MDEV-18295 IMPORT TABLESPACE fails with instant-altered tables

When importing a tablespace, we must initialize dummy DEFAULT NULL
values for any instantly added columns in order to avoid a debug
assertion failure when PageConverter::update_records() invokes
rec_get_offsets(). Finally, when the operation completes, we must
evict and reload the table definition, so that the correct
default values for instantly added columns will be loaded.

ha_innobase::discard_or_import_tablespace(): On successful
IMPORT TABLESPACE, evict and reload the table definition,
so that btr_cur_instant_init() will load the correct metadata.

PageConverter::update_index_page(): Fill in dummy DEFAULT NULL values
for instantly added columns. These will be replaced upon the
completion of the operation by evicting and reloading the metadata.

row_discard_tablespace(): Invoke dict_table_t::remove_instant().
After DISCARD TABLESPACE, the table is no longer in "instant ALTER"
format, because there is no data file attached.

mysql-test/suite/innodb/r/instant_alter_import.result

@@ -0,0 +1,46 @@
+set default_storage_engine=innodb;
+#
+# MDEV-18295 IMPORT TABLESPACE fails with instant-altered tables
+#
+create table t2 (x int, z int default 41);
+alter table t2 discard tablespace;
+create table t1 (x int);
+insert into t1 values (1);
+alter table t1 add z int default 42, algorithm instant;
+select * from t1;
+x	z
+1	42
+flush tables t1 for export;
+unlock tables;
+# The metadata has to be updated to instant ADD COLUMN.
+alter table t2 import tablespace;
+select * from t2;
+x	z
+1	42
+insert into t2 set x=2;
+select * from t2;
+x	z
+1	42
+2	41
+alter table t1 discard tablespace;
+flush tables t2 for export;
+unlock tables;
+# Both the metadata and the data file used instant ADD COLUMN.
+alter table t1 import tablespace;
+select * from t1;
+x	z
+1	42
+2	41
+drop table t2;
+create table t2 select * from t1;
+alter table t1 discard tablespace;
+flush tables t2 for export;
+unlock tables;
+# The instant ADD COLUMN has to be removed from the metadata.
+alter table t1 import tablespace;
+select * from t1;
+x	z
+1	42
+2	41
+drop table t2;
+drop table t1;

mysql-test/suite/innodb/t/instant_alter_import.test

@@ -0,0 +1,52 @@
+--source include/have_innodb.inc
+set default_storage_engine=innodb;
+
+--echo #
+--echo # MDEV-18295 IMPORT TABLESPACE fails with instant-altered tables
+--echo #
+
+create table t2 (x int, z int default 41);
+alter table t2 discard tablespace;
+
+create table t1 (x int);
+insert into t1 values (1);
+alter table t1 add z int default 42, algorithm instant;
+select * from t1;
+flush tables t1 for export;
+--let $MYSQLD_DATADIR= `select @@datadir`
+--move_file $MYSQLD_DATADIR/test/t1.cfg $MYSQLD_DATADIR/test/t2.cfg
+--copy_file $MYSQLD_DATADIR/test/t1.ibd $MYSQLD_DATADIR/test/t2.ibd
+unlock tables;
+
+--echo # The metadata has to be updated to instant ADD COLUMN.
+alter table t2 import tablespace;
+
+select * from t2;
+insert into t2 set x=2;
+select * from t2;
+
+alter table t1 discard tablespace;
+flush tables t2 for export;
+--move_file $MYSQLD_DATADIR/test/t2.cfg $MYSQLD_DATADIR/test/t1.cfg
+--copy_file $MYSQLD_DATADIR/test/t2.ibd $MYSQLD_DATADIR/test/t1.ibd
+unlock tables;
+
+--echo # Both the metadata and the data file used instant ADD COLUMN.
+alter table t1 import tablespace;
+select * from t1;
+
+drop table t2;
+create table t2 select * from t1;
+
+alter table t1 discard tablespace;
+flush tables t2 for export;
+--move_file $MYSQLD_DATADIR/test/t2.cfg $MYSQLD_DATADIR/test/t1.cfg
+--copy_file $MYSQLD_DATADIR/test/t2.ibd $MYSQLD_DATADIR/test/t1.ibd
+unlock tables;
+
+--echo # The instant ADD COLUMN has to be removed from the metadata.
+alter table t1 import tablespace;
+select * from t1;
+
+drop table t2;
+drop table t1;

storage/innobase/handler/ha_innodb.cc

@@ -4,7 +4,7 @@ Copyright (c) 2000, 2018, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, 2009 Google Inc.
 Copyright (c) 2009, Percona Inc.
 Copyright (c) 2012, Facebook Inc.
-Copyright (c) 2013, 2018, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -12682,10 +12682,7 @@ ha_innobase::discard_or_import_tablespace(
 		DBUG_RETURN(HA_ERR_TABLE_READONLY);
 	}
 
