Add capability to suppress CONTEXT: messages to elog machinery.

Hiding context messages usually is not a good idea - except for rather
verbose debugging/development utensils like LOG_DEBUG. There the
amount of repeated context messages just bloat the log without adding
information.

src/backend/utils/error/elog.c

@@ -1081,6 +1081,25 @@ errhidestmt(bool hide_stmt)
 	return 0;					/* return value does not matter */
 }
 
+/*
+ * errhidestmt --- optionally suppress CONTEXT: field of log entry
+ *
+ * This should only be used for verbose debugging messages where the repeated
+ * inclusion of CONTEXT: bloats the log volume too much.
+ */
+int
+errhidecontext(bool hide_ctx)
+{
+	ErrorData  *edata = &errordata[errordata_stack_depth];
+
+	/* we don't bother incrementing recursion_depth */
+	CHECK_STACK_DEPTH();
+
+	edata->hide_ctx = hide_ctx;
+
+	return 0;					/* return value does not matter */
+}
+
 
 /*
  * errfunction --- add reporting function name to the current error
@@ -2724,6 +2743,7 @@ write_csvlog(ErrorData *edata)
 	appendStringInfoChar(&buf, ',');
 
 	/* errcontext */
+	if (!edata->hide_ctx)
 		appendCSVLiteral(&buf, edata->context);
 	appendStringInfoChar(&buf, ',');
 
@@ -2856,7 +2876,7 @@ send_message_to_server_log(ErrorData *edata)
 			append_with_tabs(&buf, edata->internalquery);
 			appendStringInfoChar(&buf, '\n');
 		}
-		if (edata->context)
+		if (edata->context && !edata->hide_ctx)
 		{
 			log_line_prefix(&buf, edata);
 			appendStringInfoString(&buf, _("CONTEXT:  "));

src/include/utils/elog.h

@@ -221,6 +221,7 @@ errcontext_msg(const char *fmt,...)
 __attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
 
 extern int	errhidestmt(bool hide_stmt);
+extern int	errhidecontext(bool hide_ctx);
 
 extern int	errfunction(const char *funcname);
 extern int	errposition(int cursorpos);
@@ -385,6 +386,7 @@ typedef struct ErrorData
 	bool		output_to_client;		/* will report to client? */
 	bool		show_funcname;	/* true to force funcname inclusion */
 	bool		hide_stmt;		/* true to prevent STATEMENT: inclusion */
+	bool		hide_ctx;		/* true to prevent CONTEXT: inclusion */
 	const char *filename;		/* __FILE__ of ereport() call */
 	int			lineno;			/* __LINE__ of ereport() call */
 	const char *funcname;		/* __func__ of ereport() call */