1. 04 Jun, 2010 4 commits
  2. 03 Jun, 2010 5 commits
  3. 02 Jun, 2010 8 commits
  4. 01 Jun, 2010 10 commits
  5. 31 May, 2010 5 commits
  6. 29 May, 2010 1 commit
    • Alexey Kopytov's avatar
      Bug #48537: difference of index selection between rpm binary · 966d6d2f
      Alexey Kopytov authored
                  and .tar.gz, windows vs linux..
      
      On Intel x86 machines index selection by the MySQL query
      optimizer could sometimes depend on the compiler version and
      optimization flags used to build the server binary.
      
      The problem was a result of a known issue with floating point
      calculations on x86: since internal FPU precision (80 bit)
      differs from precision used by programs (32-bit float or 64-bit
      double), the result of calculating a complex expression may
      depend on how FPU registers are allocated by the compiler and
      whether intermediate values are spilled from FPU to memory. In
      this particular case compiler versions and optimization flags
      had an effect on cost calculation when choosing the best index
      in best_access_path().
      
      A possible solution to this problem which has already been
      implemented in mysql-trunk is to limit FPU internal precision
      to 64 bits. So the fix is a backport of the relevant code to
      5.1 from mysql-trunk.
      966d6d2f
  7. 28 May, 2010 5 commits
  8. 27 May, 2010 2 commits
    • Dmitry Lenev's avatar
      Null-merged the 5.1-only version of fix for bug #46947 · fae1efb5
      Dmitry Lenev authored
      "Embedded SELECT without FOR UPDATE is causing a lock"
      into 5.5 tree. One of 5.5 trees already contains a
      more thorough version of the fix.
      fae1efb5
    • Dmitry Lenev's avatar
      A 5.1-only version of fix for bug #46947 "Embedded SELECT · 78c6a8ca
      Dmitry Lenev authored
      without FOR UPDATE is causing a lock".
      
      SELECT statements with subqueries referencing InnoDB tables
      were acquiring shared locks on rows in these tables when they
      were executed in REPEATABLE-READ mode and with statement or
      mixed mode binary logging turned on.
      
      This was a regression which were introduced when fixing
      bug 39843.
      
      The problem was that for tables belonging to subqueries
      parser set TL_READ_DEFAULT as a lock type. In cases when
      statement/mixed binary logging at open_tables() time this
      type of lock was converted to TL_READ_NO_INSERT lock at
      open_tables() time and caused InnoDB engine to acquire
      shared locks on reads from these tables. Although in some
      cases such behavior was correct (e.g. for subqueries in
      DELETE) in case of SELECT it has caused unnecessary locking.
      
      This patch implements minimal version of the fix for the
      specific problem described in the bug-report which supposed
      to be not too risky for pushing into 5.1 tree.
      The 5.5 tree already contains a more appropriate solution
      which also addresses other related issues like bug 53921
      "Wrong locks for SELECTs used stored functions may lead
      to broken SBR".
      
      This patch tries to solve the problem by ensuring that
      TL_READ_DEFAULT lock which is set in the parser for
      tables participating in subqueries at open_tables()
      time is interpreted as TL_READ_NO_INSERT or TL_READ.
      TL_READ is used only if we know that this is a SELECT
      and that this particular table is not used by a stored
      function.
      
      Test coverage is added for both InnoDB and MyISAM.
      
      This patch introduces an "incompatible" change in locking
      scheme for subqueries used in SELECT ... FOR UPDATE and
      SELECT .. IN SHARE MODE.
      
      In 4.1 (as well as in 5.0 and 5.1 before fix for bug 39843)
      the server would use a snapshot InnoDB read for subqueries
      in SELECT FOR UPDATE and SELECT .. IN SHARE MODE statements,
      regardless of whether the binary log is on or off.
      
      If the user required a different type of read (i.e. locking
      read), he/she could request so explicitly by providing FOR
      UPDATE/IN SHARE MODE clause for each individual subquery.
      
      The patch for bug 39843 broke this behaviour (which was not
      documented or tested), and started to use locking reads for
      all subqueries in SELECT ... FOR UPDATE/IN SHARE MODE.
      This patch restores 4.1 behaviour.
      
      This patch should be mostly null-merged into 5.5 tree.
      78c6a8ca