't want it to call

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ce54828fbb8fb7d7d512ba46c2cd5255ba1c79ae..0327b295da8f3cdab135434df8ff85fc8b72df1b 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -215,7 +215,8 @@ static const struct config_enum_entry bytea_output_options[] = {
 
 /*
  * We have different sets for client and server message level options because
- * they sort slightly different (see "log" level)
+ * they sort slightly different (see "log" level), and because "fatal"/"panic"
+ * aren't sensible for client_min_messages.
  */
 static const struct config_enum_entry client_message_level_options[] = {
        {"debug5", DEBUG5, false},
@@ -229,8 +230,6 @@ static const struct config_enum_entry client_message_level_options[] = {
        {"notice", NOTICE, false},
        {"warning", WARNING, false},
        {"error", ERROR, false},
-       {"fatal", FATAL, true},
-       {"panic", PANIC, true},
        {NULL, 0, false}
 };
 
@@ -3924,7 +3923,7 @@ static struct config_enum ConfigureNamesEnum[] =
        },
 
        {
-               {"client_min_messages", PGC_USERSET, LOGGING_WHEN,
+               {"client_min_messages", PGC_USERSET, CLIENT_CONN_STATEMENT,
                        gettext_noop("Sets the message levels that are sent to the client."),
                        gettext_noop("Each level includes all the levels that follow it. The later"
                                                 " the level, the fewer messages are sent.")

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 4e61bc6521fe7497b14ecd983f27b5918d9cf6f7..3fe257c53f1a9341548183b0fe8f4f48ea286e75 100644 (file)
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -406,17 +406,6 @@
 
 # - When to Log -
 
-#client_min_messages = notice          # values in order of decreasing detail:
-                                       #   debug5
-                                       #   debug4
-                                       #   debug3
-                                       #   debug2
-                                       #   debug1
-                                       #   log
-                                       #   notice
-                                       #   warning
-                                       #   error
-
 #log_min_messages = warning            # values in order of decreasing detail:
                                        #   debug5
                                        #   debug4
@@ -561,6 +550,16 @@
 
 # - Statement Behavior -
 
+#client_min_messages = notice          # values in order of decreasing detail:
+                                       #   debug5
+                                       #   debug4
+                                       #   debug3
+                                       #   debug2
+                                       #   debug1
+                                       #   log
+                                       #   notice
+                                       #   warning
+                                       #   error
 #search_path = '"$user", public'       # schema names
 #row_security = on
 #default_tablespace = ''               # a tablespace name, '' uses the default