-	dict_table_t*	dict_table = m_prebuilt->table;
-
-	if (dict_table->is_temporary()) {
-
+	if (m_prebuilt->table->is_temporary()) {
 		ib_senderrf(
 			m_prebuilt->trx->mysql_thd, IB_LOG_LEVEL_ERROR,
 			ER_CANNOT_DISCARD_TEMPORARY_TABLE);
@@ -12693,11 +12690,11 @@ ha_innobase::discard_or_import_tablespace(
 		DBUG_RETURN(HA_ERR_TABLE_NEEDS_UPGRADE);
 	}
 
-	if (dict_table->space == fil_system.sys_space) {
+	if (m_prebuilt->table->space == fil_system.sys_space) {
 		ib_senderrf(
 			m_prebuilt->trx->mysql_thd, IB_LOG_LEVEL_ERROR,
 			ER_TABLE_IN_SYSTEM_TABLESPACE,
-			dict_table->name.m_name);
+			m_prebuilt->table->name.m_name);
 
 		DBUG_RETURN(HA_ERR_TABLE_NEEDS_UPGRADE);
 	}
@@ -12706,7 +12703,7 @@ ha_innobase::discard_or_import_tablespace(
 
 	/* Obtain an exclusive lock on the table. */
 	dberr_t	err = row_mysql_lock_table(
-		m_prebuilt->trx, dict_table, LOCK_X,
+		m_prebuilt->trx, m_prebuilt->table, LOCK_X,
 		discard ? "setting table lock for DISCARD TABLESPACE"
 			: "setting table lock for IMPORT TABLESPACE");
 
@@ -12719,32 +12716,32 @@ ha_innobase::discard_or_import_tablespace(
 		user may want to set the DISCARD flag in order to IMPORT
 		a new tablespace. */
 
-		if (!dict_table->is_readable()) {
+		if (!m_prebuilt->table->is_readable()) {
 			ib_senderrf(
 				m_prebuilt->trx->mysql_thd,
 				IB_LOG_LEVEL_WARN, ER_TABLESPACE_MISSING,
-				dict_table->name.m_name);
+				m_prebuilt->table->name.m_name);
 		}
 
 		err = row_discard_tablespace_for_mysql(
-			dict_table->name.m_name, m_prebuilt->trx);
+			m_prebuilt->table->name.m_name, m_prebuilt->trx);
 
-	} else if (dict_table->is_readable()) {
+	} else if (m_prebuilt->table->is_readable()) {
 		/* Commit the transaction in order to
 		release the table lock. */
 		trx_commit_for_mysql(m_prebuilt->trx);
 
 		ib::error() << "Unable to import tablespace "
-			<< dict_table->name << " because it already"
+			<< m_prebuilt->table->name << " because it already"
 			" exists.  Please DISCARD the tablespace"
 			" before IMPORT.";
 		ib_senderrf(
 			m_prebuilt->trx->mysql_thd, IB_LOG_LEVEL_ERROR,
-			ER_TABLESPACE_EXISTS, dict_table->name.m_name);
+			ER_TABLESPACE_EXISTS, m_prebuilt->table->name.m_name);
 
 		DBUG_RETURN(HA_ERR_TABLE_EXIST);
 	} else {
-		err = row_import_for_mysql(dict_table, m_prebuilt);
+		err = row_import_for_mysql(m_prebuilt->table, m_prebuilt);
 
 		if (err == DB_SUCCESS) {
 
@@ -12760,12 +12757,35 @@ ha_innobase::discard_or_import_tablespace(
 	/* Commit the transaction in order to release the table lock. */
 	trx_commit_for_mysql(m_prebuilt->trx);
 
