Clean up nth_value

Implement nth_value correctly and add a test case for it.

4 files changed, 196 insertions, 29 deletions

diff --git a/mysql-test/r/win_nth_value.result b/mysql-test/r/win_nth_value.result
new file mode 100644
index 00000000000..abda1a2377f
--- /dev/null
+++ b/mysql-test/r/win_nth_value.result
@@ -0,0 +1,120 @@
+create table t1 (
+pk int primary key,
+a int,
+b int,
+c char(10),
+d decimal(10, 3),
+e real
+);
+insert into t1 values
+( 1, 0, 1,    'one',    0.1,  0.001),
+( 2, 0, 2,    'two',    0.2,  0.002),
+( 3, 0, 3,    'three',  0.3,  0.003),
+( 4, 1, 2,    'three',  0.4,  0.004),
+( 5, 1, 1,    'two',    0.5,  0.005),
+( 6, 1, 1,    'one',    0.6,  0.006),
+( 7, 2, NULL, 'n_one',  0.5,  0.007),
+( 8, 2, 1,    'n_two',  NULL, 0.008),
+( 9, 2, 2,    NULL,     0.7,  0.009),
+(10, 2, 0,    'n_four', 0.8,  0.010),
+(11, 2, 10,   NULL,     0.9,  NULL);
+select pk,
+nth_value(pk, 1) over (order by pk),
+nth_value(pk, 2) over (order by pk),
+nth_value(pk, 0) over (order by pk),
+nth_value(pk, -1) over (order by pk),
+nth_value(pk, -2) over (order by pk)
+from t1
+order by pk asc;
+pk	nth_value(pk, 1) over (order by pk)	nth_value(pk, 2) over (order by pk)	nth_value(pk, 0) over (order by pk)	nth_value(pk, -1) over (order by pk)	nth_value(pk, -2) over (order by pk)
+1	1	NULL	NULL	NULL	NULL
+2	1	2	NULL	NULL	NULL
+3	1	2	NULL	NULL	NULL
+4	1	2	NULL	NULL	NULL
+5	1	2	NULL	NULL	NULL
+6	1	2	NULL	NULL	NULL
+7	1	2	NULL	NULL	NULL
+8	1	2	NULL	NULL	NULL
+9	1	2	NULL	NULL	NULL
+10	1	2	NULL	NULL	NULL
+11	1	2	NULL	NULL	NULL
+select pk,
+nth_value(pk, pk) over (order by pk),
+nth_value(pk / 0.1, pk) over (order by pk)
+from t1
+order by pk asc;
+pk	nth_value(pk, pk) over (order by pk)	nth_value(pk / 0.1, pk) over (order by pk)
+1	1	10.0000
+2	2	20.0000
+3	3	30.0000
+4	4	40.0000
+5	5	50.0000
+6	6	60.0000
+7	7	70.0000
+8	8	80.0000
+9	9	90.0000
+10	10	100.0000
+11	11	110.0000
+select pk,
+a,
+nth_value(pk, pk) over (partition by a order by pk),
+nth_value(pk, a + 1) over (partition by a order by pk)
+from t1
+order by pk asc;
+pk	a	nth_value(pk, pk) over (partition by a order by pk)	nth_value(pk, a + 1) over (partition by a order by pk)
+1	0	1	1
+2	0	2	1
+3	0	3	1
+4	1	NULL	NULL
+5	1	NULL	5
+6	1	NULL	5
+7	2	NULL	NULL
+8	2	NULL	NULL
+9	2	NULL	9
+10	2	NULL	9
+11	2	NULL	9
+select pk,
+a,
+nth_value(pk, 1) over (partition by a order by pk ROWS between 1 preceding and 1 following)
+from t1;
+pk	a	nth_value(pk, 1) over (partition by a order by pk ROWS between 1 preceding and 1 following)
+1	0	1
+2	0	1
+3	0	2
+4	1	4
+5	1	4
+6	1	5
+7	2	7
+8	2	7
+9	2	8
+10	2	9
+11	2	10
+select pk,
+a,
+nth_value(a, 1) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 2) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 3) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 4) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 5) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 6) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 7) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 8) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 9) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 10) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 11) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+nth_value(a, 12) over (order by a RANGE BETWEEN 1 preceding and 1 following)
+from t1
+order by pk asc;
+pk	a	nth_value(a, 1) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 2) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 3) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 4) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 5) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 6) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 7) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 8) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 9) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 10) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 11) over (order by a RANGE BETWEEN 1 preceding and 1 following)	nth_value(a, 12) over (order by a RANGE BETWEEN 1 preceding and 1 following)
+1	0	0	0	0	1	1	1	NULL	NULL	NULL	NULL	NULL	NULL
+2	0	0	0	0	1	1	1	NULL	NULL	NULL	NULL	NULL	NULL
+3	0	0	0	0	1	1	1	NULL	NULL	NULL	NULL	NULL	NULL
+4	1	0	0	0	1	1	1	2	2	2	2	2	NULL
+5	1	0	0	0	1	1	1	2	2	2	2	2	NULL
+6	1	0	0	0	1	1	1	2	2	2	2	2	NULL
+7	2	1	1	1	2	2	2	2	2	NULL	NULL	NULL	NULL
+8	2	1	1	1	2	2	2	2	2	NULL	NULL	NULL	NULL
+9	2	1	1	1	2	2	2	2	2	NULL	NULL	NULL	NULL
+10	2	1	1	1	2	2	2	2	2	NULL	NULL	NULL	NULL
+11	2	1	1	1	2	2	2	2	2	NULL	NULL	NULL	NULL
+drop table t1;
diff --git a/mysql-test/t/win_nth_value.test b/mysql-test/t/win_nth_value.test
new file mode 100644
index 00000000000..b9764d1e9d7
--- /dev/null
+++ b/mysql-test/t/win_nth_value.test
@@ -0,0 +1,67 @@
+create table t1 (
+  pk int primary key,
+  a int,
+  b int,
+  c char(10),
+  d decimal(10, 3),
+  e real
+);
+
+insert into t1 values
+( 1, 0, 1,    'one',    0.1,  0.001),
+( 2, 0, 2,    'two',    0.2,  0.002),
+( 3, 0, 3,    'three',  0.3,  0.003),
+( 4, 1, 2,    'three',  0.4,  0.004),
+( 5, 1, 1,    'two',    0.5,  0.005),
+( 6, 1, 1,    'one',    0.6,  0.006),
+( 7, 2, NULL, 'n_one',  0.5,  0.007),
+( 8, 2, 1,    'n_two',  NULL, 0.008),
+( 9, 2, 2,    NULL,     0.7,  0.009),
+(10, 2, 0,    'n_four', 0.8,  0.010),
+(11, 2, 10,   NULL,     0.9,  NULL);
+
+select pk,
+       nth_value(pk, 1) over (order by pk),
+       nth_value(pk, 2) over (order by pk),
+       nth_value(pk, 0) over (order by pk),
+       nth_value(pk, -1) over (order by pk),
+       nth_value(pk, -2) over (order by pk)
+from t1
+order by pk asc;
+
+select pk,
+       nth_value(pk, pk) over (order by pk),
+       nth_value(pk / 0.1, pk) over (order by pk)
+from t1
+order by pk asc;
+
+select pk,
+       a,
+       nth_value(pk, pk) over (partition by a order by pk),
+       nth_value(pk, a + 1) over (partition by a order by pk)
+from t1
+order by pk asc;
+
+select pk,
+       a,
+       nth_value(pk, 1) over (partition by a order by pk ROWS between 1 preceding and 1 following)
+from t1;
+
+select pk,
+       a,
+       nth_value(a, 1) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 2) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 3) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 4) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 5) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 6) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 7) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 8) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 9) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 10) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 11) over (order by a RANGE BETWEEN 1 preceding and 1 following),
+       nth_value(a, 12) over (order by a RANGE BETWEEN 1 preceding and 1 following)
+from t1
+order by pk asc;
+
+drop table t1;
diff --git a/sql/item_windowfunc.h b/sql/item_windowfunc.h
index b3d0b7a15f3..5b368e2cdbc 100644
--- a/sql/item_windowfunc.h
+++ b/sql/item_windowfunc.h
@@ -385,36 +385,11 @@ class Item_sum_last_value : public Item_sum_hybrid_simple
   { return get_item_copy<Item_sum_last_value>(thd, mem_root, this); }
 };
 
