Backport into MariaDB-5.2 the following:

WL#2474 "Multi Range Read: Change the default MRR implementation to implement new MRR interface"
WL#2475 "Batched range read functions for MyISAM/InnoDb"
        "Index condition pushdown for MyISAM/InnoDB"
Igor's fix from sp1r-igor@olga.mysql.com-20080330055902-07614:
  There could be observed the following problems:
  1. EXPLAIN did not mention pushdown conditions from on expressions in the 
  'extra' column.  As a result if a query had no where conditions pushed 
  down to a table, but had on conditions pushed to this table the 'extra' 
  column in the EXPLAIN for the table missed 'using where'.
  2. Conditions for ref access were not eliminated from on expressions 
  though such conditions were eliminated from the where condition.

1 files changed, 29 insertions, 0 deletions

diff --git a/mysql-test/suite/optimizer_unfixed_bugs/README.txt b/mysql-test/suite/optimizer_unfixed_bugs/README.txt
new file mode 100644
index 00000000000..ddf65555ce2
--- /dev/null
+++ b/mysql-test/suite/optimizer_unfixed_bugs/README.txt
@@ -0,0 +1,29 @@
+Putting testcases here
+~~~~~~~~~~~~~~~~~~~~~~
+
+When you work on re-verifying or re-classifying a bug (not fixing it),
+it's a good idea to put the mtr-parsable '.test' testcase here.
+Benefits:
+1) tests downloaded from the bugs db are sometimes close to
+mtr-parsable but not completely (for example if they contain
+/* comment */); when you re-verify or re-classify you run the test so
+may have to make it mtr-parsable; if you then put it in this suite,
+the developer who will work on this bug in a few weeks or months will
+not have to re-do the same download&fix, she/he can instead reuse your
+work.
+2) Others can see how their own work influences many unsolved
+bugs, by running this suite. If they find that they fix a bug in this
+suite, we won't later wonder "how come this bug doesn't happen
+anymore, what fixed it?".
+3) One can also run this suite with certain switches to see how they
+influence unsolved bugs:
+./mtr --suite=optimizer_unfixed_bugs \
+--mysqld=--optimizer_switch="firstmatch=off"
+
+Adding tests to this suite
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+One test file per bug, named bugNNNNN.test.
+Put the correct (not current and buggy) result file in r/, so that "[ pass ]"
+in mtr will mean that a bug looks like fixed.
+When you have fixed a bug, remove files from this suite.
+t/bug45219.test is an example.