1. 06 Mar, 2007 7 commits
    • malff/marcsql@weblab.(none)'s avatar
      Merge malff@bk-internal.mysql.com:/home/bk/mysql-5.1-runtime · e648fb17
      malff/marcsql@weblab.(none) authored
      into  weblab.(none):/home/marcsql/TREE/mysql-5.1-8407-merge
      e648fb17
    • malff/marcsql@weblab.(none)'s avatar
      Manual merge · fedd1ae7
      malff/marcsql@weblab.(none) authored
      fedd1ae7
    • kostja@bodhi.local's avatar
      Post-merge fixes. · d0cc0355
      kostja@bodhi.local authored
      d0cc0355
    • malff/marcsql@weblab.(none)'s avatar
      Merge weblab.(none):/home/marcsql/TREE/mysql-5.0-8407_b · 8643745d
      malff/marcsql@weblab.(none) authored
      into  weblab.(none):/home/marcsql/TREE/mysql-5.1-8407-merge
      8643745d
    • kostja@bodhi.local's avatar
      Merge bodhi.local:/opt/local/work/mysql-5.0-runtime · 92b44016
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.1-runtime-merge
      92b44016
    • kostja@bodhi.local's avatar
      Merge bk-internal.mysql.com:/home/bk/mysql-5.1-new-rpl · 3d488d49
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.1-runtime-merge
      3d488d49
    • malff/marcsql@weblab.(none)'s avatar
      Bug#8407 (Stored functions/triggers ignore exception handler) · b216d959
      malff/marcsql@weblab.(none) authored
      Bug 18914 (Calling certain SPs from triggers fail)
      Bug 20713 (Functions will not not continue for SQLSTATE VALUE '42S02')
      Bug 21825 (Incorrect message error deleting records in a table with a
        trigger for inserting)
      Bug 22580 (DROP TABLE in nested stored procedure causes strange dependency
        error)
      Bug 25345 (Cursors from Functions)
      
      
      This fix resolves a long standing issue originally reported with bug 8407,
      which affect the behavior of Stored Procedures, Stored Functions and Trigger
      in many different ways, causing symptoms reported by all the bugs listed.
      In all cases, the root cause of the problem traces back to 8407 and how the
      server locks tables involved with sub statements.
      
      Prior to this fix, the implementation of stored routines would:
      - compute the transitive closure of all the tables referenced by a top level
      statement
      - open and lock all the tables involved
      - execute the top level statement
      "transitive closure of tables" means collecting:
      - all the tables,
      - all the stored functions,
      - all the views,
      - all the table triggers
      - all the stored procedures
      involved, and recursively inspect these objects definition to find more
      references to more objects, until the list of every object referenced does
      not grow any more.
      This mechanism is known as "pre-locking" tables before execution.
      The motivation for locking all the tables (possibly) used at once is to
      prevent dead locks.
      
      One problem with this approach is that, if the execution path the code
      really takes during runtime does not use a given table, and if the table is
      missing, the server would not execute the statement.
      This in particular has a major impact on triggers, since a missing table
      referenced by an update/delete trigger would prevent an insert trigger to run.
      
      Another problem is that stored routines might define SQL exception handlers
      to deal with missing tables, but the server implementation would never give
      user code a chance to execute this logic, since the routine is never
      executed when a missing table cause the pre-locking code to fail.
      
      With this fix, the internal implementation of the pre-locking code has been
      relaxed of some constraints, so that failure to open a table does not
      necessarily prevent execution of a stored routine.
      
      In particular, the pre-locking mechanism is now behaving as follows:
      
      1) the first step, to compute the transitive closure of all the tables
      possibly referenced by a statement, is unchanged.
      
      2) the next step, which is to open all the tables involved, only attempts
      to open the tables added by the pre-locking code, but silently fails without
      reporting any error or invoking any exception handler is the table is not
      present. This is achieved by trapping internal errors with
      Prelock_error_handler
      
      3) the locking step only locks tables that were successfully opened.
      
      4) when executing sub statements, the list of tables used by each statements
      is evaluated as before. The tables needed by the sub statement are expected
      to be already opened and locked. Statement referencing tables that were not
      opened in step 2) will fail to find the table in the open list, and only at
      this point will execution of the user code fail.
      
      5) when a runtime exception is raised at 4), the instruction continuation
      destination (the next instruction to execute in case of SQL continue
      handlers) is evaluated.
      This is achieved with sp_instr::exec_open_and_lock_tables()
      
      6) if a user exception handler is present in the stored routine, that
      handler is invoked as usual, so that ER_NO_SUCH_TABLE exceptions can be
      trapped by stored routines. If no handler exists, then the runtime execution
      will fail as expected.
      
      With all these changes, a side effect is that view security is impacted, in
      two different ways.
      
      First, a view defined as "select stored_function()", where the stored
      function references a table that may not exist, is considered valid.
      The rationale is that, because the stored function might trap exceptions
      during execution and still return a valid result, there is no way to decide
      when the view is created if a missing table really cause the view to be invalid.
      
      Secondly, testing for existence of tables is now done later during
      execution. View security, which consist of trapping errors and return a
      generic ER_VIEW_INVALID (to prevent disclosing information) was only
      implemented at very specific phases covering *opening* tables, but not
      covering the runtime execution. Because of this existing limitation,
      errors that were previously trapped and converted into ER_VIEW_INVALID are
      not trapped, causing table names to be reported to the user.
      This change is exposing an existing problem, which is independent and will
      be resolved separately.
      b216d959
  2. 05 Mar, 2007 1 commit
  3. 02 Mar, 2007 9 commits
  4. 01 Mar, 2007 23 commits