-class Item_sum_nth_value : public Item_sum_last_value
+class Item_sum_nth_value : public Item_sum_hybrid_simple
 {
  public:
   Item_sum_nth_value(THD *thd, Item *arg_expr, Item* offset_expr) :
-    Item_sum_last_value(thd, arg_expr) {
-    /* TODO(cvicentiu) This is messy. Item_args starts with 2 args by chance.
-       Clean this up by pulling out the common code from Item_sum_hybrid! */
-    arg_count= 2;
-    args[1]= offset_expr;
-  }
-
-  bool fix_fields(THD *thd, Item **ref)
-  {
-    Item *offset= args[1];
-    if (offset->fix_fields(thd, args))
-      return true;
-    /* Fix fields for the second argument as well. */
-    orig_args[1]= offset;
-    /* Item_sum_last_value fixes fields for first argument only. */
-    if (Item_sum_last_value::fix_fields(thd, ref))
-     return true;
-
-    return false;
-  }
-
-  bool add()
-  {
-    Item_sum_last_value::add();
-    return false;
-  }
+    Item_sum_hybrid_simple(thd, arg_expr, offset_expr) {}
 
   enum Sumfunctype sum_func() const
   {
@@ -788,6 +763,7 @@ public:
     switch (window_func()->sum_func()) {
     case Item_sum::FIRST_VALUE_FUNC:
     case Item_sum::LAST_VALUE_FUNC:
+    case Item_sum::NTH_VALUE_FUNC:
     case Item_sum::LAG_FUNC:
     case Item_sum::LEAD_FUNC:
       return true;
diff --git a/sql/sql_window.cc b/sql/sql_window.cc
index 1a111e52c75..a2fada64a83 100644
--- a/sql/sql_window.cc
+++ b/sql/sql_window.cc
@@ -2205,10 +2205,14 @@ void add_special_frame_cursors(THD *thd, Cursor_manager *cursor_manager,
       cursor_manager->add_cursor(bottom_bound);
       cursor_manager->add_cursor(top_bound);
       DBUG_ASSERT(item_sum->fixed);
+      Item *int_item= new (thd->mem_root) Item_int(thd, 1);
+      Item *offset_func= new (thd->mem_root)
+                              Item_func_minus(thd, item_sum->get_arg(1),
+                                              int_item);
+      offset_func->fix_fields(thd, &offset_func);
       fc= new Frame_positional_cursor(*top_bound,
                                       *top_bound, *bottom_bound,
-                                      *item_sum->get_arg(1),
-                                      false);
+                                      *offset_func, false);
       fc->add_sum_func(item_sum);
       cursor_manager->add_cursor(fc);
       break;