From 70cb820e2d0bd0a1d1970a312591e87edf3b38ae Mon Sep 17 00:00:00 2001 From: Gleb Shchepa Date: Wed, 5 Dec 2012 16:53:33 +0400 Subject: [PATCH] Bug #15948123: SERVER WORKS INCORRECT WITH LONG TABLE ALIASES Code in MDL subsystem assumes that identifiers of objects can't be longer than NAME_LEN characters. This assumption was broken when one tried to construct MDL_key based on table alias, which can have arbitrary length. Since MDL_key's (and MDL locks) are not really used for table aliases this patch changes code to not initialize MDL_key object for table list element representing aliases. --- sql/mdl.h | 2 ++ sql/sql_parse.cc | 9 +++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/sql/mdl.h b/sql/mdl.h index d30d30ac2fa..6d29ad968c6 100644 --- a/sql/mdl.h +++ b/sql/mdl.h @@ -246,6 +246,8 @@ public: } void mdl_key_init(const MDL_key *rhs) { + DBUG_ASSERT(rhs->m_length <= NAME_LEN); + DBUG_ASSERT(rhs->m_db_name_length <= NAME_LEN); memcpy(m_ptr, rhs->m_ptr, rhs->m_length); m_length= rhs->m_length; m_db_name_length= rhs->m_db_name_length; diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc index 7bbcff4bc2b..534c4cee4c7 100644 --- a/sql/sql_parse.cc +++ b/sql/sql_parse.cc @@ -6000,8 +6000,13 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd, ptr->next_name_resolution_table= NULL; /* Link table in global list (all used tables) */ lex->add_to_query_tables(ptr); - ptr->mdl_request.init(MDL_key::TABLE, ptr->db, ptr->table_name, mdl_type, - MDL_TRANSACTION); + + // Pure table aliases do not need to be locked: + if (!test(table_options & TL_OPTION_ALIAS)) + { + ptr->mdl_request.init(MDL_key::TABLE, ptr->db, ptr->table_name, mdl_type, + MDL_TRANSACTION); + } DBUG_RETURN(ptr); }