Re: To deep XML
mysql> SELECT ExtractValue(CONCAT('<root>', repeat('<a>',60), 'b',repeat('</a>',60),'</root>'),'//a');
+-----------------------------------------------------------------------------------------+
| ExtractValue(CONCAT('<root>', repeat('<a>',60), 'b',repeat('</a>',60),'</root>'),'//a') |
+-----------------------------------------------------------------------------------------+
| b |
+-----------------------------------------------------------------------------------------+
mysql> SELECT ExtractValue(CONCAT('<root>', repeat('<a>',62), 'b',repeat('</a>',62),'</root>'),'//a');
+-----------------------------------------------------------------------------------------+
| ExtractValue(CONCAT('<root>', repeat('<a>',62), 'b',repeat('</a>',62),'</root>'),'//a') |
+-----------------------------------------------------------------------------------------+
| NULL |
+-----------------------------------------------------------------------------------------+
1 row in set, 1 warning (0.01 sec)
mysql> show warnings;
+---------+------+-----------------------------------------------------------------------------------------------+
| Level | Code | Message |
+---------+------+-----------------------------------------------------------------------------------------------+
| Warning | 1525 | Incorrect XML value: 'parse error at line 1 pos 197: '</a>' unexpected (END-OF-INPUT wanted)' |
+---------+------+-----------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)