Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes

We miss some records sometimes using RANGE method if we have
partial key segments.
Example:
  Create table t1(a char(2), key(a(1)));
  insert into t1 values ('a'), ('xx');
  select a from t1 where a > 'x';
We call index_read() passing 'x' key and HA_READ_AFTER_KEY flag
in the handler::read_range_first() wich is wrong because we have
a partial key segment for the field and might miss records like 'xx'.

Fix: don't use open segments in such a case.


mysql-test/r/range.result:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - test result.
mysql-test/t/range.test:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - test case.
sql/opt_range.cc:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - check if we have a partial key segment for a Item_func::GT_FUNC;
      if so, don't set NEAR_MIN flag in order to use HA_READ_KEY_OR_NEXT
      instead of HA_READ_AFTER_KEY.
sql/opt_range.h:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - key segment 'flag' slot added.
sql/sql_select.cc:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - test (HA_PART_KEY_SEG | HA_NULL_PART) as we split it in the sql/table.cc
sql/table.cc:
  Fix for bug #20732: Partial index and long sjis search with '>' fails sometimes
    - set HA_NULL_PART flag instead of HA_PART_KEY_SEG in order not to mix them.

1 files changed, 5 insertions, 1 deletions

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 6b129997e47..06e42ff363f 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -885,6 +885,7 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
 	key_parts->null_bit=	 key_part_info->null_bit;
         key_parts->image_type =
           (key_info->flags & HA_SPATIAL) ? Field::itMBR : Field::itRAW;
+        key_parts->flag=         key_part_info->key_part_flag;
       }
       param.real_keynr[param.keys++]=idx;
     }
@@ -1398,7 +1399,9 @@ get_mm_leaf(PARAM *param, COND *conf_func, Field *field, KEY_PART *key_part,
     }
     break;
   case Item_func::GT_FUNC:
-    if (field_is_equal_to_item(field,value))
+    /* Don't use open ranges for partial key_segments */
+    if (field_is_equal_to_item(field,value) &&
+        !(key_part->flag & HA_PART_KEY_SEG))
       tree->min_flag=NEAR_MIN;
     /* fall through */
   case Item_func::GE_FUNC:
@@ -2899,6 +2902,7 @@ QUICK_SELECT *get_quick_select_for_ref(THD *thd, TABLE *table, TABLE_REF *ref)
     key_part->length=  	    key_info->key_part[part].length;
     key_part->store_length= key_info->key_part[part].store_length;
     key_part->null_bit=     key_info->key_part[part].null_bit;
+    key_part->flag=         key_info->key_part[part].key_part_flag;
   }
   if (quick->ranges.push_back(range))
     goto err;