Add GUC backtrace_on_internal_error

When enabled (default off), this logs a backtrace anytime elog() or an
equivalent ereport() for internal errors is called.

This is not well covered by the existing backtrace_functions, because
there are many equally-worded low-level errors in many functions.  And
if you find out where the error is, then you need to manually rewrite
the elog() to ereport() to attach the errbacktrace(), which is
annoying.  Having a backtrace automatically on every elog() call could
be very helpful during development for various kinds of common errors
from palloc, syscache, node support, etc.

Discussion: https://www.postgresql.org/message-id/flat/ba76c6bc-f03f-4285-bf16-47759cfcab9e@eisentraut.org

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index b5624ca8847..f323bba018f 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -11086,6 +11086,33 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-backtrace-on-internal-error" xreflabel="backtrace_on_internal_error">
+      <term><varname>backtrace_on_internal_error</varname> (<type>boolean</type>)
+      <indexterm>
+        <primary><varname>backtrace_on_internal_error</varname> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        If this parameter is on and an error with error code XX000 (internal
+        error; see also <xref linkend="errcodes-appendix"/>) is raised, then a
+        backtrace is written to the server log together with the error
+        message.  This can be used to debug such internal errors (which should
+        normally not happen in production).  The default is off.
+       </para>
+
+       <para>
+        Backtrace support is not available on all platforms, and the quality
+        of the backtraces depends on compilation options.
+       </para>
+
+       <para>
+        Only superusers and users with the appropriate <literal>SET</literal>
+        privilege can change this setting.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-debug-discard-caches" xreflabel="debug_discard_caches">
       <term><varname>debug_discard_caches</varname> (<type>integer</type>)
       <indexterm>