-	if (err == DB_SUCCESS && !discard
-	    && dict_stats_is_persistent_enabled(dict_table)) {
+	if (discard || err != DB_SUCCESS) {
+		DBUG_RETURN(convert_error_code_to_mysql(
+				    err, m_prebuilt->table->flags, NULL));
+	}
+
+	/* Evict and reload the table definition in order to invoke
+	btr_cur_instant_init(). */
+	table_id_t id = m_prebuilt->table->id;
+	ut_ad(id);
+	mutex_enter(&dict_sys->mutex);
+	dict_table_close(m_prebuilt->table, TRUE, FALSE);
+	dict_table_remove_from_cache(m_prebuilt->table);
+	m_prebuilt->table = dict_table_open_on_id(id, TRUE,
+						  DICT_TABLE_OP_NORMAL);
+	mutex_exit(&dict_sys->mutex);
+	if (!m_prebuilt->table) {
+		err = DB_TABLE_NOT_FOUND;
+	} else {
+		if (const Field* ai = table->found_next_number_field) {
+			initialize_auto_increment(m_prebuilt->table, ai);
+		}
+		dict_stats_init(m_prebuilt->table);
+	}
+
+	if (dict_stats_is_persistent_enabled(m_prebuilt->table)) {
 		dberr_t		ret;
 
 		/* Adjust the persistent statistics. */
-		ret = dict_stats_update(dict_table,
+		ret = dict_stats_update(m_prebuilt->table,
 					DICT_STATS_RECALC_PERSISTENT);
 
 		if (ret != DB_SUCCESS) {
@@ -12775,11 +12795,12 @@ ha_innobase::discard_or_import_tablespace(
 				ER_ALTER_INFO,
 				"Error updating stats for table '%s'"
 				" after table rebuild: %s",
-				dict_table->name.m_name, ut_strerr(ret));
+				m_prebuilt->table->name.m_name,
+				ut_strerr(ret));
 		}
 	}
 
-	DBUG_RETURN(convert_error_code_to_mysql(err, dict_table->flags, NULL));
+	DBUG_RETURN(0);
 }
 
 /**

storage/innobase/row/row0import.cc

@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2012, 2016, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2015, 2018, MariaDB Corporation.
+Copyright (c) 2015, 2019, 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
@@ -1820,13 +1820,22 @@ PageConverter::update_index_page(
 
 	if (dict_index_is_clust(m_index->m_srv_index)) {
 		if (page_is_root(page)) {
+			dict_index_t* index = const_cast<dict_index_t*>(
+				m_index->m_srv_index);
 			/* Preserve the PAGE_ROOT_AUTO_INC. */
-			if (m_index->m_srv_index->table->supports_instant()
-			    && btr_cur_instant_root_init(
-				    const_cast<dict_index_t*>(
-					    m_index->m_srv_index),
-				    page)) {
-				return(DB_CORRUPTION);
+			if (index->table->supports_instant()) {
+				if (btr_cur_instant_root_init(index, page)) {
+					return(DB_CORRUPTION);
+				}
+
+				/* Provisionally set all instantly
+				added columns to be DEFAULT NULL. */
+				for (unsigned i = index->n_core_fields;
+				     i < index->n_fields; i++) {
+					dict_col_t* col = index->fields[i].col;
+					col->def_val.len = UNIV_SQL_NULL;
+					col->def_val.data = NULL;
+				}
 			}
 		} else {
 			/* Clear PAGE_MAX_TRX_ID so that it can be

storage/innobase/row/row0mysql.cc

@@ -3074,13 +3074,14 @@ row_discard_tablespace(
 	table->flags2 |= DICT_TF2_DISCARDED;
 	dict_table_change_id_in_cache(table, new_id);
 
-	/* Reset the root page numbers. */
+	dict_index_t* index = UT_LIST_GET_FIRST(table->indexes);
+	if (index) index->remove_instant();
 
-	for (dict_index_t* index = UT_LIST_GET_FIRST(table->indexes);
-	     index != 0;
-	     index = UT_LIST_GET_NEXT(indexes, index)) {
+	/* Reset the root page numbers. */
+	for (; index; index = UT_LIST_GET_NEXT(indexes, index)) {
 		index->page = FIL_NULL;
 	}
+
 	/* If the tablespace did not already exist or we couldn't
 	write to it, we treat that as a successful DISCARD. It is
 	unusable anyway. */