Optimization: in the replication slave, we can avoid doing one strlen() per event's execution,

as we already have db_len in Log_event. Only if rewrite_db() changed the db we need a strlen
(so we now do the strlen() in rewrite_db). Plus a test (we had none for --replicate-rewrite-db :( ).


sql/log_event.cc:
  The goal is to get of rid of one strlen() per replication event in slave:
  we don't need to compute strlen(thd->db) as we already have db_len in the event;
  only case where we need to do a strlen() is if rewrite_db() changed the db.
  Note that db_len is always a meaningful value. It's 0 if event's db is 0.
sql/slave.cc:
  rewrite_db now returns the len of the returned db.
  print_slave_db_safe() needn't call rewrite_db() as rewrite_db() is already called by caller.
sql/slave.h:
  declaration updates for slave.cc

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/slave.h b/sql/slave.h
index 20167094453..97f197fb50a 100644
--- a/sql/slave.h
+++ b/sql/slave.h
@@ -510,8 +510,8 @@ int add_table_rule(HASH* h, const char* table_spec);
 int add_wild_table_rule(DYNAMIC_ARRAY* a, const char* table_spec);
 void init_table_rule_hash(HASH* h, bool* h_inited);
 void init_table_rule_array(DYNAMIC_ARRAY* a, bool* a_inited);
-const char *rewrite_db(const char* db);
-const char *print_slave_db_safe(const char* db);
+const char *rewrite_db(const char* db, uint *new_db_len);
+const char *print_slave_db_safe(const char *db);
 int check_expected_error(THD* thd, RELAY_LOG_INFO* rli, int error_code);
 void skip_load_data_infile(NET* net);
 void slave_print_error(RELAY_LOG_INFO* rli, int err_code, const char* msg, ...);