Do not copy query texts when listing tracked statements

As already CStringGetTextDatum() copies the strings there is no reason
to run pstrdup(). Additionally make the variable name more consistent
with other variables and move the dsa reference to the right scope.

Author: jeltz

src/pg_stat_monitor.c

@@ -2074,22 +2074,20 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
 		uint32		ip = entry->key.ip;
 		int64		planid = entry->key.planid;
 		int64		pgsm_query_id = entry->pgsm_query_id;
-		dsa_area   *query_dsa_area;
-		char	   *query_ptr;
-		char	   *query_txt;
-		char	   *parent_query_txt = NULL;
+		char	   *query_text;
+		char	   *parent_query_text = NULL;
 		bool		toplevel = entry->key.toplevel;
 
 		/* Load the query text from dsa area */
 		if (DsaPointerIsValid(entry->query_text.query_pos))
 		{
+			dsa_area   *query_dsa_area;
+
 			query_dsa_area = get_dsa_area_for_query_text();
-			query_ptr = dsa_get_address(query_dsa_area, entry->query_text.query_pos);
-			query_txt = pstrdup(query_ptr);
+			query_text = dsa_get_address(query_dsa_area, entry->query_text.query_pos);
 		}
 		else
-			query_txt = pstrdup("Query string not available");	/* Should never happen.
-																 * Just a safety check */
+			query_text = "Query string not available";	/* Should never happen */
 
 		/* copy counters to a local variable to keep locking time short */
 		SpinLockAcquire(&entry->mutex);
@@ -2112,12 +2110,13 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
 		{
 			if (DsaPointerIsValid(tmp.info.parent_query))
 			{
+				dsa_area   *query_dsa_area;
+
 				query_dsa_area = get_dsa_area_for_query_text();
-				query_ptr = dsa_get_address(query_dsa_area, tmp.info.parent_query);
-				parent_query_txt = pstrdup(query_ptr);
+				parent_query_text = dsa_get_address(query_dsa_area, tmp.info.parent_query);
 			}
 			else
-				parent_query_txt = pstrdup("parent query text not available");
+				parent_query_text = "parent query text not available";
 		}
 
 		/* bucketid at column number 0 */
@@ -2158,7 +2157,7 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
 			if (showtext)
 			{
 				/* query at column number 8 */
-				values[i++] = CStringGetTextDatum(query_txt);
+				values[i++] = CStringGetTextDatum(query_text);
 				/* plan at column number 9 */
 				if (planid && tmp.planinfo.plan_text[0])
 					values[i++] = CStringGetTextDatum(tmp.planinfo.plan_text);
@@ -2190,7 +2189,7 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
 		if (tmpkey.parentid != INT64CONST(0))
 		{
 			values[i++] = Int64GetDatum(tmpkey.parentid);
-			values[i++] = CStringGetTextDatum(parent_query_txt);
+			values[i++] = CStringGetTextDatum(parent_query_text);
 		}
 		else
 		{
@@ -2410,11 +2409,6 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
 
 		/* clean up and return the tuplestore */
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
-
-		if (query_txt)
-			pfree(query_txt);
-		if (parent_query_txt)
-			pfree(parent_query_txt);
 	}
 	/* clean up and return the tuplestore */
 	pgsm_lock_release(pgsm);