MDEV-24564 Statistics are lost after ALTER TABLE

Ever since commit 007f68c,
ALTER TABLE no longer invokes handler::open() after
handler::commit_inplace_alter_table().

ha_innobase::reload_statistics(): Reload or recompute statistics
after ALTER TABLE.

innodb_notify_tabledef_changed(): A new function to invoke
ha_innobase::reload_statistics().

handlerton::notify_tabledef_changed(): Add the parameter handler*
so that ha_innobase::reload_statistics() can be invoked.

ha_partition::notify_tabledef_changed(),
partition_notify_tabledef_changed(): Pass through the call
to any partitions or subpartitions.

This is based on code that was supplied by Monty.

Author: dr-m

mysql-test/suite/gcol/r/innodb_virtual_stats.result

@@ -121,5 +121,19 @@ SELECT index_name, stat_name, stat_description
 FROM mysql.innodb_index_stats
 WHERE database_name = 'test' AND table_name = 't';
 index_name	stat_name	stat_description
-# MDEV-24564 FIXME: Do reload statistics after the above ALTER TABLE!
+GEN_CLUST_INDEX	n_diff_pfx01	DB_ROW_ID
+GEN_CLUST_INDEX	n_leaf_pages	Number of leaf pages in the index
+GEN_CLUST_INDEX	size	Number of pages in the index
+idxb	n_diff_pfx01	b
+idxb	n_diff_pfx02	b,DB_ROW_ID
+idxb	n_leaf_pages	Number of leaf pages in the index
+idxb	size	Number of pages in the index
+vidxe	n_diff_pfx01	e
+vidxe	n_diff_pfx02	e,DB_ROW_ID
+vidxe	n_leaf_pages	Number of leaf pages in the index
+vidxe	size	Number of pages in the index
+vidxf	n_diff_pfx01	f
+vidxf	n_diff_pfx02	f,DB_ROW_ID
+vidxf	n_leaf_pages	Number of leaf pages in the index
+vidxf	size	Number of pages in the index
 DROP TABLE t;

mysql-test/suite/gcol/t/innodb_virtual_stats.test

@@ -52,6 +52,5 @@ ALTER TABLE t DROP INDEX vidxcd;
 SELECT index_name, stat_name, stat_description
 FROM mysql.innodb_index_stats
 WHERE database_name = 'test' AND table_name = 't';
--- echo # MDEV-24564 FIXME: Do reload statistics after the above ALTER TABLE!
 
 DROP TABLE t;

sql/ha_partition.cc

@@ -1,6 +1,6 @@
 /*
   Copyright (c) 2005, 2019, Oracle and/or its affiliates.
-  Copyright (c) 2009, 2020, MariaDB
+  Copyright (c) 2009, 2021, MariaDB
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -92,6 +92,61 @@ static handler *partition_create_handler(handlerton *hton,
 static uint partition_flags();
 static alter_table_operations alter_table_flags(alter_table_operations flags);
 
+
+int ha_partition::notify_tabledef_changed(LEX_CSTRING *db,
+                                          LEX_CSTRING *org_table_name,
+                                          LEX_CUSTRING *frm,
+                                          LEX_CUSTRING *version)
+{
+  char from_buff[FN_REFLEN + 1], from_lc_buff[FN_REFLEN + 1];
+  const char *from_path, *name_buffer_ptr, *from;
+  int res= 0;
+  handler **file= m_file;
+  DBUG_ENTER("ha_partition::notify_tabledef_changed");
+
+  from= table->s->normalized_path.str;
+
+  /* setup m_name_buffer_ptr */
+  if (read_par_file(table->s->normalized_path.str))
+    DBUG_RETURN(1);
+
+  from_path= get_canonical_filename(*file, from, from_lc_buff);
+  name_buffer_ptr= m_name_buffer_ptr;
+  do
+  {
+    LEX_CSTRING table_name;
+    const char *table_name_ptr;
+    if (create_partition_name(from_buff, sizeof(from_buff),
+                              from_path, name_buffer_ptr,
+                              NORMAL_PART_NAME, FALSE))
+      res=1;
+    table_name_ptr= from_buff + dirname_length(from_buff);
+
+    lex_string_set3(&table_name, table_name_ptr, strlen(table_name_ptr));
+
+    if (((*file)->ht)->notify_tabledef_changed((*file)->ht, db, &table_name,
+                                               frm, version, *file))
+      res=1;
+    name_buffer_ptr= strend(name_buffer_ptr) + 1;
+  } while (*(++file));
+  DBUG_RETURN(res);
+}
+
+
+static int
+partition_notify_tabledef_changed(handlerton *,
+                                  LEX_CSTRING *db,
+                                  LEX_CSTRING *table,
+                                  LEX_CUSTRING *frm,
+                                  LEX_CUSTRING *version,
+                                  handler *file)
+{
+  DBUG_ENTER("partition_notify_tabledef_changed");
+  DBUG_RETURN(static_cast<ha_partition*>
+              (file)->notify_tabledef_changed(db, table, frm, version));
+}
+
+
 /*
   If frm_error() is called then we will use this to to find out what file
   extensions exist for the storage engine. This is also used by the default
@@ -149,7 +204,9 @@ static int partition_initialize(void *p)
 
   partition_hton->db_type= DB_TYPE_PARTITION_DB;
   partition_hton->create= partition_create_handler;
+
   partition_hton->partition_flags= partition_flags;
+  partition_hton->notify_tabledef_changed= partition_notify_tabledef_changed;
   partition_hton->alter_table_flags= alter_table_flags;
   partition_hton->flags= HTON_NOT_USER_SELECTABLE |
                          HTON_HIDDEN |
@@ -211,25 +268,6 @@ static handler *partition_create_handler(handlerton *hton,
   return file;
 }
 
