• Kristofer Pettersson's avatar
    Bug#39843 DELETE requires write access to table in subquery in where clause · ddaede80
    Kristofer Pettersson authored
    An unnecessarily restrictive lock were taken on sub-SELECTs during DELETE.
    
    During parsing, a global structure is reused for sub-SELECTs and the attribute
    keeping track of lock options were not reset properly.
    This patch introduces a new attribute to keep track on the syntactical lock
    option elements found in a sub-SELECT and then sets the lock options accordingly.
    
    Now the sub-SELECTs will try to acquire a READ lock if possible
    instead of a WRITE lock as inherited from the outer DELETE statement.
    
    
    mysql-test/r/lock.result:
      Added test case for bug39843
    mysql-test/t/lock.test:
      Added test case for bug39843
    sql/sql_lex.cc:
      * Reset member variable lock_option on each new query.
    sql/sql_lex.h:
      * Introduced new member variable 'lock_option' which is keeping track
        of the syntactical lock option of a (sub-)select query.
    sql/sql_parse.cc:
      * Wrote comments to functions.
    sql/sql_yacc.yy:
      * Introduced an attribute to keep track of syntactical lock options
        in sub-selects.
      * Made sure that the default value TL_READ_DEFAULT is at the begining
        of each subselect-rule.
    ddaede80
sql_lex.h 57.6 KB