I am interested in the mysql user activity monitoring patch that
Google has. They have not released each feature as a separate patch
and instead have given out one-big-patch-file 
. Preliminary
analysis shows that user accounting requires modifications to be
applied in these files. The numbers in the second column are the
number of lines modified in the original file via the patch. The
output was generated using egrep and diffstat.
| libmysqld/sql_parse.cc | 509 |
| libmysqld/sql_show.cc | 137 |
| libmysqld/sql_yacc.cc | 31182 |
| sql/lex.h | 7 |
| sql/lex_hash.h | 12442 |
| sql/mysqld.cc | 338 |
| sql/mysql_priv.h | 111 |
| sql/sql_class.h | 159 |
| sql/sql_lex.h | 10 |
| sql/sql_parse.cc | 514 |
| sql/sql_show.cc | 137 |
| sql/sql_yacc.cc | 31182 |
| sql/sql_yacc.h | 1431 |
| sql/sql_yacc.yy | 103 |
| sql/structs.h | 22 |