-/*
-  HA_CAN_PARTITION:
-  Used by storage engines that can handle partitioning without this
-  partition handler
-  (Partition, NDB)
-
-  HA_CAN_UPDATE_PARTITION_KEY:
-  Set if the handler can update fields that are part of the partition
-  function.
-
-  HA_CAN_PARTITION_UNIQUE:
-  Set if the handler can handle unique indexes where the fields of the
-  unique key are not part of the fields of the partition function. Thus
-  a unique key can be set on all fields.
-
-  HA_USE_AUTO_PARTITION
-  Set if the handler sets all tables to be partitioned by default.
-*/
-
 static uint partition_flags()
 {
   return HA_CAN_PARTITION;

sql/ha_partition.h

@@ -3,7 +3,7 @@
 
 /*
    Copyright (c) 2005, 2012, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2020, MariaDB Corporation.
+   Copyright (c) 2009, 2021, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1617,6 +1617,9 @@ class ha_partition :public handler
     return part_recs;
   }
 
+  int notify_tabledef_changed(LEX_CSTRING *db, LEX_CSTRING *table,
+                              LEX_CUSTRING *frm, LEX_CUSTRING *version);
+
   friend int cmp_key_rowid_part_id(void *ptr, uchar *ref1, uchar *ref2);
   friend int cmp_key_part_id(void *key_p, uchar *ref1, uchar *ref2);
   bool can_convert_string(

sql/handler.h

@@ -2,7 +2,7 @@
 #define HANDLER_INCLUDED
 /*
    Copyright (c) 2000, 2019, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2020, MariaDB
+   Copyright (c) 2009, 2021, MariaDB
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
@@ -1681,7 +1681,8 @@ struct handlerton
   */
   int (*notify_tabledef_changed)(handlerton *hton, LEX_CSTRING *db,
                                  LEX_CSTRING *table_name, LEX_CUSTRING *frm,
-                                 LEX_CUSTRING *org_tabledef_version);
+                                 LEX_CUSTRING *org_tabledef_version,
+                                 handler *file);
 
    /*
      System Versioning

sql/sql_table.cc

@@ -1,6 +1,6 @@
 /*
    Copyright (c) 2000, 2019, Oracle and/or its affiliates.
-   Copyright (c) 2010, 2020, MariaDB
+   Copyright (c) 2010, 2021, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -7934,7 +7934,6 @@ static bool mysql_inplace_alter_table(THD *thd,
   Alter_info *alter_info= ha_alter_info->alter_info;
   bool reopen_tables= false;
   bool res;
-  handlerton *hton;
 
   const enum_alter_inplace_result inplace_supported=
     ha_alter_info->inplace_supported;
@@ -8145,20 +8144,22 @@ static bool mysql_inplace_alter_table(THD *thd,
 
   /* Notify the engine that the table definition has changed */
 
-  hton= table->file->partition_ht();
-  if (hton->notify_tabledef_changed)
+  if (table->file->partition_ht()->notify_tabledef_changed)
   {
     char db_buff[FN_REFLEN], table_buff[FN_REFLEN];
+    handlerton *hton= table->file->ht;
     LEX_CSTRING tmp_db, tmp_table;
-    tmp_db.str=    db_buff;
-    tmp_table.str= table_buff;
+
+    tmp_db.str=       db_buff;
+    tmp_table.str=    table_buff;
     tmp_db.length=    tablename_to_filename(table_list->db.str,
                                          db_buff, sizeof(db_buff));
     tmp_table.length= tablename_to_filename(table_list->table_name.str,
                                             table_buff, sizeof(table_buff));
     if ((hton->notify_tabledef_changed)(hton, &tmp_db, &tmp_table,
                                         table->s->frm_image,
-                                        &table->s->tabledef_version))
+                                        &table->s->tabledef_version,
+                                        table->file))
     {
       my_error(HA_ERR_INCOMPATIBLE_DEFINITION, MYF(0));
       DBUG_RETURN(true);

storage/innobase/handler/ha_innodb.cc

@@ -1330,6 +1330,30 @@ innobase_show_status(
 	stat_print_fn*		stat_print,
 	enum ha_stat_type	stat_type);
 
