MDEV-22401: Optimizer trace: multi-component range is not printed correctlybb-10.4-mdev22401

KEY_MULTI_RANGE::range_flag does not have correct flag bits for
per-endpoint flags (NEAR_MIN, NEAR_MAX, NO_MIN_RANGE, NO_MAX_RANGE).
It only has bits for flags that describe both endpoints.
So
- Document this.
- Switch optimizer trace to using {start|end}_key.flag values, instead.
  This fixes the bug.
- Switch records_in_column_ranges() to doing that too. (This used to
  work, because KEY_MULTI_RANGE::range_flag had correct flag value
  for the last key component, and EITS only uses one-component
  pseudo-indexes)

2 files changed, 24 insertions, 9 deletions

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 312999ddc17..a3c5dbcb199 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -3206,8 +3206,18 @@ double records_in_column_ranges(PARAM *param, uint idx,
     key_range *min_endp, *max_endp;
     min_endp= range.start_key.length? &range.start_key : NULL;
     max_endp= range.end_key.length? &range.end_key : NULL;
-    rows= get_column_range_cardinality(field, min_endp, max_endp,
-                                       range.range_flag);
+    int range_flag= range.range_flag;
+
+    if (!range.start_key.length)
+      range_flag |= NO_MIN_RANGE;
+    if (!range.end_key.length)
+      range_flag |= NO_MAX_RANGE;
+    if (range.start_key.flag == HA_READ_AFTER_KEY)
+      range_flag |= NEAR_MIN;
+    if (range.start_key.flag == HA_READ_BEFORE_KEY)
+      range_flag |= NEAR_MAX;
+
+    rows= get_column_range_cardinality(field, min_endp, max_endp, range_flag);
     if (DBL_MAX == rows)
     {
       total_rows= DBL_MAX;
@@ -15814,24 +15824,29 @@ void print_range(String *out, const KEY_PART_INFO *key_part,
     return;
   }
 
-  if (!(flag & NO_MIN_RANGE))
+  if (range->start_key.length)
   {
     print_key_value(out, key_part, range->start_key.key,
                     range->start_key.length);
-    if (flag & NEAR_MIN)
+    if (range->start_key.flag == HA_READ_AFTER_KEY)
       out->append(STRING_WITH_LEN(" < "));
-    else
+    else if (range->start_key.flag == HA_READ_KEY_EXACT ||
+             range->start_key.flag == HA_READ_KEY_OR_NEXT)
       out->append(STRING_WITH_LEN(" <= "));
+    else
+      out->append(STRING_WITH_LEN(" ? "));
   }
 
   print_keyparts_name(out, key_part, n_key_parts, keypart_map);
 
-  if (!(flag & NO_MAX_RANGE))
+  if (range->end_key.length)
   {
-    if (flag & NEAR_MAX)
+    if (range->end_key.flag == HA_READ_BEFORE_KEY)
       out->append(STRING_WITH_LEN(" < "));
-    else
+    else if (range->end_key.flag == HA_READ_AFTER_KEY)
       out->append(STRING_WITH_LEN(" <= "));
+    else
+      out->append(STRING_WITH_LEN(" ? "));
     print_key_value(out, key_part, range->end_key.key,
                     range->end_key.length);
   }
diff --git a/sql/opt_range_mrr.cc b/sql/opt_range_mrr.cc
index 4afa06a7ca0..267d764bb3b 100644
--- a/sql/opt_range_mrr.cc
+++ b/sql/opt_range_mrr.cc
@@ -262,7 +262,6 @@ walk_up_n_right:
   else
   {
     max_key_parts= MY_MAX(cur->min_key_parts, cur->max_key_parts);
-    range->range_flag= cur->min_key_flag | cur->max_key_flag;
     
     range->start_key.key=    seq->param->min_key;
     range->start_key.length= (uint)(cur->min_key - seq->param->min_key);
@@ -298,6 +297,7 @@ walk_up_n_right:
         !memcmp(seq->param->min_key, seq->param->max_key,    // (2)
                 range->start_key.length);
 
+    range->range_flag= 0;
     if (is_eq_range_pred)
     {
       range->range_flag = EQ_RANGE;