Bug#10178 - failure to find a row in heap table by concurrent UPDATEs

Bug#10568 - Function 'LAST_DAY(date)' does not return NULL for invalid argument.
Manual merge.


include/my_global.h:
  Auto merged
mysql-test/t/heap_hash.test:
  Auto merged
sql/ha_heap.h:
  Auto merged
sql/item_timefunc.cc:
  Auto merged
mysql-test/r/func_time.result:
  Manual merge.
  Used local for the backported fix for Bug#10568.
mysql-test/r/heap_hash.result:
  Bug#10178 - failure to find a row in heap table by concurrent UPDATEs
  Manual merge.
mysql-test/t/func_time.test:
  Manual merge.
  Used local for the backported fix for Bug#10568.
sql/ha_heap.cc:
  Bug#10178 - failure to find a row in heap table by concurrent UPDATEs
  Manual merge.

1 files changed, 25 insertions, 5 deletions

diff --git a/sql/ha_heap.cc b/sql/ha_heap.cc
index cd655eeb0a9..6e609a94be3 100644
--- a/sql/ha_heap.cc
+++ b/sql/ha_heap.cc
@@ -65,7 +65,15 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
   {
     /* Initialize variables for the opened table */
     set_keys_for_scanning();
-    update_key_stats();
+    /*
+      We cannot run update_key_stats() here because we do not have a
+      lock on the table. The 'records' count might just be changed
+      temporarily at this moment and we might get wrong statistics (Bug
+      #10178). Instead we request for update. This will be done in
+      ha_heap::info(), which is always called before key statistics are
+      used.
+    */
+    key_stats_ok= FALSE;
   }
   return (file ? 0 : 1);
 }
@@ -118,6 +126,8 @@ void ha_heap::update_key_stats()
     }
   }
   records_changed= 0;
+  /* At the end of update_key_stats() we can proudly claim they are OK. */
+  key_stats_ok= TRUE;
 }
 
 
@@ -132,7 +142,7 @@ int ha_heap::write_row(byte * buf)
   res= heap_write(file,buf);
   if (!res && (++records_changed*HEAP_STATS_UPDATE_THRESHOLD > 
                file->s->records))
-    update_key_stats();
+    key_stats_ok= FALSE;
   return res;
 }
 
@@ -145,7 +155,7 @@ int ha_heap::update_row(const byte * old_data, byte * new_data)
   res= heap_update(file,old_data,new_data);
   if (!res && ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > 
               file->s->records)
-    update_key_stats();
+    key_stats_ok= FALSE;
   return res;
 }
 
@@ -156,7 +166,7 @@ int ha_heap::delete_row(const byte * buf)
   res= heap_delete(file,buf);
   if (!res && table->s->tmp_table == NO_TMP_TABLE && 
       ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > file->s->records)
-    update_key_stats();
+    key_stats_ok= FALSE;
   return res;
 }
 
@@ -278,6 +288,13 @@ void ha_heap::info(uint flag)
   delete_length= info.deleted * info.reclength;
   if (flag & HA_STATUS_AUTO)
     auto_increment_value= info.auto_increment;
+  /*
+    If info() is called for the first time after open(), we will still
+    have to update the key statistics. Hoping that a table lock is now
+    in place.
+  */
+  if (! key_stats_ok)
+    update_key_stats();
 }
 
 int ha_heap::extra(enum ha_extra_function operation)
@@ -289,7 +306,7 @@ int ha_heap::delete_all_rows()
 {
   heap_clear(file);
   if (table->s->tmp_table == NO_TMP_TABLE)
-    update_key_stats();
+    key_stats_ok= FALSE;
   return 0;
 }
 
@@ -448,6 +465,9 @@ ha_rows ha_heap::records_in_range(uint inx, key_range *min_key,
       min_key->flag != HA_READ_KEY_EXACT ||
       max_key->flag != HA_READ_AFTER_KEY)
     return HA_POS_ERROR;			// Can only use exact keys
+
+  /* Assert that info() did run. We need current statistics here. */
+  DBUG_ASSERT(key_stats_ok);
   return key->rec_per_key[key->key_parts-1];
 }