+/** After ALTER TABLE, recompute statistics. */
+inline void ha_innobase::reload_statistics()
+{
+  if (dict_table_t *table= m_prebuilt ? m_prebuilt->table : nullptr)
+  {
+    if (table->is_readable())
+      dict_stats_init(table);
+    else
+      table->stat_initialized= 1;
+  }
+}
+
+/** After ALTER TABLE, recompute statistics. */
+static int innodb_notify_tabledef_changed(handlerton *,
+                                          LEX_CSTRING *, LEX_CSTRING *,
+                                          LEX_CUSTRING *, LEX_CUSTRING *,
+                                          handler *handler)
+{
+  DBUG_ENTER("innodb_notify_tabledef_changed");
+  if (handler)
+    static_cast<ha_innobase*>(handler)->reload_statistics();
+  DBUG_RETURN(0);
+}
+
 /****************************************************************//**
 Parse and enable InnoDB monitor counters during server startup.
 User can enable monitor counters/groups by specifying
@@ -3816,6 +3840,7 @@ static int innodb_init(void* p)
 
 	innobase_hton->flush_logs = innobase_flush_logs;
 	innobase_hton->show_status = innobase_show_status;
+	innobase_hton->notify_tabledef_changed= innodb_notify_tabledef_changed;
 	innobase_hton->flags =
 		HTON_SUPPORTS_EXTENDED_KEYS | HTON_SUPPORTS_FOREIGN_KEYS
 		| HTON_NATIVE_SYS_VERSIONING | HTON_WSREP_REPLICATION;
@@ -16233,6 +16258,7 @@ innobase_show_status(
 	/* Success */
 	return(false);
 }
+
 /*********************************************************************//**
 Returns number of THR_LOCK locks used for one instance of InnoDB table.
 InnoDB no longer relies on THR_LOCK locks so 0 value is returned.

storage/innobase/handler/ha_innodb.h

@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2000, 2017, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2013, 2020, MariaDB Corporation.
+Copyright (c) 2013, 2021, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -211,6 +211,8 @@ class ha_innobase final : public handler
 	int check(THD* thd, HA_CHECK_OPT* check_opt) override;
 	char* update_table_comment(const char* comment) override;
 
+	inline void reload_statistics();
+
 	char* get_foreign_key_create_info() override;
 
         int get_foreign_key_list(THD *thd,

storage/innobase/handler/handler0alter.cc

@@ -11263,12 +11263,18 @@ ha_innobase::commit_inplace_alter_table(
 		&& m_prebuilt->table->n_v_cols
 		&& ha_alter_info->handler_flags & ALTER_STORED_COLUMN_ORDER)) {
 		DBUG_ASSERT(ctx0->old_table->get_ref_count() == 1);
+		ut_ad(ctx0->prebuilt == m_prebuilt);
 		trx_commit_for_mysql(m_prebuilt->trx);
 
-		m_prebuilt->table = innobase_reload_table(m_user_thd,
-							  m_prebuilt->table,
-							  table->s->table_name,
-							  *ctx0);
+		for (inplace_alter_handler_ctx** pctx = ctx_array; *pctx;
+		     pctx++) {
+			auto ctx= static_cast<ha_innobase_inplace_ctx*>(*pctx);
+			ctx->prebuilt->table = innobase_reload_table(
+				m_user_thd, ctx->prebuilt->table,
+				table->s->table_name, *ctx0);
+			innobase_copy_frm_flags_from_table_share(
+				ctx->prebuilt->table, altered_table->s);
+		}
 
 		row_mysql_unlock_data_dictionary(trx);
 		trx->free();

storage/maria/ha_s3.cc

@@ -1,4 +1,4 @@
-/* Copyright (C) 2019, 2020 MariaDB Corporation Ab
+/* Copyright (C) 2019, 2021 MariaDB Corporation Ab
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -887,17 +887,21 @@ int ha_s3::discover_check_version()
   Update the .frm file in S3
 */
 
-static int s3_notify_tabledef_changed(handlerton *hton __attribute__((unused)),
+static int s3_notify_tabledef_changed(handlerton *,
                                       LEX_CSTRING *db, LEX_CSTRING *table,
                                       LEX_CUSTRING *frm,
-                                      LEX_CUSTRING *org_tabledef_version)
+                                      LEX_CUSTRING *org_tabledef_version,
+                                      handler *)
 {
   char aws_path[AWS_PATH_LENGTH];
   S3_INFO s3_info;
   ms3_st *s3_client;
   int error= 0;
   DBUG_ENTER("s3_notify_tabledef_changed");
 
+  if (strstr(table->str, "#P#"))
+    DBUG_RETURN(0);                             // Ignore partitions
+
   if (s3_info_init(&s3_info))
     DBUG_RETURN(0);
   if (!(s3_client= s3_open_connection(&s3_info)))
@@ -916,7 +920,7 @@ static int s3_notify_tabledef_changed(handlerton *hton __attribute__((unused)),
            NullS);
 
   if (s3_put_object(s3_client, s3_info.bucket.str, aws_path, (uchar*) frm->str,
-                         frm->length, 0))
+                    frm->length, 0))
     error= 2;
 
 err: