BUG#20357 - Got error 124 from storage engine using MIN and MAX

            functions in queries

Using MAX()/MIN() on table with disabled indexes (by ALTER TABLE)
results in error 124 (wrong index) from storage engine.

The problem was that optimizer use disabled index to optimize
MAX()/MIN(). Normally it must skip disabled index and perform
table scan.

This patch skips disabled indexes for min/max optimization.


mysql-test/r/myisam.result:
  Test case for BUG#20357.
mysql-test/t/myisam.test:
  Test case for BUG#20357.
sql/opt_sum.cc:
  Skip disabled/ignored indexes for min/max optimization.

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/opt_sum.cc b/sql/opt_sum.cc
index cfb5b3695a3..63373a8579a 100644
--- a/sql/opt_sum.cc
+++ b/sql/opt_sum.cc
@@ -673,6 +673,12 @@ static bool find_key_for_maxmin(bool max_fl, TABLE_REF *ref,
   {
     KEY_PART_INFO *part,*part_end;
     key_part_map key_part_to_use= 0;
+    /*
+      Perform a check if index is not disabled by ALTER TABLE
+      or IGNORE INDEX.
+    */
+    if (!table->keys_in_use_for_query.is_set(idx))
+      continue;
     uint jdx= 0;
     *prefix_len= 0;
     for (part= keyinfo->key_part, part_end= part+keyinfo->key_parts ;