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.

2 files changed, 21 insertions, 1 deletions

diff --git a/mysql-test/r/range.result b/mysql-test/r/range.result
index b436519d967..f25d94f8066 100644
--- a/mysql-test/r/range.result
+++ b/mysql-test/r/range.result
@@ -649,3 +649,13 @@ OR ((pk4 =1) AND (((pk1 IN ( 7, 2, 1 ))) OR (pk1 =522)) AND ((pk2 IN ( 0, 2635))
 pk1	pk2	pk3	pk4	filler
 2621	2635	1000015	0	filler
 drop table t1, t2;
+create table t1(a char(2), key(a(1)));
+insert into t1 values ('x'), ('xx');
+explain select a from t1 where a > 'x';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	a	a	2	NULL	2	Using where
+select a from t1 where a > 'x';
+a
+xx
+drop table t1;
+End of 4.1 tests
diff --git a/mysql-test/t/range.test b/mysql-test/t/range.test
index 9280911df2c..245178d7d4a 100644
--- a/mysql-test/t/range.test
+++ b/mysql-test/t/range.test
@@ -510,4 +510,14 @@ OR ((pk4 =1) AND (((pk1 IN ( 7, 2, 1 ))) OR (pk1 =522)) AND ((pk2 IN ( 0, 2635))
 ) AND (pk3 >=1000000);
 drop table t1, t2;
 
-# End of 4.1 tests
+#
+# Bug #20732: Partial index and long sjis search with '>' fails sometimes
+#
+
+create table t1(a char(2), key(a(1)));
+insert into t1 values ('x'), ('xx');
+explain select a from t1 where a > 'x';
+select a from t1 where a > 'x';
+drop table t1;
+
+--echo End of 4.1 tests