add new HA_NATIVE_SAMPLING flag

3 files changed, 35 insertions, 27 deletions

diff --git a/sql/handler.h b/sql/handler.h
index 305b2afdf6a..58ad863277a 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -366,7 +366,10 @@ enum chf_create_flags {
 /* Implements SELECT ... FOR UPDATE SKIP LOCKED */
 #define HA_CAN_SKIP_LOCKED  (1ULL << 61)
 
-#define HA_LAST_TABLE_FLAG HA_CAN_SKIP_LOCKED
+/* Implements native sampling (MDEV-19556) */
+#define HA_NATIVE_SAMPLING (1ULL << 62)
+
+#define HA_LAST_TABLE_FLAG HA_NATIVE_SAMPLING
 
 
 /* bits in index_flags(index_number) for what you can do with index */
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index ce856bc5204..99c8bbd26b7 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -2634,11 +2634,6 @@ int collect_statistics_for_table(THD *thd, TABLE *table)
   table->collected_stats->cardinality_is_null= TRUE;
   table->collected_stats->cardinality= 0;
 
-  int b = file->sample_next(table->record[0]);
-
-  b += 1;
-
-
   if (thd->variables.sample_percentage == 0)
   {
     if (file->records() < MIN_THRESHOLD_FOR_SAMPLING)
@@ -2663,39 +2658,48 @@ int collect_statistics_for_table(THD *thd, TABLE *table)
 
   restore_record(table, s->default_values);
 
+  if(file->ha_table_flags() & HA_NATIVE_SAMPLING)
+  {
+    rc = -1;
 
+    int b = file->sample_next(table->record[0]);
 
+    b += 1;
 
-
-  /* Perform a full table scan to collect statistics on 'table's columns */
-  if (!(rc= file->ha_rnd_init(TRUE)))
+  }
+  else
   {
-    DEBUG_SYNC(table->in_use, "statistics_collection_start");
 
-    while ((rc= file->ha_rnd_next(table->record[0])) != HA_ERR_END_OF_FILE)
+    /* Perform a full table scan to collect statistics on 'table's columns */
+    if (!(rc= file->ha_rnd_init(TRUE)))
     {
-      if (thd->killed)
-        break;
-
-      if (rc)
-        break;
+      DEBUG_SYNC(table->in_use, "statistics_collection_start");
 
-      if (thd_rnd(thd) <= sample_fraction)
+      while ((rc= file->ha_rnd_next(table->record[0])) != HA_ERR_END_OF_FILE)
       {
-        for (field_ptr= table->field; *field_ptr; field_ptr++)
+        if (thd->killed)
+          break;
+
+        if (rc)
+          break;
+
+        if (thd_rnd(thd) <= sample_fraction)
         {
-          table_field= *field_ptr;
-          if (!table_field->collected_stats)
-            continue;
-          if ((rc= table_field->collected_stats->add()))
+          for (field_ptr= table->field; *field_ptr; field_ptr++)
+          {
+            table_field= *field_ptr;
+            if (!table_field->collected_stats)
+              continue;
+            if ((rc= table_field->collected_stats->add()))
+              break;
+          }
+          if (rc)
             break;
+          rows++;
         }
-        if (rc)
-          break;
-        rows++;
       }
+      file->ha_rnd_end();
     }
-    file->ha_rnd_end();
   }
   rc= (rc == HA_ERR_END_OF_FILE && !thd->killed) ? 0 : 1;
 
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 9d9a4453588..b1d68485a96 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -3020,7 +3020,8 @@ ha_innobase::ha_innobase(
                           | HA_CAN_ONLINE_BACKUPS
 			  | HA_CONCURRENT_OPTIMIZE
 			  | HA_CAN_SKIP_LOCKED
-			  |  (srv_force_primary_key ? HA_REQUIRE_PRIMARY_KEY : 0)
+			  |  (srv_force_primary_key ? HA_REQUIRE_PRIMARY_KEY : 0
+                          | HA_NATIVE_SAMPLING)
 		  ),
 	m_start_of_scan(),
         m_mysql_has_locked()